Myrmoteras

Agosti, D., 1992, Revision of the ant genus Myrmoteras in the Malay Archipelago (Hymenoptera, Formicidae)., Revue Suisse de Zoologie 99, pp. 405-429: 407-411

publication ID

http://doi.org/ 10.5281/zenodo.10693

DOI

http://doi.org/10.5281/zenodo.5640708

persistent identifier

http://treatment.plazi.org/id/498720C1-AC3E-F043-38B4-183A00120E49

treatment provided by

Donat

scientific name

Myrmoteras
status

 

Myrmoteras   Forel

Myrmoteras   Forel, 1893:607. Type species Myrmoteras binghami Forel   , by monotypy. Diagnosis. Worker.

Formicine ant with the following diagnostic characters.

1 Mandibles long (longer than head length), subparallel with a distinctive dentition pattern with the apical teeth the longest (Figs 7-10).

2 The mandibles can be opened up to 270°.

3 Maxillary palps not exceeding half the distance between the buccal opening and the foramen magnum.

4 Clypeus anteriorly bilobed. antero-medially emarginate (Fig. 1).

5 Frontal carinae not present, but toruli prominent (Fig. 1).

6 Large eyes (El > 55).

7 Long erect hair present antero-ventral of the eyes.

8 Head posteriorly truncated and with a distinctive transverse lobe (Figs 1-2).

9 Pronotum anteriorly with transverse straight sculpture (Fig. 5).

10 Mesonotum tubular and forming a constriction of the alitrunk (Fig. 6).

11 On the dorsum of the meso- and metanotum restricted hair pattern. A group of symmetrically positioned hairs and the anterior part of the mesonotum and 2 to 6 hairs on the metanotal spiracles, rarely 1 to 2 single hairs on the margins between the two groups.

12 Propodeal spiracle round, situated at some distance from the declivous and the basal face (Fig. 42).

13 Anteriormost point of the metanotal petiolar cavity not crossing a line spanned between the anterionnost points of the metanotal coxal cavities.

14 Petiole squamiforme.

15 First gastral segment of Formica   type (see Agosti, 1991, fig. 4).

16 First gastral tergite much smaller then the second.

17 Hind legs and and antennae with long, scattered, erect pilosity.

18 Mid and hind femora swollen.

Description. The palpal formula is variable, from 6/4 to to 3/3, in most cases 6/4 (44%). The reduction of the terminal segments does not have a very distinct influence on the overall length of the maxillary palps, which generally do not reach beyond the midpoint between the buccal orifice and the foramen magnum.

The frontal sulcus is in most species very distinct and wide, but can be absent, especially in the Myrmoteras   , subgenus.

The coloration is yellowish to dark brown with different brown shades and can be variable in some species.

The diagnostic characters 1. 2, 4, 6 and 8 are very likely autapomorphies of the genus, as they are not present in other formicine genera. These make Myrmoteras   one of the most easily diagnosable monophyletic formicine genera.

v

Phylogeny. Myrmoteras   belongs to the Formica   genus group, based on the construction of the first gastral stemite which is not part of the helcium (Agosti, 1991). The phylogenetic relationships of this genus within the subfamily and within the Formica   genus group are not resolved, but are currently being studied (Agosti, in prep.). Within Myrmoteras   the two sister groups Myrmoteras   s. str. and Myagroteras   can be diagnosed by the following autapomorphies: the labral shape and the presence of trigger hairs, and the frontal sulcus and mandibular bend character respectively (Moffett, 1985). Whereas these two clades are in congruence with the results of this study and additional material from Thailand in MHNG, not all the new species can be placed into Moffett's species groups. For this reason and without the re-assessment of the characters Moffett's species groups have been suppressed.

Distribution. Myrmoteras   is an Indomalayian genus, with some species in Southern India, Sri Lanka, Burma, Thailand, and the islands west of the Wallace Line with the exception of Sulawesi and Lombok (see maps in Moffett, 1985). Within the Malay Archipelago, the subgenus Myrmoteras   is restricted to the West of the Wallace Line and Myagroteras   to the West of Weber's Line.

The fauna of Sulawesi and Lombok deserve special attention. On Lombok brigitteae   is the only species which has been collected so far. It has also been collected in Bali. The fine differences between the two populations have been considered as intraspecific, and indicate that there is a link with the islands west of the Wallace Line based on dispersal.

In contrast, Sulawesi has an isolated fauna which, with its 10 species, is as rich as the fauna of Borneo, but does not share any species with any other islands.

The low number of species found in Sumatra and Java is surprising. Both in Sulawesi and Borneo, wherever the genus Myrmoteras   is present, there are almost always several species to be found. They are not necessarily in exactly the same habitat but rather present at different altitudes. Our collections in Java and Sumatra included the same collecting techniques and sampling strategy as in Sulawesi or in Borneo. It is thus probably an indication that Myrmoteras   might have the highest number of species in Borneo and Sulawesi.

Thailand and W-Malaysia are certainly underrated, with regard to the 13 species here described, an increase of over 70% based on a few collecting sites and limited time. Mainland Asia has to be studied before generalizations can be made.

However, Sulawesi and Lombok might very likely define the Eastern limits of the distribution, as specific collections from Seram, Flores, Timor and the Vogelkop did not reveal any Myrmoteras   species (W.L. Brown, Jr, pers. com.; Agosti, unpubl.). The apparent high degree of endemism, if not contradicted by further collections, would make this genus an ideal object for biogeographic studies.

Biology. The biology of Myrmoteras   ants is virtually unknown. They are elements of the leaf litter fauna in moist tropical forest, from lowland up to montane forests with the highest recorded altitude of a species at 2200 m in Assam. The uniform morphology, especially the head with the two long mandibles, indicate that all the species are predatory on soft bodied insects, which was observed in colonies kept in captivity (Moffett, 1985). Most Myrmoteras   specimens have been collected from leaf litter samples from beneath rotting logs. In one case a Myrmoteras   sp. has been observed on a shrub in the understory. Nests have been found in hollow dead twigs in the litter (Moffett, 1985).

Synopsis of the species of Myrmoteras  

Myrmoteras   subgenus

barbouri Creighton   , 1930. Java, Peninsular Malaysia, Sabah, Sarawak.

= kemneri Wheeler   , 1933.

baslerorum   new species. Sumatra.

binghami Forel   , 1893. Burma, Thailand.

brachygnathum Moffett   , 1985. India.

ceylonicum Gregg, 1956. Sri Lanka.

iriodum Moffett   , 1985. Kalimantan, Sarawak, W-Malaysia.

mjoebergi Wheeler   (in Creighton, 1930). Borneo ( Sarawak?).

scabrum Moffett   , 1985. India.

Myagroteras   subgenus arcoelinae   new species. Sabah

bakeri Wheeler   , 1919. Sabah, W-Malaysia.

brigitteae   new species. Bali, Lombok chondrogastrum Moffett, 1985. Sarawak.  

danieli   new species. Sabah.

diastematum Moffett   , 1985. Sabah, Sarawak.

donisthorpei Wheeler   , 1916. Kalimantan, Sabah, Sarawak.

elfeorum   new species. Sulawesi.

estrudae   new species. Sumatra.

indicum Moffett   , 1985. India.

insulcatum Moffett   , 1985. Luzon.

ivani   new species. Sulawesi.

jacquelineae   new species. Sulawesi.

karnyi Gregg   , 1954. Mentawai Archipelago.

marianneae   new species. Sulawesi.

maudeae   new species. Sulawesi

morowali Moffett   , 1985. Sulawesi.

nicoletteae   new species. Sulawesi.

susanneae   new species. Sulawesi.

tonboli   new species. Sabah.

toro Moffett   , 1985. Sulawesi.

williamsi Wheeler   , 1985. Phillipines.

wolasi Moffett   , 1985. Sulawesi.

Key to workers of Myrmoteras   of the Malay Archipelago

M. karnyi   is not keyed out, as the holotype has not been found in the Zoological Museum in Bogor.

The abbreviation 'Mo' refers to the figures in Moffett 1985, i.e. 'Mo.25' refers to his figure 25.

1. Trigger hairs present, at least one fourth as long as mandible (Fig. 3); the labrum coneshaped, in full frontal view, the insertions of the trigger hairs visible between the bases of the mandibles (Mo5); the apical part of the mandible (last apical tooth) bent ventrally (Fig. 3)................................................................2 ( Myrmoteras   )

- Trigger hairs not present; labrum flat (Mo4); teeth of mandible in the same plain, the apical tooth not bent ventrally (Fig. 4)....................................5 ( Myagroteras   )

2 4 maxillary palps; mesonotum smooth, with only two lateral rugae (Mo 18) mjoebergi   - 5 or 6 maxillary palp segments; mesonotum laterally with reticulate sculpture (Mo 15- 17) which includes at least some dorso ventral rugae (Fig. 41)............................3

3 Dorsal surface of head and pronotum smooth and shining with an iridescent shine; body chestnut, coxae and basal parts of femora brighter....................... baslerorum  

- Dorsal surface of head and pronotum smooth or granulate, and matt; body reddish to yellowish brown; coxae and femora of the same color as alitrunk........................4

4 6 maxiliary palp segments; dorsal surface of head and alitrunk granular; mesonotum strongly constricted (Mo 15)........................................................... barbouri  

- 5 maxillary palp segements; dorsal surface of head and alitrunk smooth and matt; mesonotum as in Mo 17.................................................................... iriodum  

5 Frontal sulcus lacking (Mo33)...................................................... insulcatum  

- Frontal sulcus present (Fig. 1)..................................................................6

6 Occiput of head smooth and shining, at least at the margin of the occiput a distinct change in the sculpture, from distinct sculpture very weak, which is almost impercepatable (in donisthorpei   sometimes the dorso median part with some granular sculpture, but never the lateral parts of the declivitous face) (Fig. 1); sculpture on the dorsum and lateral parts of alitrunk varying from absent to elaborate; in lateral view the dorsal outline of the propodeum anteriorly not angulate (Fig. 12).................. 11

- Posterior face of occiput and pronotum sculptured; in lateral view, alitrunk always with distinct sculpture; the dorsal outline of the propodeum anteriorly with a distinct step (Fig. 6)..............................................................................................7

7 Head in full frontal view longitudinally sculptured, sometimes mixed sculpture but the longitudinal rugae visible in dorso lateral view (Fig. 7); yellowish brown............. 10

- Head in full frontal view finely granulate sculptured (Fig. 1)..............................8

8 Dorsum of pronotum granulate; dorsum of propodeum in lateral view convex and smooth with at most some granular sculpture (Mo44)............................. williamsi  

- Dorsum of pronotum longitudinally sculptured (Fig. 5); dorsum of alitrunk in lateral view flat with longitudinal sculpture (Fig. 6)................................................9

9 Frontal triangle smooth and shining (Mo38); dorsum of pronotum with broad longitudinal rugae; alitrunk with granular sculpture and longitudinal rugae (Mo42); yellow.................................................................................... morowali  

- Frontal triangle granulate (Fig. 1); dorsum of pronotum with reticulate to longitudinal sculpture (Fig. 5); dark redish brown;........................................... jacquelineae  

10 Posterior face of occiput longitudinally sculptured (Mo39); head in full frontal view with distinct longitudinal sculpture (Mo39); dorsum of pronotum with reticulate sculpture........................................................................................tow

- Posterior face of occiput coarsely sculptured (Fig. 7); head in frontal view with longitudinal sculpture which is obscured by granular sculpture (Fig. 7); dorsum of pronotum with a semicircular longitudinal sculpture (Fig. 11).................... elfeorum  

11 Head in full frontal view with frons shining and smooth................................. 12

- Head in full frontal view with frons sculptured.............................................16

12 Dark chestnut brown, coxae and femora bicoloured; TL > 1.50 mm; propodeum smooth and shining, only sometimes with a few low soft transversal rugae on the dorsum of the propodeum (Figs 14, 16. Mo29)............................................. 13

Yellowish, coxae and femorae all one colour; TL 1.50 < mm; propodeum distinctly sculptured (Figs 18, Mo28)....................................................................15

13 Head in full frontal view between the antennal insertions smooth and shining (Mo26); erect hairs up to 0.25 mm ......................................................... diastematum  

Head in full frontal view with longitudinal sculpture between the antennal insertions (Figs 8, 9); hairs on alitrunk shorter than 0.20 mm ........................................ 14

14 Dorsum of pronotum smooth and shining (Fig. 13)................................... tonboli  

- Dorsum of pronotum sculptured as in Fig. 15.................................... arcoelinae  

15 Genae (part ventral of eyes) sculptured, dorsum of mesonotum and propodeum smooth ................................................................................................... ivani  

- Genae not sculptured or at most few short dorsoventral rugae adjacent to the eye; dorsum of mesonotum coriaceous, dorsum of propodeum with transversal sculpture (Mo28)....................................................................................... bakeri  

16 Dorsum of pronotum smooth and shining (Figs 23, 25)................................... 17

- Dorsum of pronotum sculptured (Figs 27, 29).............................................. 18

17 Genae (part ventral of the eye) with longitudinal sculpture; dorsaly of the propodeal spiracles transversally sculptured (Fig. 24)...................................... marianneae  

- Genae at most with some dorsoventral short sculpture adjacent to the eye; dorsum of propodeum without transversal sculpture (Fig. 26)................................. estrudae  

18 Gastral tergites coriaceous.................................................... chondrogastrum  

- Gastral tergites smooth and shining (sometimes obscured by an oily layer)............19

19 Head in frontal view granulate, giving the impression of a longitudinal sculpture, but the lines are built up by individual small granules (Mo32). Dorsum of pronotum and mesonotum granulate (Mo35); dorsum of propodeum smooth and shining or slightly granulate (Mo35)................................................................... donisthorpei  

- Head in frontal view with longitudinal sculpture, the rugae are long and not interrupted (Figs 21, 22).....................................................................................20

20 Whole body yellow to orange red............................................................21

- Whole body dark brown to chestnut.........................................................23

21 Head in full frontal view distinctly, longitudinally sculptured (Figs 22, 31)...........22

- Head in full frontal view very finely, longitudinally sculptured. This is very shiny and is best seen in dorsolateral view (Fig. 21);gula smooth and shining; dorsum of pronotum as in Fig. 27................................................................. brigitteae  

22 On gula few longitudinal rugae; clypeus longitudinally sculptured (Fig. 22); dorsum of pronotum shining and with three circular sculptural elements (Fig. 29); ventral part of the declivity of the propodeum without sculpture.............................. nicoletteae  

- On gula no longitudinal rugae; clypeus with granular sculpture (Mo41); declivitous face of propodeum without sculpture................................................... wolasi  

23 Dorsum of pronotum anteriorly with convergent longitudinal sculpture (Fig. 35) ................................................................................................ danieli  

- Dorsum of pronotum anteriorly without longitudinal sculpture but with a spacious undulating surface (Figs 37, 39).............................................................. 24

24 Dorsum of pronotum with erect hairs which are shorter than a third of the maximum diameter of the front femora (Fig. 37); ventral part of the lateral parts of the mesonotum with a metallic blue shine............................................... maudeae  

- Dorsum of pronotum with erect hairs which are of the same length as the maximum diameter of the front femora (Fig. 39); ventral part of the lateral parts of the mesonotum dark brown............................................................... susanneae  

MHNG

Switzerland, Geneva, Museum d'Histoire Naturelle