Taxonomy of the ant genus Nesomyrmex Wheeler (Formicidae, Myrmicinae) in the Afrotropical region, with a review of current species groups and description of a new species of the N. angulatus group from Mozambique

This study reviews the taxonomy of the ant genus Nesomyrmex Wheeler, 1910 in the Afrotropical region. Previous revisionary studies are discussed and four species groups are proposed on the basis of external morphology. The N. angulatus group contains seven species that are widely distributed throughout the whole Afrotropical region, with one species also occurring in the Palaearctic and Malagasy regions. The N. cataulacoides group is monotypic, with one morphologically bizarre species found in Equatorial rain forests. The N. humerosus group is also monotypic and occurs in East Africa. The last and by far most species-rich group is the N. simoni group that contains 17 species, all of which are endemic to South Africa. The four groups are defined for the first time for the region, and an illustrated identification key is provided. Furthermore, the N. angulatus group is more thoroughly reviewed. One new species from Mozambique is described, N. inhaca sp. nov., and species accounts for the other six are provided. Also, an illustrated identification key to the species of the N. angulatus group is presented.


Introduction
Nesomyrmex Wheeler, 1910 is a moderately-sized genus of myrmicine ants distributed in the tropics and subtropics of the Neotropical, Afrotropical and Malagasy regions (Guénard & Economo 2016).It was traditionally grouped within the tribes Leptothoracini or Formicoxenini, but the most recent phylogeny of the Myrmicinae revealed it to be a member of the Crematogastrini (Ward et al. 2015).At present, Nesomyrmex contains 55 valid species (Bolton 2016), of which 21 are Neotropical, 25 Afrotropical, and nine Malagasy (Kempf 1959;Brandão 1991;Bolton 2003;Mbanyana & Robertson 2008;Csősz & Fisher 2015).Two extinct species are known from Dominican Amber (De Andrade et al. 1999).For most of its existence Nesomyrmex was treated by most authorities as either a subgenus or junior synonym of the much more diverse and widespread genus Leptothorax Mayr, 1855(e.g., Wheeler 1922;Kempf 1959;Bolton 1982).Relatively recently, Bolton (2003) revived it from synonymy with Leptothorax and raised it to full genus status by providing a thorough generic diagnosis and distinguishing it from other closely related genera.The most recent multi-locus molecular phylogeny of the subfamily Myrmicinae strongly supports the monophyly of the genus (Ward et al. 2015).The alpha taxonomy of the genus in the Afrotropical region is in reasonably good condition.Bolton (1982) revised the genus (as part of Leptothorax), recognised nine species, and gave a species level key to the then known species.Later, Snelling (1992) described the morphologically bizarre N. cataulacoides from Cameroon as a tenth Afrotropical species.More recently, Mbanyana & Robertson (2008) provided an extensive revision of the Nesomyrmex of southern Africa.They recognised 20 species from South Africa, of which they described 15 as new, leading to a total of 25 Nesomyrmex species for the whole Afrotropical region.
During a recent taxonomic survey of the Tetramorium Mayr, 1855 fauna of Mozambique hosted in the ant collection of the Museum of Comparative Zoology, Harvard University Cambridge, the first author encountered a strange looking series from Inhaca Island.After a closer look it became apparent that this series was accidentally mislabelled as Tetramorium, but clearly belonged to the genus Nesomyrmex.While the genus identity was easily assessed, it was impossible to identify the species on the basis of the currently available taxonomic identification keys (Bolton 1982;Mbanyana & Robertson 2008).A more thorough examination and comparison with reference material revealed that the material belonged to a new, undescribed species.In this study we review the Nesomyrmex species groups found in the Afrotropical region and provide an identification key to the four proposed groups herein: N. angulatus group, N. cataulacoides group, N. humerosus group and N. simoni group.In addition, we review the N. angulatus group and describe the new species as N. inhaca sp.nov.In order to aid in identification we also provide an illustrated key to all species of the N. angulatus group.

Abbreviations of depositories
The collection abbreviations given below follow Evenhuis (2016).The material upon which this study is based on is located and/or was examined at the following institutions: BMNH = The Natural History Museum, London, U.K. HLMD = State Museum of Hesse Darmstadt, Darmstadt, Germany MCZC = Museum of Comparative Zoology, Harvard University, Cambridge, U.S.A. KSMA = Museum of Arthropods, King Saud University, Riyadh, Kingdom of Saudi Arabia SAMC = Iziko Museum of Cape Town, Cape Town, South Africa ZFMK = Zoological Research Museum Alexander Koenig, Bonn, Germany

Class
The following newly developed identification key to species groups is loosely based on Bolton (1982) and Mbanyana & Robertson (2008), and also incorporates ideas from Snelling (1992).

Nesomyrmex angulatus species group Definition
Antennae with 12 segments; anterior clypeal lobe conspicuously convex, rounded and without a small median triangular projection; frontal carinae absent; propodeum always with moderately long to long spines, in profile distinctly longer than their basal width; petiole and postpetiole without large lateral spines, petiole sometimes with small denticles; all dorsal surfaces of body with short, blunt pilosity (with the exception of N. evelynae, which lacks standing hairs on most of first gastral tergite).

Comments
This group contains seven species that are widely distributed in the Afrotropical region, with one species extending into the Palaearctic and Malagasy regions.All species appear to be arboreal or subarboreal.Species accounts for all group members are provided below in the review of the group.The alpha taxonomy of the group appears straightforward based on the literature (Bolton 1982;Mbanyana & Robertson 2008).However, we find some species delimitations quite problematic (see species accounts below) and it might be necessary to revise the N. angulatus species group in the future after the accumulation of more material from additional Afrotropical localities.

Nesomyrmex cataulacoides species group Definition
Antennae with 11 segments; anterior clypeal lobe conspicuously convex and rounded, without a small median triangular projection; frontal carinae absent; propodeal spines very well developed, long and spiniform; petiole and postpetiole each with a pair of large and conspicuous lateral spines; all dorsal surfaces of body without standing pilosity.

Comments
The N. cataulacoides species group holds only one morphologically bizarre and extraordinary species, which is impossible to confuse with any other Nesomyrmex species from the Afrotropical or any other region.The 11-segmented antennae, lack of standing pilosity on all dorsal surfaces, and the extreme spinosity render N. cataulacoides immediately recognizable.The possession of spines/teeth on the anterior pronotal corners, the anterior and posterior propodeum, and on both waist segments is unique within the genus.The affinities of N. cataulacoides to other Nesomyrmex are difficult to ascertain, mostly due to the extreme morphological specializations.So far it is not possible to associate it closely with any other Nesomyrmex species or species group.Currently, the species is known only from Cameroon and Kenya.Based on the few collections available, this species is strictly arboreal.The observed disjunctive distribution is most likely a sampling artefact due to the scarcity of collecting in Central African canopies, and we expect that N. cataulacoides will be collected in intermediate countries in the future.

Nesomyrmex humerosus species group Definition
Antennae with 12 segments; anterior clypeal lobe short, flat-margined, and never convex, with small median triangular projection; frontal carinae present, but weakly developed; propodeal spines very well developed, long and spiniform; petiole and postpetiole without lateral spines; all dorsal surfaces of body with short, blunt pilosity.

Comments
This group contains only one species, which is morphologically quite unique in the Afrotropical region.Of special importance are the short, flat-margined anterior clypeal lobe with a small median triangular projection and the barrel-shaped petiolar node with its small, triangular node.These characters are in slightly modified ways also seen in several Neotropical and Malagasy species, while they are absent in the other Afrotropical species groups.However, the fact that N. humerosus shares these characters with species from other regions does not necessarily mean that N. humerosus is more closely related to them.It could also be an independent African lineage and similarities with species from other regions might be based on convergence.Despite the fact that N. humerosus does not resemble most species from the N. simoni group, it still shares characters with some species, such as the large eyes and the shape of the dorsal mesosomal outline, and it could be that N. humerosus is just an aberrant N. simoni group member.At present, it is not possible to deduce the biogeographical and phylogenetic affinities of this peculiar species.Currently, N. humerosus is known to occur in Kenya, Tanzania and Yemen.It is a rather rarely collected species and our scarce knowledge is based on just four collection events.Based on a sample collected in Kenya by the first author, it seems to live on vegetation, but it was also sampled from the ground in Tanzania and Yemen.It is possible that the species also occurs in other East African countries, such as Somalia and Mozambique, which are greatly under-sampled.

Nesomyrmex simoni species group Definition
Antennae with 12 segments; anterior clypeal lobe conspicuously convex and rounded, without a small median triangular projection; frontal carinae absent; propodeum usually unarmed, rarely with short teeth, in profile no longer than their basal width; petiole and postpetiole without lateral spines; usually all dorsal surfaces of body with (mostly) long, fine or (rarely) short, blunt standing pilosity, sometimes pilosity reduced on a few body parts, but never completely absent from all dorsal surfaces.

Comments
The 17 species of this group are all endemic to South Africa.In contrast to the members of most other Afrotropical groups, all N. simoni group species nest and live on the ground.Mbanyana & Robertson (2008) revised this group extensively, provided a sound and functional species identification key, and presented detailed descriptions of all species.Consequently, in this study we do not go into further details concerning the N. simoni group and refer to Mbanyana & Robertson (2008).

Diagnosis
The following character combination distinguishes N. angulatus from the other members of the group: in profile mesosomal dorsum forming a single, uninterrupted flat surface without any trace of metanotal groove; petiolar peduncle short; body colour yellow to very light brown.

Diagnostic comments
Nesomyrmex angulatus together with N. grisoni are easily separable from the other members of the group on the basis of the dorsal mesosomal outline, which is an uninterrupted, flat surface without any trace of a metanotal groove.The separation of N. angulatus from N. grisoni is less clear though.As Bolton (1982) stated in his revision, the only differentiating character is body colour, which is yellowish in N. angulatus and dark brown to black in N. grisoni.In general, body coloration is a rather weak diagnostic character and extremely variable in many ant species, and it is likely that both species are actually conspecific and the differently coloured forms represent geographic or ecological variants.The latter seems probable if one considers that N. angulatus is predominantly an arid-adapted species, while N. grisoni appears to prefer humid rain forests.Nevertheless, at the moment we hesitate to synonymise the two species and prefer to keep them separate for the following reasons.First, while there is a lot of material of N. angulatus in many museums, there is not much of N. grisoni, making comparative analyses challenging.Secondly, and more importantly, we are not fully convinced that all the material currently listed and identified as N. angulatus represents the same species.On the basis of some recent collections from Kenya and Mozambique we were able to observe a lot of morphological variation within and between localities.As already noted by Bolton (1982), the shape of the petiolar node seems to be especially variable.Consequently, we cannot rule out the possibility of dealing with a complex of more or less cryptic species.At the same time it is possible that N. angulatus is not only a very successful and widespread, but also an extremely variable species.The solution to this problem is not the aim of this study, since it requires the accumulation of an extensive amount of material from all over Africa, the Arabian Peninsula, and the Malagasy region.

Biology
Nesomyrmex angulatus was collected from a variety of habitat types, such as tropical dry forest, coastal scrub, mangrove forest, savannah, and Acacia woodland.In general it seems as if the species prefers comparatively arid environments.In addition, it is predominantly found on the trunk of trees or the lower vegetation, rarely on the ground, and it nests in pre-existing cavities of dead wood (Bolton 1982;Mbanyana & Robertson 2008).

Distribution
This species has by far the widest distribution range within the N. angulatus group, and likely represents the most widespread Nesomyrmex species on a global scale.It is found in the majority of African countries, as well as on the Arabian Peninsula and in most of the Malagasy region.

Diagnosis
The following character combination separates N. denticulatus from the remainder of the group: eyes with 10-12 ommatidia in longest row; in profile mesosomal dorsum with conspicuously impressed metanotal groove; in dorsal view petiolar node laterally denticulate; subpetiolar process with a conspicuous tooth anteriorly followed by a long cuticular flange which runs back to the postpetiolar junction; dorsum of propodeum with standing hairs; first gastral tergite with standing hairs evenly distributed throughout.

Diagnostic comments
The three species, N. denticulatus, N. innocens and N. stramineus, are morphologically very similar and can be well separated from the other species by the laterally denticulate petiolar node.The separation of these three can be challenging though.Nesomyrmex denticulatus is larger in general body size, has larger eyes with more ommatidia, and a subpetiolar process with a conspicuous tooth anteriorly, followed by a long cuticular flange which runs back to the postpetiolar junction, and slightly denser pilosity.

Biology
This species usually nests in cavities of branches on trees and bushes previously excavated by woodboring beetles, lepidopteran larvae or termites (Mbanyana & Robertson 2008).It is found in a variety of more arid habitats, such as late succession Fynbos, Succulent Karoo with large bushes, along edges of Southern Afrotemperate Forest, and possibly also Albany Thicket (Mbanyana & Robertson 2008).

Distribution
Nesomyrmex denticulatus is only known from South Africa, where it seems to be relatively common in the Western and Eastern Cape regions.

Diagnosis
The following character combination distinguishes N. evelynae from the other species of the group: in profile mesosomal dorsum with conspicuously impressed metanotal groove; petiolar peduncle long; dorsum of propodeum without standing hairs; first gastral tergite lacking standing hairs except for single transverse row on posterior end of tergite.

Diagnostic comments
The recognition of this species within the N. angulatus group is fairly straightforward, since it is the only one that lacks standing hairs on most of the first gastral tergite while all other group species have standing hairs evenly distributed throughout this tergite.It also lacks standing hairs on the propodeum, a character shared only with N. inhaca sp.nov., whereas the other five species have short, standing pilosity on the propodeum.

Biology
It prefers rain forests where it lives in the canopy stratum.Based on canopy fogging samples from Kenya available to the first author, it appears that this species is found commonly on trees, even though in small individual numbers, suggesting smaller colony sizes.

Distribution
Nesomyrmex evelynae is found in Equatorial Africa ranging from Burkina Faso and Ghana in the west through the Central African Republic and the D.R. Congo to Uganda and Kenya in the east.The known distribution is disjunctive since N. evelynae is not known from the countries between Ghana and the Central African Republic and the D.R. Congo.We consider this more of a sampling artefact though, and expect the species to be collected from the countries in between in future sampling projects.

Diagnosis
The following character combination distinguishes N. grisoni from the other species of the group: in profile mesosomal dorsum forming a single, uninterrupted flat surface without any trace of metanotal groove; petiolar peduncle short; body colour dark brown to black.

Diagnostic comments
As mentioned above, N. grisoni and N. angulatus are straightforwardly distinguishable from the remainder of the group.At the same time they are morphologically very close to each other and only separable on the basis of body colour.For a more in-depth discussion we refer to the species account of N. angulatus.

Biology
Very little information about the natural history of this species is available.It seems to live on vegetation in rain forest habitats.

Distribution
Nesomyrmex grisoni is only known from the Central African Republic, the D.R. Congo and Ghana.

Diagnosis
The following character combination distinguishes N. inhaca sp.nov.from the other members of the N. angulatus group: in profile mesosomal dorsum with conspicuously impressed metanotal groove; in dorsal view petiolar node not laterally denticulate; dorsum of propodeum without standing hairs; first gastral tergite with standing hairs evenly distributed throughout.

Etymology
The new species is named after the type locality, Inhaca Island, to the southeast of Mozambique.The species epithet is a noun in apposition and thus invariant.
Waist segMents and gaster.Petiolar peduncle long, anteriorly with a small tooth-like subpetiolar process; in profile petiolar node relatively low and globular, between 1.4 and 1.5 times as high as long (LPeI 64-70); anterior face smoothly merging with peduncle and petiolar dorsum without any angles, posterior face slightly better developed; node in dorsal view about 1.3 to 1.4 times as wide as long (DPeI 127-141); in dorsal view petiolar node not laterally denticulate; in profile postpetiole globular, about 1.1 to 1.2 times as high as long (LPpI 86-93); in dorsal view about 1.4 and 1.5 times as wide as long (DPpI 140-147); postpetiole in dorsal view around 1.4 to 1.5 times as wide as petiolar node .
pilosity and pubescence.Head, mesosoma, waist segments and gaster dorsally with sparse, erect, blunt, and moderately long pilosity, hairs shorter on head and mesosoma than on waist segments and gaster; head laterally and ventrally with short appressed to decumbent pubescence; pubescence on mesosoma and waist segments sparse to absent; first gastral tergite with short to moderately long, appressed to decumbent pubescence.coloration.Body uniformly yellowish to light brown, in a few specimens legs slightly lighter yellow, almost white.

Diagnostic comments
Within the members of the N. angulatus species group, N. inhaca sp.nov.cannot be mistaken for N. evelynae since the latter is devoid of standing hairs on the first gastral tergite except for a single transverse row on the posterior end of the tergite, and also has very long propodeal spines and a relatively high petiolar node.Nesomyrmex inhaca sp.nov.has short, standing hairs evenly distributed throughout the first gastral tergite, shorter propodeal spines and a much lower petiolar node.The species pair N. angulatus and N. grisoni both do not possess a trace of a metanotal groove, which is obviously present in N. inhaca sp.nov.and thus it is not likely these species will be confused.Nevertheless, N. inhaca sp.nov. is morphologically closer to the trio of species N. denticulatus, N. innocens and N. stramineus.These European Journal of Taxonomy 258: 1-31 (2017) three are, however, easily separable since they possess a petiolar node with distinct lateral denticles and have standing hairs on the propodeal dorsum, while N. inhaca sp.nov.lacks both the lateral petiolar denticles and the standing hairs on the propodeum.Moreover, N. inhaca sp.nov.has apparently longer antennal scapes based on the much higher SI (94-95) compared to the other three species .This is partly due to the fact that N. inhaca sp.nov.has indeed relatively longer antennal scapes, but the comparatively narrow head with low values of HW contributes to these high SI values.Therefore, we suggest being cautious with scape length as the single diagnostic character.

Intraspecific variation
Since the description is based on just one collection event, the observed intraspecific variation seen in the worker caste is very low.However, the sculpture on the first gastral tergite shows some variability, as described above.

Biology
Nesomyrmex inhaca sp.nov.was sampled from low vegetation in secondary forest at an elevation of 1 m.Apart from this, nothing is known of its natural history.

Distribution
The new species is so far only known from one collection event on Inhaca Island in the southeast of Mozambique.Despite this apparently restricted distribution to just one island, we are reluctant to declare N. inhaca sp.nov.as endemic to Inhaca Island.With the noticeable exception of the area around Gorongosa, most of Mozambique remains severely under-sampled and our knowledge of local ant communities and species distributions is very poor to non-existent.Consequently, it is possible that N. inhaca sp.nov.will also be found on the mainland.(Forel, 1913) Figs 12B, 13A, 19

Diagnosis
The following character combination distinguishes N. innocens from the other members of the group: eyes with 7-9 ommatidia in longest row; in profile mesosomal dorsum with conspicuously impressed metanotal groove; propodeal spines short and thick, elongate-triangular and only weakly longer than their basal width; in profile petiolar node nodiform, appearing approximately as long as high; in dorsal view petiolar node laterally denticulate; subpetiolar process without a long cuticular flange running back to the postpetiolar junction; dorsum of propodeum with standing hairs; first gastral tergite with standing hairs evenly distributed throughout.

Diagnostic comments
As noted in the description of N. denticulatus, the latter, N. innocens and N. stramineus are morphologically relatively close.Nesomyrmex innocens and N. stramineus differ from N. denticulatus by generally smaller body size, smaller eyes with less ommatidia, and a subpetiolar process without a long cuticular flange running back to the postpetiolar junction.The separation of N. innocens and N. stramineus is a bit more difficult, as already mentioned by Bolton (1982).Nesomyrmex innocens has shorter and thicker propodeal spines and a lower and thicker petiolar node compared to N. stramineus.It is not clear at the European Journal of Taxonomy 258: 1-31 (2017) moment whether or not these character states are sufficient to maintain their heterospecificity in the long term.Bolton (1982) had some doubts about this, too, and it is possible that they represent geographical varieties of the same species.However, at present, based on the scarcity of the material, especially of N. innocens, we treat them as two different species.

Biology
Based on the limited data available, N. innocens nests in the stem of trees.

Distribution and biology
This species is only known from very few specimens, collected from the D.R. Congo and Kenya.

Diagnosis
The following character combination distinguishes N. stramineus from the other species of the group: eyes with 7-9 ommatidia in longest row; in profile mesosomal dorsum with conspicuously impressed metanotal groove; propodeal spines relatively long and thin, several times longer than their basal width; in profile petiolar node high, rectangular nodiform, appearing around twice as high as long; in dorsal view petiolar node laterally denticulate; subpetiolar process without a long cuticular flange running back to the postpetiolar junction; dorsum of propodeum with standing hairs; first gastral tergite with standing hairs evenly distributed throughout.

Diagnostic comments
As pointed out above, N. stramineus is very close to N. denticulatus and N. innocens.For more details on its differentiation from them we refer to the species account of N. innocens.

Biology
Nesomyrmex stramineus was sampled in savannah woodlands and Afromontane forests, where it lives in dead wood on trees (Mbanyana & Robertson 2008).

Distribution
This species occurs only in South Africa and Swaziland.It seems to be rather rare since it is only known from a few collection events.

Discussion
As already mentioned above, initially Bolton (1982) revised the Afrotropical Nesomyrmex fauna for the whole region, and more recently Mbanyana & Robertson (2008) for South Africa.Despite the existence of these revisions, there were no clear delimitations of Nesomyrmex species groups for the region prior to this study.Bolton (1982) discussed several assemblages of species that shared some morphological characters, but he did not formally define any groups or complexes.In their revision of South African Nesomyrmex, Mbanyana & Robertson (2008) provide brief species group definitions for the two groups encountered in South Africa: the N. angulatus and N. simoni groups.However, they only cover the South African species and omit the remainder of the Afrotropical fauna.In this study, we provide a first assessment of the entire Afrotropical fauna, propose species groups, and provide illustrated identification tools for all groups and most species with the exception of the species of the N. simoni group, which was extensively revised in Mbanyana & Robertson (2008).Nevertheless, the species groups proposed here are based on morphology alone, and should be treated as taxonomic convenience groups rather than phylogenetic entities.It is still likely that some or all represent monophyletic clades, but this can only be assessed in detail through a thorough comprehensive phylogenetic study that combines morphological with molecular data.
: EL = Eye length: maximum diameter of compound eye measured in oblique lateral view HL = Head length: maximum distance from the midpoint of the anterior clypeal margin to the midpoint of the posterior margin of the head, measured in full-face view.Impressions on the anterior clypeal margin and the posterior head margin reduce head length HW = Head width: width of the head directly behind the eyes measured in full-face view PH = Pronotal height: maximum height of the pronotum measured in lateral view PPH = Postpetiole height: maximum height of the postpetiole measured in lateral view PPL = Postpetiole length: maximum length of the postpetiole measured in dorsal view PPW = Postpetiole width: maximum width of the postpetiole measured in dorsal view PSL = Propodeal spine length: in dorsofrontal view the tip of the measured spine, its base, and the centre of the propodeal concavity between the spines must all be in focus.Using a dual-axis micrometre the spine length is measured from the tip of the spine to a virtual point at its base where the spine axis meets orthogonally with a line leading to the median point of the concavity.PTH = Petiolar node height: maximum height of the petiolar node measured in lateral view from the highest (median) point of the node to the ventral outline.The measuring line is placed at an orthogonal angle to the ventral outline of the node PTL = Petiolar node length: maximum length of the dorsal face of the petiolar node from the anterodorsal to the posterodorsal angle, measured in dorsal view excluding the peduncle PTW = Petiolar node width: maximum width of the dorsal face of the petiolar node measured in dorsal view PW = Pronotal width: maximum width of the pronotum measured in dorsal view SL = Scape length: maximum scape length excluding basal condyle and neck WL = Weber's length: diagonal length of the mesosoma in lateral view from the posteroventral margin of propodeal lobe to the anterior-most point of pronotal slope, excluding the neck mesosoma index: PW / WL × 100 LMI = Lateral mesosoma index: PH / WL × 100 PSLI = Propodeal spine index: PSL / HL × 100 LPeI = Lateral petiole index: PTL / PTH × 100 DPeI = Dorsal petiole index: PTW / PTL × 100 LPpI = Lateral postpetiole index: PPL / PPH × 100 DPpI = Dorsal postpetiole index: PPW / PPL × 100 PPI = Postpetiole index: PPW / PTW × 100 HITA GARCIA F. et al., Taxonomy of the ant genus Nesomyrmex in the Afrotropical region

Fig. 1 .
Fig. 1.Schematic line drawings of Nesomyrmex inhaca sp.nov., illustrating the measurements used.A. Body in profile with measuring lines for EL, WL, PH, PTH and PPH.B. Mesosoma in dorsal view with measuring line for PW. C. Petiole and postpetiole in dorsal view with measuring lines for PTL, PTW, PPL and PPW.D. Head in full-face view with measuring lines for HL, HW and SL.E. Dorsocaudal view of the propodeum with measuring line for PSL.

European
Fig. 5. Nesomyrmex cataulacoides (Snelling, 1992) (CASENT0178300).A. Body in profile view.B. Body in dorsal view.C. Head in full-face view.D. Map of Africa and Madagascar showing currently known distribution.
Fig. 14.Nesomyrmex angulatus (Mayr, 1862) (CASENT0922010).A. Body in profile view.B. Body in dorsal view.C. Head in full-face view.D. Map of Africa and Madagascar showing currently known distribution.
Fig. 15.Nesomyrmex denticulatus (Mayr, 1901) (CASENT0914923).A. Body in profile view.B. Body in dorsal view.C. Head in full-face view.D. Map of Africa and Madagascar showing currently known distribution.
Fig. 18.Nesomyrmex inhaca sp.nov., holotype (MCZ-ENT00593557). A. Body in profile view.B. Body in dorsal view.C. Head in full-face view.D. Map of Africa and Madagascar showing currently known distribution and type locality (black and white star symbol).
Fig. 19.Nesomyrmex innocens (Forel, 1913) (CASENT0906195).A. Body in profile view.B. Body in dorsal view.C. Head in full-face view.D. Map of Africa and Madagascar showing currently known distribution.
Fig. 20.Nesomyrmex stramineus (Arnold, 1948) (CASENT0922011).A. Body in profile view.B. Body in dorsal view.C. Head in full-face view.D. Map of Africa and Madagascar showing currently known distribution.

Review of Afrotropical Nesomyrmex species groups Synoptic list of Afrotropical Nesomyrmex species Nesomyrmex angulatus species group Nesomyrmex angulatus
Taxonomy of the ant genus Nesomyrmex in the Afrotropical region