Phylogeny and biogeography of southern African spoon-winged lacewings (Neuroptera: Nemopteridae: Nemopterinae)

Phylogeny and biogeography of southern African spoon-winged lacewings (Neuroptera: Nemopteridae: Nemopterinae)
Phylogeny and biogeography of southern African spoon-winged lacewings
(Neuroptera: Nemopteridae: Nemopterinae)
Catherine L. Solea, Clarke H. Scholtza, Jonathan B. Balla and Mervyn W. Mansella
a
Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, Pretoria, South Africa
Corresponding author: Catherine L. Sole
Email: [email protected]
Telephone number: +27 12 420 3236
Fax: +27 12 3625242
Postal address: Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, Pretoria,
South Africa
Abstract
Nemopteridae are a charismatic family of lacewings characterised by uniquely extended hind wings.They
are an ancient widespread group in the drier regions of the world. The family comprises two subfamilies,
Crocinae (thread-wings) and Nemopterinae (spoon- and ribbon-wings). The present distribution of the
family has been largely influenced by the vicariant events of plate tectonics, resulting in relict populations
in some parts of the world and extensive evolutionary radiations in others, particularly southern Africa
where the vast majority of the species are endemic to the Western and Northern Cape Provinces of South
Africa. This study aimed to establish the validity of the 11 currently recognised genera and infer their
biogeographic history using molecular sequence data from four gene regions. The hypothesis that the
Cape nemopterines co-evolved with certain taxa in the Cape Floristic Region was also tested.
Phylogenetic analysis supports seven of the 11 currently recognised genera. The crown age of the
Nemopterinae is estimated to be at ca. 145.6 Mya, indicating that the group has been present since the
late Jurassic. Most of the genera appear to have diversified during the middle Eocene and into the middle
Miocene (ca. 44 - 11 Mya) with recent rapid radiation of several of the genera occurring during the late
Miocene (ca. 6 - 4.5 Mya). While these data support an initial radiation with the Rushioideae (Aizoaceae)
it is recommended that further study including observations and gut content be carried out. [238]
Keywords
Nemopteridae, Nemopterinae, Lacwings, Phylogeny, Biogeography, Cape Floristic Region
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1. Introduction
Nemopteridae are a charismatic family of lacewings characterised by uniquely extended hind wings.
They are the only entire insect family with this innovation that has further evolved into a range of striking
forms with specialised functions that include aerodynamics, camouflage, mate recognition and tactile
responses (Mansell, 1996). The family comprises two subfamilies, Crocinae (thread-wings) and
Nemopterinae (spoon- and ribbon-wings). Crocinae have filamentous hind wings that have a sensory
function in the confined cavernicolous habitats they occupy (Mansell, 1996), while those of
Nemopterinae vary from ribbon-shaped to extensive dilations that are pigmented and aerodynamically
twisted to provide stability during flight as well as camouflage when at rest (Mansell, 1996). In some
diurnal South African taxa additional functions of the hind wings include heat absorption when sitting on
a substrate and semiotic functioning when the black and white bilobed hind wings of Sicyoptera Navás
species are rapidly ratcheted dorsally and ventrally (Ball pers. obs.). Although these functions have been
refuted (Leon and Picker, 1990b; Picker, 1984) for the species Palmipenna aeoleoptera Picker, numerous
field observations (Ball, Brinkman and Mansell, pers. obs) on other taxa: Sicyoptera, Barbibucca Tjeder
and Palmipenna pilicornis Tjeder (1967) provide strong support for these functions. The ephemeral adults
usually have elongated mouthparts that have evolved in response to their specialist pollenophagous diet.
Larvae by contrast, are all predacious with the autapomorphy of piercing and sucking mouthparts that
defines the order Neuroptera. Larval nemopterids occupy a variety of habitats ranging from small caves
and rock overhangs, disused buildings and hollow tree trunks, to psammophiles and litter-dwellers, to
inquilines in the nests of ants. The first crocine larva, with a bizarrely elongated prothorax, was
discovered in tombs at the pyramids of Giza in Egypt (Roux, 1833), giving rise to the almostmythological status of Nemopteridae.
Nemopterids are an ancient group of lacewings that are widespread in the drier regions of the world,
with the exception of North America where the family is represented only by two fossil records
(Carpenter, 1959). Nemopteridae occur in parts of Africa, particularly southern Africa, Socotra Island (1
Nemopterinae, 1 Crocinae), Australia (3 Nemopterinae, 6 Crocinae), South America (1 Nemopterinae, 6
Crocinae), Mediterranean Europe, the Middle East and India (1 Crocinae). The southern African fauna
was originally monographed by Tjeder (1967), with several papers dealing with Crocinae (Mansell, 1976,
1977, 1980, 1981a, b, 1986, 1996) and the Nemopterinae (Leon and Picker, 1990a, b; Mansell, 1973;
Picker, 1984, 1987; Picker and Leon, 1990; Picker et al., 1991; Picker et al., 1992; Walker et al., 1994)
having followed Tjeder’s quintessential treatise.
There are currently 142 valid species worldwide, 43 Crocinae and 99 Nemopterinae, and at least a
further 10 undescribed nemopterine species in southern Africa. The present distribution of the family
appears to have been largely influenced by the vicariance events of plate tectonics, resulting in relic
populations in some parts of the world and extensive evolutionary radiations in others, particularly
2
southern Africa where 72 species, 48 % of the world’s Nemopteridae occur . The vast majority of these,
57 species (38% of the world fauna) are endemic to the Western and Northern Cape Provinces of South
Africa (Figure 1). The southern African Nemopterinae (excluding Crocinae) comprise 57% (62 species)
of the global fauna, with 47% of the world’s taxa (51 species) being endemic to these two provinces of
South Africa.
The Cape nemopterines are consequently a unique and rich biological heritage that requires special
research and conservation attention. While the subfamily Crocinae is comparatively well known,
knowledge of the taxonomy, biology, phylogeny, local biogeography and conservation status of the
Nemopterinae remains inadequate beyond that recorded by Tjeder (1967). While the conservation of
Crocinae is reasonably assured owing to their arid and rocky habitats, unsuited to agriculture, the
Nemopterinae are extremely vulnerable, as many of the habitats of the rare Cape endemics have already
been destroyed by agricultural and urban expansion, with the remainder being severely threatened.
The South African Nemopterinae are characterised by numerous fragmented populations, with
many species being known from a single locality only, and the almost clockwork precision of adult
emergence at specific times of the year and, sometimes only in certain years. This has engendered the
notion that they co-evolved with the species-rich Cape flora, leading to the hypothesis that certain plant
and nemopterine taxa may be interdependent (Mansell and Ball pers. obs.). Although the Crocinae are
central to the evolutionary processes of the family Nemopteridae, there are no observations to indicate
that their diversity in southern Africa has been influenced by flowering plant diversity to the same extent
as that of the Nemopterinae. The habitats of larval crocines are also different from those of nemopterines,
being confined to dusty recesses under rock overhangs, small caves and completely sheltered
microhabitats, whereas most nemopterines are not confined by precise habitat requirements, where many
species are psammophilous. This unrestricted habitat facilitates mass and synchronised emergence by
many nemopterine taxa (Mansell and Ball pers. obs.). The focus of this paper is consequently confined to
the subfamily Nemopterinae.
A detailed study of the taxonomy, with emphasis on molecular and morphological analysis,
phylogeny, phylogeography, biogeography and biology of the subfamily Nemopterinae is consequently
being undertaken. The first priority of these studies, and the main objective of this paper, was to establish
the validity of the currently recognised 11 genera using molecular data, as this would provide the basis for
investigations into their ecological role and objective criteria for the conservation of a unique South
African biological heritage. The overall project is especially designed to validate the hypothesis that the
Cape nemopterines co-evolved with certain taxa in the Cape flora, one of the world’s six floral kingdoms
(Galley and Linder, 2006; Goldblatt and Manning, 2002; Linder, 2003; Linder, 2005; Schulze et al.,
2005). By combining the data from four gene regions (16S rDNA, 18S, 28S domain 2 and COI) in a total
evidence approach we attempt to resolve the phylogenetic relationships of the 11 currently recognised
3
genera. In addition, we estimate divergence times for the origin and diversification of the major lineages
within the Nemopterinae.
.
2. Material and methods
2.1. In-group taxa
Ten of the eleven genera South African Nemopterinae were included in this phylogenetic study:
Barbibucca, Derhynchia Tjeder, Halterina Navás, Knersvlaktia Picker, Nemia Navás, Nemopterella
Banks, Nemeura Navás, Palmipenna Tjeder, Semirhynchia Tjeder and Sicyoptera. A single representative
of the Australian Nemopterinae, the genus Chasmoptera Westwood, was also included. The only genus
not included in this study is Nemopistha Navás, a rare Savanna biome taxon.
2.2. Out-group taxa
Considerations for out-group comparisons were based on a recent phylogenetic study of the Neuropterida
by Winterton et al. (2010). Based on this a species of Ascalaphidae (Neomelambrotus molestus Tjeder)
and a representative of the subfamily Crocinae (Laurhervasia setacea (Klug)) were used as out-group
taxa (See Table 1 for details of taxa used in this study).
2.3. Species identification
Morphological identifications were provided by a specialist on the group (M.W. Mansell) and based on
material in the South African National Collection of Insects, Pretoria and in the J.B. Ball Collection, Cape
Town. These two collections are the largest and most comprehensive holdings of southern African
Nemopteridae currently available. Molecular analyses were based on freshly-collected specimens,
authoritatively identified and further verified by comparison with material in these collections. Fresh
material was collected by hand-netting and at mercury vapour light traps and preserved in absolute
ethanol.
2.4. DNA extraction, cycling conditions and sequencing
Genomic DNA was extracted from a leg of at least three individuals per species representing each genus
using the Roche High Pure PCR Template Preparation Kit (Roche, Penzberg, Germany) according to the
manufacturer’s specifications.
Sequence data were generated for four different gene regions: three ribosomal genes (16S rDNA,
18S rDNA and a portion of the nuclear rRNA large subunit 28S domain 2), along with a single protein
coding gene region (cytochrome oxidase I - COI). Primer sequences used to amplify the four gene regions
are listed in Table 2. Amplification using polymerase chain reaction (PCR) was performed using the
4
following cycling conditions: a C. 456 base pair (bp) fragment of 16S rDNA was generated using the
primer pair LR-N-13398 (Simon et al., 1994) and LR-J-12961 (Cognato and Vogler, 2001) and 1221bp of
COI using the primer pair C1-J-1718 and TL2-N-3014 (Simon et al., 1994) with the following protocol:
initial denaturation at 95°C (5 min); 33 cycles of 93°C (20 s), 50°C (40 s), 72°C (20 s); final extension at
72°C (5 min). A C. 836bp of 18S rDNA was amplified using the primers 18S-intfw-ST12 and 18S-rev1
(Haring and Aspöck, 2004) with the following cycling conditions: initial denaturation at 95°C (2 min); 30
cycles of 95°C (10 s), 48°C (10 s), 72°C (1 min); final extension at 72°C (5 min). A ‘three-cycle’
touchdown PCR program was used to amplify C. 735bp stretch of 28S domain 2: initial denaturation for
20 seconds at 96°C was followed by 3 cycles (15 s at 96°C, 20 s at 54ºC, 1 min at 72°C), thereafter 7
cycles (12 s at 96°C, 18 s at 53°C, 55 seconds at 72°C) and 30 cycles (12 s at 96°C, 15 s 52°C, 50 s at
72°C) with a final extension of 1 minute at 72°C. For all gene regions PCR was performed in a final
volume of 50µl containing approximately 50 – 100 ng genomic DNA template, 2.5 mM MgCL2, 20 pmol
of each primer, 10 mm dNTP’s (0.25 mM of each of the four nucleotides (Promega)) and 1X buffer in the
presence of 1 unit of Taq DNA polymerase (Super-Therm® DNA polymerase, Southern Cross
Biotechnology)
2.5. Processing and alignment of sequences
All sequences were viewed, edited and assembled in CLC Bio 5.6 (http://www.clcbio.com/). Sequences
for 16S, 18S and 28S domain 2 were subsequently aligned using the algorithm described by Löytynoja
and Goldman (2005) as implemented in the Probabilistic Alignment Kit (PRANK:
http://www.ebi.ac.uk/goldMyan-srv/webPRANK) (Löytynoja and Goldman, 2005, 2008). Once aligned
these alignments were checked manually. Alignment results showed areas of these gene regions that are
conserved while others have significantly large amounts of inferred indels. Gblocks (Castresana, 2000)
was used to select confidently aligned areas by eliminating the poorly aligned positions and divergent
regions. The resulting alignment from Gblocks was used in subsequent analyses. The protein-coding gene
COI could unambiguously be aligned displaying no stop codons when translated in MacClade version
4.03 (Maddison and Maddison, 1992). Ambiguous sites were coded using the appropriate IUB symbols
after double-checking the electropherograms for recognisable sequencing artefacts. All sequences were
submitted to GenBank under accession numbers JX294077 – JX294294.
2.6. Phylogenetic analysis
Parsimony and Maximum Likelihood analyses were conducted using PAUP* 4.0b10 (Swofford, 2003).
We used a heuristic tree search protocol with 10 random addition sequences and tree bisection and
reconnection (TBR). For Parsimony we excluded all uninformative characters, gaps were treated as 5th
state characters and bootstrap support values (Felsenstein, 1985) were calculated based on 1000
5
replicates. Starting trees for the Maximum likelihood (ML) analysis were obtained through the NeighborJoining (NJ) method and bootstrap support values were calculated based on 100 replicates. For ML
inference a model for the entire dataset as favoured by the Akaike Information Criteria (AIC) was
estimated in MrModelTest version 2.2 (Nylander, 2004). Bayesian analyses were performed in MrBayes
version 3.1.2 (Huelsenbeck and Ronquist, 2001). All Bayesian analyses used the model favoured by the
AIC implemented in MrModelTest see Table 3 for models of the respective gene regions. All analyses
were initiated from random starting trees using one cold and three incrementally heated metropolis
coupled chains (0.01) run for 10 million iterations with trees being sampled every 1000 th iteration, of
which 20 % were discarded during the burn-in, with the posterior probabilities being calculated from the
remaining saved majority rule consensus trees. Two independently repeated Monte Carlo Markov Chain
(MCMC) approximation runs were performed.
2.7. Divergence time estimates
Relaxed molecular clock estimates of divergence time were estimated using Beast version 1.6.2
(Drummond and Rambaut, 2007), a Bayesian coalescent analysis with the MCMC approximation.
Nemopterinae were constrained to be monophyletic, reflecting our phylogenetic analysis, and the dataset
was partitioned by gene region, with the respective substitution models (Table 3) applied to each
partition. The fossil record for the Myrmeleontiforms is relatively diverse with the oldest fossils
appearing to represent the stem groups of the Nymphidae, Myrmeleontidae, Ascalaphidae, Psychopsidae
and Nemopteridae dating back to the Jurassic (Grimaldi and Engel, 2005). To reflect this a normal prior
was applied to the root using the mid-point of the Jurassic (172 million years ago (mya) with a standard
deviation of 11) to allow for soft minimum and maximum bounds of 144 and 200 mya, representing the
upper and lower bounds of the Jurassic epoch, respectively. Two fossils from the genus Marquettia,
morphologically considered the most primitive of the Nemopteridae, were described by Carpenter (1959),
from the Eocene-Oligocene boundary (33.9 mya) of the Florissant Shale in Colorado (Grimaldi and
Engel, 2005). Based on hind wing shape the fossil genus Marquettia appears morphologically similar to
the extant genus Sicyoptera we therefore used the midpoint of 34 million years (my) as a hard minimum
age constraint in an exponential prior for the node containing the genera Nemeura, Sicyoptera and
Semirhynchia. A soft maximum constraint was applied such that 97.5 % of the prior probability density
would fall prior to the 200 mya soft upper bound of the root of the tree. Priors on the ages of
unconstrained nodes were derived from a birth-death tree model. Two independent Markov chains were
run for 20 million iterations using a random starting tree. The program TRACER version 1.5 (Drummond
and Rambaut, 2007) was used to assess the convergence between runs and posterior probabilities of the
estimates.
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3. Results
3.1. Dataset properties and phylogeny
The combined aligned molecular matrix consisted of 2681 base pairs (bp): 16S ≈ 434 bp; 18S ≈ 798 bp;
domain 2 ≈ 663 bp and COI = 786 bp and included 1053 parsimony informative characters. As with most
arthropod genomes the A/T bias is reflected here across the four gene regions (Table 3). Parsimony
analysis recovered 957 trees with a length of 3431, CI of 0.505, RI of 0.853 and RC of 0.430. A single
ML tree was obtained assuming the GTR model with a gamma distribution shape parameter of 0.801 and
proportion of invariable sites 0.620. The phylogram depicted in Figure 2 is the Bayesian consensus tree
with Bayesian posterior probability, parsimony and ML bootstrap values presented on nodes. Only
values above 50% bootstrap and 0.5 posterior probability are indicated, and nodes with boostrap support
values above 70 % and/or posterior probability above 0.95 are considered as strongly supported nodes.
The Nemopterinae were strongly supported as being monophyletic (Bayesian posterior probability
(PP) 1.00, Parsimony bootstrap (PB) 98 % and Maximum Likelihood Bootstrap (MLB) 80 %). Two
distinct lineages can be identified within the phylogenetic trees labelled I (1.00 PP; 99 % PB; 97 % MLB)
and II (0.99 PP; 96 % PB; 76 % MLB) (Figure 2), respectively. There are currently 11 recognised genera
of Nemopterinae in southern Africa, based on morphological criteria. Within the phylogram seven of the
11 genera are well supported, based on their representative taxa: Barbibucca (1.00 PP; 86 % PB; 91 %
MLB), Derhynchia (1.0 PP; 100 % PB; 100 % MLB), Halterina (1.0 PP; 100 % PB; 100 % MLB),
Knersvlaktia (1.0 PP; 83 % PB; 99 % MLB), Nemopterella - excluding Nemopterella africana (1.0 PP;
100 % PB; 100 % MLB), Nemia (1.0 PP; 100 % PB; 100 % MLB) and Palmipenna (1.0 PP; 100 % PB;
99 % MLB). The genus Palmipenna appears sister to the genera Knersvlaktia, Nemopterella, Barbibuca,
Halterina, and Nemia (1.00 PP; 99 % PB; 97 % MLB). The genera Barbibucca and Nemia are well
supported as sister genera to each other (1.0 PP; 98 % PB; 99 % MLB) and are in turn sister to
Nemopterella Africana (1.0 PP; 83 % PB; 85 % MLB). A sister relationship between Halterina and
Knersvlaktia is only supported by the Bayesian analysis (0.97 PP). Lineage II contains the genera
Nemeura, Sicyoptera, Semirhynchia and Chasmoptera. Although this lineage is monophyletic and well
supported the genera Nemeura, Sicyoptera and Semirhynchia are polyphyletic. Derhynchia forms a wellsupported genus sister to all the genera in lineage II, including the Australian genus Chasmoptera.
3.2. Divergence estimates
The blue bars in Figure 3 indicate the 95 % high posterior density (HPD) interval for each divergence.
The mean estimated divergence of the Nemopterinae (including Chasmoptera) is ca. 145.61 million years
ago (mya), late Jurassic. The split between lineages I and II (as depicted in Figure 2) appears to have
occurred during the mid Cretaceous (ca. 119.71 mya). The divergence of the southern African
Nemopterinae appears to have occurred gradually with two distinct patterns being obvious. Most of the
7
genera appear to have diversified gradually during the middle Eocene (ca. 44 mya) to the middle Miocene
(ca. 11 mya) while other genera have diverged more recently during the last ca. 4.5 million years (Figure
3).
4. Discussion
This study is the most comprehensive phylogenetic analysis yet undertaken on Nemopterinae. The overall
phylogeny appeared well resolved, the Nemopterinae are monophyletic and a good indication is given as
to which genera are well supported.
4.1. Phylogenetic considerations
Two major lineages are revealed by the molecular analysis, the first comprising the genera Nemia,
Barbibucca, Halterina, Nemopterella, Knersvlaktia and Palmipenna (lineage I – Figure 2). The second
lineage consisting of Nemeura, Sicyoptera, Semirhynchia, and including the exotic Chasmoptera shows
two clear separations (Gen. & sp. nov, Semirhynchia sp. nov. and Chasmoptera) and a polyphyletic
complex of Nemeura, Sicyoptera cuspidata and Semirhynchia sp. nov., which requires further
investigation. The genera in lineages I and II are also distinguished morphologically in that the former
have abdomens that are short and stout, whereas the latter have long and slender abdomens. Pleuritocavae
occur sporadically in the male abdomen among the genera of lineage I, but are absent from all members
of lineage II. Nocturnally active species are divided between the two lineages, Nemopterella and Nemia
(lineage I) and Semirhynchia and Nemeura (lineage II). The remaining genera are diurnal a potential
further adaptation to their pollenophagous habits.
The close morphological similarity between Nemia and Nemopterella is not supported by molecular
data in the phylogeny (Figure 2). This raises the question of reliable morphological characters to
distinguish these two genera. Most Nemopterella species, which are morphologically difficult to separate
from one another, are superficially distinct from Nemia, although these morphological distinctions are
tenuous – requiring further study. Navás (1915) divided the genus Nemopterella into two, Nemeva, with
type species Nemopteryx africana Leach, 1815 and Nemia, with type species Nemoptera costalis
Westwood, 1836. According to Tjeder (1967) this separation was based on inconsistent characters of no
taxonomic significance, but he did discover an important feature, the presence of pleuritocavae in the
male of N. africana that were absent from that of N. costalis, and he separated the two genera on that
clear basis. Tjeder (1967) then synonymised Nemeva Navás with Nemopterella, as a valid existing name
(Nemopterella) cannot be substituted by a new name with the same type species. However, further
species recently discovered in South Africa that could be assigned to Nemia have pleuritocavae thereby
casting doubt upon their value in distinguishing Nemia and Nemopterella. Nemopterella africana is
indicated as distinct from both Nemia and Nemopterella although it shares the important distinguishing
features of both genera (pleuritocavae as in Nemopterella and the characteristic body patterns of Nemia).
8
It consequently suggests that N. africana may represent a previously undetected monotypic genus and
also that the main distinguishing feature currently separating Nemia and Nemopterella (pleuritocavae)
may not be supported by molecular data.
The genus Barbibucca is morphologically distinctive in that they are robust with uniformly broad hind
wings. The genus Knersvlaktia has been distinguished from other genera, and is clearly underpinned by
molecular data.The morphologically distinctive diurnal genus Palmipenna has several distinguishing
characters: antennae short and stout less than half forewing length, hind wings less than twice forewing
length with broad apical dilations and very small eyes characteristic of diurnal taxa. Molecular data
unequivocally support Palmipenna as a valid genus. The genus Halterina is also morphologically distinct,
and its two species are supported by molecular data.
Derhynchia is a distinct monotypic genus supported by the autapomorphy of reduced mouthparts and
rostrum, the only nemopterine with this unique feature. The biology of this genus is also unique in that it
inhabits the dunes in the Kalahari ecosystem where its free-living psammophilous larva lives several
centimetres under the sand surface near vegetation. The larva also has several unique features including
vestigial eyes and peculiar burrowing behaviour, indicating that the entire larval life is spent underground
(Mansell, 1973). The most readily available food source for adults is pollen from dune grasses that do not
require a long rostrum for harvesting, probably leading to the secondarily atrophied mouthparts.
In lineage II, Nemeura, Semirhynchia and Sicyoptera are morphologically distinct from one another.
Semirhynchia has distinctive short mouthparts and ribbon-shaped wings, while Sicyoptera is easily
distinguished from Nemeura by the broad double pre-apical expansions of the hind wings. The value of
the hind wing shape in distinguishing genera is however, questionable as broad hind wings occur over a
wide range of taxa, especially those in this study (lineages I and II). Furthermore, a newly discovered
taxon (Gen. & sp. nov.) which also has broad double pre-apical hind wing expansion, and closely
resembles species of Sicyoptera, separates out from other genera within this group, and is furthermore
distinguished by forewing characteristics supporting its molecular distinction
The molecular analysis applied in this study has led to three important conclusions. It has shown clear
support for at least seven of the southern African genera currently based on morphological criteria, it has
indicated that further studies, both morphological and molecular are required on the remaining three
genera, and it has also indicated the correct generic placement for taxa that were previously doubtful. It
has furthermore, revealed two distinct major lineages, with lineage II apparently more closely related to
the Australian Chasmoptera, possibly suggesting that it may comprise an ancestral lineage of the
Nemopterinae. The family is clearly a Gondwanan element with the sporadic relic distribution on the
southern continents being due to plate tectonics. Only one species, Stenorrhachus walkeri (McLachlan)
remains in South America, while one genus, Chasmoptera with three described species (C. hutti
(Westwood), C. mathewsi Koch and C. superba Tillyard all confined to Western Australia near Perth, is
the only representative of the Nemopterinae in the Australasian region. The fact that genera in lineage II
9
are most closely related to Chasmoptera suggests that they are part of the lineage that emerged before
South America and Australia became separated, and before the major radiation took place on the southern
African fragment. Chasmoptera is also morphologically very similar to Sicyoptera, and to the two fossil
Nemopterinae, Marquettia americana (Cockerell) and M. metzeli (Pierce and Kirkby), from North
America, as well as to some species of the Palaearctic genus, Lertha Navás, suggesting that the double
pre-apical dilation of the hind wing may be part of the “groundplan” of the Nemopterinae that has been
retained by widely disparate genera, including the enigmatic Parasicyoptera guichardi Tjeder, known
only from Socotra Island.
4.2. Biogeographic inferences and speciation events
The Cape Floristic Region (CFR), one of six floral kingdoms (Galley and Linder, 2006; Goldblatt and
Manning, 2002; Linder, 2003; Linder, 2005; Schulze et al., 2005) and its extent encompasses the bulk of
the distribution of the South African nemopterines (Figure 1). The biomes in which South African
Nemopterinae occur are Fynbos, Succulent Karoo, Nama Karoo, Albany Thicket and Savanna biomes
(Mucina and Rutherford, 2006). Recent detailed paleoclimatic records indicate that large fluctuations in
the African climate have caused changes, among others, in the topology, ecology and soil which, in turn,
has had a major effect on the speciation, extinction and dispersal of the flora and fauna over the last 5 - 6
mya (deMenocal, 2004). These landscape type changes result in the island-like fragmentation of a habitat,
which in turn may act as speciation ‘hotspots’ (Linder, 2003). One of the major driving forces behind the
floral diversification within CFR is thought to be the Plio-Pleistocene glacial and interglacial cycles and
the onset of the winter rainfall regime, having occurred ca. 5 mya (deMenocal, 1995; deMenocal, 2004;
Linder, 2003) with African bovids, birds and hominids having diversified over the last ca. 2 - 3 mya
(deMenocal, 2004; Linder, 2003; Potts, 1998). In particular, the increase in aridity that is accentuated by
the rain shadow created by the Great Escarpment and reinforced by the cold upwelling of the Benguela
current system and the subtropical anticyclone (Late Miocene) is thought to have played a major role in
the CFR diversification (deMenocal, 2004; Linder, 2003; van Zinderen Bakker, 1975; Ward et al., 1983).
It has been suggested that allopatric faunal distribution may have therefore been driven by distributional
changes and fragmentation of the flora as a result of climatic oscillations (Price et al., 2007; Tolley et al.,
2006).
The flora of the CFR sensu lato can be divided into three elements: (1) a Succulent Karoo element that
has its main diversity in the northern part of the CFR e.g. Mesembryanthemum sensu stricto (2) a Tropical
African element in which the main diversity occurs to the east of the CFR e.g. Rhus, Aloe and many
genera typical of ticket and forest vegetation and, (3) the so-called ‘Cape clades’ occurring in the South
Western Region (Bolus, 1886) that all have their species richness centred within the CFR e.g. Erica,
Proteaceae, Bruniaceae, Restionaceae p.p, and Phylica.
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It is hypothesised here that the Nemopterinae have co-evolved mainly with Ruschioideae (Aizoaceae).
The Aizoaceae have their greatest diversity in the summer-dry west and reach into Namaqualand up to the
Orange River (Linder, 2003). The sub-family Ruschioideae contains approximately1600 species almost
exclusively endemic to southern Africa, are the most speciose sub-family within the Aizoaceae and
dominate the Namaqualand in terms of species numbers and density. The core Ruschiodeae radiation
driven by the onset of the winter rainfall regime was estimated to have occurred c. 3.8 - 7.8 Ma (Klak et
al., 2004).
Two hypotheses exist regarding the high species diversity of the CFR, either the flora and fauna of the
CFR have undergone rapid diversification or there has been a slow accumulation of species over time
(Galley et al., 2007; Linder, 2003). When looking more closely at the climatic changes since the early
Oligocene, the west appears to have undergone a gradual change in climate (Linder, 2005), arid to semiarid conditions interspersed with wetter periods (Klak et al., 2004), indicating that the two hypotheses are
not necessarily mutually exclusive. A wide range of postulated dates exists for the radiation of the Cape
Flora, those dating back to the arid phase in the early Oligocene indicate a slow accumulation of
diversity, while others show typical recent rapid radiations (Linder, 2005). The crown age of the
Nemopterinae is estimated to be at ca. 119.7 mya (144.8 – 97.2; upper and lower estimates, respectively),
indicating that the group has been present since the Cretaceous. Most of the genera appear to have
diversified during the middle Eocene and into the middle Miocene (ca. 44 - 11 mya, Figure 3) with recent
rapid divergence of several of the genera, Barbibucca, Nemia, Nemopterella, Nemeura, Palmipenna and
Sicyoptera/Semirhynchia, occurring during the late Miocene (ca. 4.5 mya), alluding to the fact that the
diversification of the Nemopterinae appears to support both these hypotheses. The timing of the recent
diversification events seems to follow the recent speciation of the Ruschioideae, indicating that an
adaptive shift of the nemopterines may have occurred in response to the Ruschioideae distribution shifts
linked to climatic oscillations. Further empirical evidence however is needed to test whether this is an
adaptive radiation. Present observations, noted on radially symmetrical flowers, of adult nemopterine
pollen feeding include the plant families Aizoaceae, Asteraceae and Molluginaceae (Ball pers. obs.).
Feeding behaviour of Nemoptera sinuata Olivier in the Balkan-Anatolian peninsular was noted on
flowers from the families Asteraceae and Brassicaceae (Krenn et al., 2008). It is therefore possible that
the initial diversification of Nemopterinae was influenced by the radiation of the ruschoids, and that they
subsequently adapted to feeding on other plant species as well. This is a hypothesis that will be tested in
subsequent studies on pollen composition in the alimentary canals of preserved and freshly-collected
specimens, as well as field observations. The greatest extant concentration of nemopterines is in the more
arid portions of the Western and Northern Cape Provinces, where a variety of families of ephemeral
spring flowers are visited by a large number of different orders of insects. Present local observations (Ball
pers. obs.) confirm that the community patterns of plant-pollinator interactions reveal that angiosperm
11
species are typically visited by many taxa of potential pollinators and that the majority of flower visitors
are noted on multiple plant species (Geber and Moeller, 2006; Waser and Ollerton, 2006).
Apart from the radiation in South Africa, there has also been a similar, albeit smaller, radiation of a
single genus, Chasmoptera in Western Australia where three species occur. In the southern Palaearctic
there has been a radiation of two genera, Nemoptera Latrielle and Lertha. Both of these areas share a
Mediterranean climate similar to that of the Western Cape Province of South Africa. The South African
genus, Sicyoptera, most closely resembles Chasmoptera and Lertha and is restricted to the fynbos
component in the south western part of the Western Cape Province, whereas most of the recent radiation
of genera has taken place along the central and northern parts of the west coast area, where the largest
simultaneous radiation of Ruschioideae has also taken place (Klak et al., 2004).
Acknowledgements
The authors would like to thank Tony Brinkman and Andre Marais for their patience, time and passion in
collecting samples of this enigmatic group without which this study would not have been possible. CS is
indebted to Isa-Rita Russo for all her hard work in the lab. Christian Deschodt is thanked for his help with
drawing the map. Funding for the genetic analysis was provided through the National Research
Foundation (NRF) with additional private funding from J.B. Ball.
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17
Figure 1. Map indicating the genera and species localities of the Nemopterinae.
18
Figure 2. Bayesian phylogram of combined dataset analysis (COI, 16S, 18S and 28S domain 2). Posterior probabilities, parsimony and ML bootstrap are
given, respectively. Dashes (-) on nodes indicate weak/no support.
19
Figure 3. Estimated times of divergence for the major lineages of the Nemopterinae. Nodes on the phylogram represent means of the probability
distributions for node ages. The time intervals for the 95 % probability of actual age are represented as blue bars. Green box represents the time period of
slow accumulation of genera, blue box represents recent diversification.
20
Table 1. Sampled species for this study along with their collection locality. X – indicates amplification failed i.e. no sequence data available, Comb. –
indicates the samples used in the combined analysis
Taxon
Locality
Specimen ID
COI
16S
28S domain 2
18S
Comb.
Barbibucca biremis
Graafwater
BBGW01
√
√
√
√
√
Barbibucca elegans
Klompbome, Loeriesfontein
BEL01
√
√
X
X
√
Klompbome, Loeriesfontein
BEL02
√
√
√
√
√
Barbibucca sp.
Wallekraal
BWK01
√
√
√
√
√
Barbibucca sp.
Knersvlakte
BKP01
X
√
√
√
√
Chasmoptera huitti
Coorow, Western Australia
CS01
√
√
√
√
√
Derhynchia vansoni
Tswalu - Gosa Dunes
DVT01
√
√
√
√
√
Tswalu - Gosa Dunes
DVT02
√
√
√
√
√
Tswalu - Gosa Dunes
DVT03
√
√
√
√
√
Halterina sp. nov.
Zandrug 10km north Clanwilliam
HBCZ03
√
√
√
√
√
Halterina pulchella
Koeberg
HPCT01
√
√
√
√
√
Knersvlaktia nigroptera
Knersvlakte
KNK01
√
√
√
√
√
Knersvlakte
KNK02
√
√
√
X
√
Knersvlaktia sp. nov.
Vyftienmylberg
BVB01
√
√
X
√
√
Nemia costalis
Clanwilliam
NCCD02
√
√
√
√
√
Clanwilliam
NCCD03
√
√
√
√
√
Clanwilliam
NCCD04
√
√
√
√
√
Marydale, Swartkopspan
NAMD01
√
√
√
√
√
Marydale, Swartkopspan
NAMD02
√
√
√
√
√
Nemia karrooa
21
Taxon
Locality
Specimen ID
COI
16S
28S domain 2
18S
Comb.
Nemopterella africana
Doornfontein
NKDTK01
√
√
√
√
√
Doornfontein
NKDTK03
√
√
X
√
√
Doornfontein
NKDTK04
√
√
√
√
√
Uitkyk, Piketberg
NAC02
√
√
√
√
√
Uitkyk, Piketberg
NAC03
√
√
√
√
√
Sterkfontein
NLTS01
√
√
√
√
√
Sterkfontein
NLTS02
√
√
√
√
√
Vioolsdrif
NMSK01
√
√
√
√
√
Vioolsdrif
NMSK02
√
√
√
√
√
Vioolsdrif
NMSK03
√
√
√
√
√
Vioolsdrif
NPSK01
√
√
√
√
√
Vioolsdrif
NPSK03
√
√
√
√
√
Vioolsdrif
NPSK05
√
√
X
√
√
Nemopterella papio
Vioolsdrif
NPVD01
√
√
√
√
√
Nemopterella peringueyi
Beaufort West
NBW01
√
√
√
√
√
Nemopterella sp.
Tswalu Reserve
NSS01
√
√
√
√
√
Tswalu Reserve
NSS02
√
√
√
√
√
Worcester
NGW01
√
√
√
√
√
Worcester
NGW02
√
√
√
√
√
Worcester
NGW03
√
√
√
√
√
Biedou' Clanwilliam
PAC02
√
√
√
√
√
Biedou' Clanwilliam
PAC03
√
√
√
√
√
Biedou' Clanwilliam
PAC10
√
√
√
√
√
Nemopterella longicornis
Nemopterella munroi
Nemopterella papio
Nemeura gracilis
Palmipenna aeoleoptera
22
Taxon
Locality
Specimen ID
COI
16S
28S domain 2
18S
Comb.
Palmipenna palmulata
Brandkop
PBK01
√
√
√
√
√
Kobee Pass
PPKP02
√
√
X
√
√
Biedou' Clanwilliam
PPB02
√
√
X
√
√
Biedou' Clanwilliam
PPB03
√
√
X
√
√
Semirhynchia sp. nov.
Clanwilliam
SMC02
√
√
X
√
√
Semirhynchia sp. nov.
Vanrhynsdorp - Kobee Pass
SV01
√
√
√
√
√
Sicyoptera cuspidata
Worcester
SCBB01
√
√
√
√
√
Sicyoptera dilatata
Galgeberg
SDGG01
√
√
X
√
√
Galgeberg
SDGG02
√
√
√
√
√
Galgeberg
SDGG03
X
√
√
√
√
Galgeberg
SDGB01
√
√
√
√
√
Welbedacht
SWB01
√
√
√
X
√
SWB02
√
√
√
X
√
Kamieskroon
SSKK01
√
√
√
√
√
Ascalaphidae (Neomelambrotus molestus)
Klipvlei Farm
MA01
√
√
√
√
√
Crocinae (Laurhervasia setacea)
Kelkiewyn Farm
LSKF01
√
√
√
X
√
Crocinae (Laurhervasia setacea)
Piketberg ‘Uitkyk’
CPC01
√
√
√
X
√
Palmipenna pilicornis
Sicyoptera sp. nov.
Gen. & sp. nov.
Out-groups
23
Table 2. Summary of oligonucleotide primers used in this study
Locus (length)
Primer name and sequence
Length
Reference
Cytochrome oxidase I
C1-J-2183 (5’CAACATTTATTTTGATTTTTTGG 3’)
23mer
Simon et al., (1994)
TL2-N-3014 (TCCAATGCACTAATCTGCCATATTA 3’)
25mer
Simon et al., (1994)
LR-J-12961 (5' TTTAATCCAACATCGAGG 3')
18mer
Cognato and Vogler (2001)
LRN-N-13398 (5' CGCCTGTTTAACAAAAACAT 3')
20mer
Simon et al., (1994)
D2-3551 (5’ CGTGTTGCTTGATAGTGCAGC 3’)
21mer
Gillespie [et al., (2005)
D2-4057 (5’ TCAAGACGGGTCCTGAAAGT 3’)
20mer
Gillespie et al., (2005)
18S-intfw-STI2 (5' ATCAAGAACGAAAGTTAGAG 3')
20mer
Haring and Aspöck (2004)
18S-rev1 (5' ATGGGGAACAATTGCAAGC 3')
19mer
Haring and Aspöck (2004)
16S rRNA
28S rRNA domain 2
18S rRNA
Table 3. Data characteristics and estimated model parameters for 16S, COI, 28S domain 2 and 18S datasets as applied to the MrBayes and *BEAST
analyses (I = proportion of invariable sites).
16S
COI
D2
18S
Best-fit model
GTR + I + G
HKY + I + G
GTR + I + G
GTR + I + G
A frequency
0.405
0.374
0.336
0.255
C frequency
0.154
0.152
0.123
0.199
G frequency
0.084
0.068
0.167
0.242
T frequency
0.358
0.406
0.373
0.305
Gamma
1.529
0.381
0.675
0.454
I
0.579
0.467
0.
0.581
24
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