Leptanilloidinae

Borowiec, Marek L. & Longino, John T., 2011, Three new species and reassessment of the rare Neotropical ant genus Leptanilloides (Hymenoptera, Formicidae, Leptanilloidinae), ZooKeys 133, pp. 19-48 : 33-36

Leptanilloidinae male 1 Figure 6 A–F

Material examined.

MEXICO, Chiapas: 2km SE Custepec, 15.72099°, −92.95106° ± 5m, 1495m, 17-24 May 2008 (LLAMA#Ma-A-02-1-02); Nahá, 16.94917°, −91.59476° ± 11m, 960m, 9-13 June 2008 (LLAMA#Ma-A-07-2-02); GUATEMALA, Izabal: 5km NW Morales, 15.51341°, −88.86616° ± 8m, 245m, 16-20 May 2009 (LLAMA#Ma-B-04-2-01); 5km NW Morales, 15.51351°, −88.86647° ± 7m, 245m, 16-20 May 2009 (LLAMA#Ma-B-04-2-02); Petén: Cerro Cahuí, 17.00044°, −89.70346° ± 5m, 140m, 22-25 May 2009 (LLAMA#Ma-B-05-1-02); Parq. Nac. Tikal, 17.24433°, −89.62201° ± 6m, 270m, 22-25 May 2009 (LLAMA#Ma-B-05-2-02); 13km NW Machaquilá, 16.44491°, −89.55136° ± 6m, 380m, 27-30 May 2009 (LLAMA#Ma-B-06-1-01); 13km NW Machaquilá, 16.44661°, −89.54939° ± 8m, 400m, 27-30 May 2009 (LLAMA#Ma-B-06-1-02); 4.5km WNW Machaquilá, 16.40112°, −89.48697° ± 13m, 415m, 27-30 May 2009 (LLAMA#Ma-B-06-2-02); Sacatepéquez: 5km SE Antigua, 14.53725°, −90.69475° ± 4m, 2125m, 10-13 June 2009 (LLAMA#Ma-B-08-1-01); 5km SE Antigua, 14.53650°, −90.69483° ± 4m, 2145m, 10-13 June 2009 (LLAMA#Ma-B-08-1-02); 5km SE Antigua, 14.52846°, −90.68874° ± 6m, 2335m, 10-13 June 2009 (LLAMA#Ma-B-08-2-01); Suchitepéquez: 4km S Vol. Atitlán, 14.54804°, −91.19108° ± 7m, 1580m, 15-18 June 2009 (LLAMA#Ma-B-09-1-01); 4km S Vol. Atitlán, 14.54807°, −91.19188° ± 4m, 1575m, 14-18 June 2009 (LLAMA#Ma-B-09-1-02); 4km S Vol. Atitlán, 14.54852°, −91.19331° ± 7m, 1590m, 14-18 June 2009 (LLAMA#Ma-B-09-2-01); HONDURAS, Olancho: PN La Muralla, 15.09490°, −86.73987° ± 10m, 1410m, 2-5 May 2010 (LLAMA#Ma-C-01-2-02); PN La Muralla, 15.09721°, −86.73840° ± 30m, 1480m, 2-5 May 2010 (LLAMA#Ma-C-01-3-01); Comayagua: PN Cerro Azul Meambar, 14.86987°, −87.89885° ± 10m, 1150m, 20-23 May 2010 (LLAMA#Ma-C-04-2-01); Cortés: PN Cusuco, 15.48898°, −88.23707° ± 10m, 1260m, 30 May– 3 June 2010 (LLAMA#Ma-C-06-1-01); PN Cusuco, 15.48839°, −88.23592° ± 10m, 1260m, 30 May– 3 June 2010 (LLAMA#Ma-C-06-1-02). COSTA RICA, Guanacaste: Santa Rosa Nat. Park, 10.85°, −85.62° ± 2km, 300m, 21 February 2003 (J. S. Noyes) [JTLC000004338].

Measurements (9 measured): HW 0.25-0.31, HL 0.18-0.24, EL 0.09-0.12, SL 0.09-0.012, LAII 0.05-0.07, LAIII 0.04-0.06, LAIV 0.04-0.07, LAXIII 0.10-0.14, MH 0.23 -0.37, ML 0.38-0.54, PrW 0.18-0.26, PW 0.07-0.10, PL 0.07-0.10, AIIIW 0.16-0.21, AIIIL 0.07-0.12, AIVW 0.15-0.23, AIVL 0.10-0.12, FFeW 0.04-0.06, FFeL 0.20-0.29, HFeL 0.22-0.30, HTiL 0.23-0.34, CI 115-130, PI 82-121, MI 60-71.

Description.

Headbroader than long, with large convex eyes that occupy almost half of the sides of head. Mandible slender and falcate with blunt apex, without differentiated masticatory margin, edentate. External margin of mandible more or less evenly curved along its length. Mandible tips crossing at closure, mandible longer than eye length. Lateroclypeal teeth and hypostomal teeth lacking, clypeus short and transverse, without visible clypeal lamella (apron). Antennal sockets horizontal and exposed, located at the anterior clypeal margin that is projecting anteriorly beyond ventral articulation with labrum. Antenna 13-segmented, each segment longer than wide, with second, third and fourth segments subequal in length. Scape of moderate length, subequal to the length of ultimate antennal segment. Scape about twice the length of the second antennal segment, and about the combined length of the second and third antennal segments. Lateral ocellus separated from median ocellus by little more than its diameter. Distance between lateral ocelli little greater than between median and lateral ocellus and ocelli forming almost equilateral triangle. Mesosomawith distinctive pronotum: U-shaped in dorsal view and reduced anteromedially to a thin horizontal strip, set below the level of the dorsally protruding mesonotum and triangular in lateral view, with pointed posterior apex directed towards the wing base. Mesoscutum lacking notauli and parapsidal lines not discernable. Axillae depressed, not meeting medially, connected by a narrow furrow. Tegula very small and inconspicuous. Mesopleuron lacking oblique transverse sulcus and hence not divided into anepisternum and katepisternum. Mesoscutellum prominently bulging, as seen in lateral view. Metapleural gland not discernable. Propodeum with dorsal and declivous surfaces not differentiated, evenly rounded. Propodeal spiracle small, circular, positioned slightly below midheight of propodeum and slightly posterior to the midlength. Legs slender, mesotibia and metatibia each with two simple spurs, pretarsal claw lacking preapical tooth. Wingwith extremely reduced venation. Fore wing with C present, tubular and weakly pigmented. Sc+R very closely approximated to the wing margin, very narrow, compressed vertically, the most apparent vein on forewing. Sc+R1 region not differentiated in absence of Rs·f1 but differing from rest of vein by not being conspicuously vertically compressed; in line with Sc+R, nebulous. Pterostigma not marked. R1·f3 absent. M+Cu nebulous and inconspicuous, slightly curved towards posterior wing margin before division. Rs·f1 absent. M·f1, Rs+M, Rs·f2 and Rs·f3 all joined, not differentiated, tubular or partially nebulous. 1r-rs absent. 2r-rs present, spectral. Rs·f4 and Rs·f5 joined and not differentiated in the absence of 2rs-m. Rs·f4&f5 nebulous and poorly visible, terminating before wing margin. Free abscissae of M absent. Abscissae of Cu joined, initially nebulous, continuing throughout most of the length as spectral. Vein A tubular, joining cu-a at a very obtuse angle and confluent with Rs+M, apparently absent beyond cu-a, although weak flexion at the posterior wing margin can be interpreted as spectral A·f2&f3. Posterior margin of fore wing with narrow, conspicuous fold where hamuli attach. Hind wing with C present, tubular, reaching about fourth of wing length. Anterior margin of hind wing past midlength with a conspicuous dark stigma. Two hamuli originate in the region of the stigma. Jugal lobe absent. Metasoma slender in lateral view, obovate in dorsal view, widest at abdominal segment IV. Petiole (abdominal segment II) subquadrate in lateral view, about as long as high or wide, and only weakly constricted posteriorly, the helcium thus apparently quite broad. Petiolar spiracle located on anterior third of the segment, near anterodorsal extremity; abdominal segment III larger than petiole, and not developed as postpetiole nor separated from abdominal segment IV by a marked constriction. Abdominal spiracle III located on anterior third of tergite. Petiole and abdominal segment III with tergosternal fusion. Abdominal segment IV and succeeding segments lacking tergosternal fusion. Segment IV with weakly differentiated presclerites. Spiracle present on anterior third of tergite IV. Abdominal segments V and VI lacking well differentiated presclerites, and not separated from succeeding segments by constrictions. Abdominal spiracles V and VI not discernable in specimens examined but possibly present at anterior margins of respective tergites. Abdominal tergite VIII (pygidium) small and simple but visible dorsally, not wholly covered by abdominal tergite VII. Pygostyli absent. Abdominal sternite IX (subgenital plate) with posterior margin broadly and deeply concave but not bifurcate. Basal ring present, not hypertrophied. Paramere small and slender with pointed, slightly outcurved apex of harpago. Paramere little longer than petiole length. Volsella a simple, narrow and elongate lobe, lacking differentiated cuspis, distally pointed and slightly outcurved. Aedeagus little longer than paramere and volsella, simple, narrow, distally spatulate. Body size very small. Integument mostly smooth and shiny, with scattered piligerous punctures. Pilosity common on most of body, suberect to decumbent. Color light yellowish-brown, head and posterior margins of abdominal segments IV–VII darker, appendages (antennae, mandibles, legs) lighter.

Discussion.

Project LLAMA (Leaf Litter Arthropods of MesoAmerica) is an arthropod biodiversity inventory project carrying out a structured sampling program at sites from southern Mexico (Chiapas) to Nicaragua. The focus is on mature mesophyll forest at multiple elevations. Four days are spent sampling at each study site, and one of the methods is to erect four Malaise traps for the four days. Sampling has been carried out in May and June, 2008 to 2010. The diminutive Leptanilloides male described here is surprisingly common in the Malaise samples, occurring at many of the study sites and across a great range of elevations (these specimens temporarily reside in the personal collections of Borowiec and Longino, ultimately to be deposited in major institutional collections). They have been found in the Sierra de Chiapas (near the type locality of Leptanilloides gracilis ), in the lower elevation Lacandón rainforests of northern Chiapas, in the Petén region of Guatemala, in both lowland and montane regions of central Guatemala, and in montane regions of Honduras. When they occur at a site, they are typically found in more than one of the Malaise traps, but usually no more than about five males per trap in a 4-day sample. They are very easily overlooked because of their similarity, in both size and degree of sclerotization, to small nematoceran Diptera that are often abundant in Malaise samples.

From hitherto described males of Leptanilloides ( Donoso et al. 2006, Ward 2007, Ward & Brady 2009, this study) and Amyrmex (Ward & Brady 2009) this morphos pecies can be differentiated by a combination of falcate mandibles, small size and extremely reduced wing venation with Rs·f1 and pterostigma absent in fore wing and hind wing venation restricted to a short C stub, as well as the external structure of the genitalia. The falcate mandibles are similar in shape to mandibles of males of Leptanilloides nubecula , but the specimens of male 1 are smaller than the males of Leptanilloides nubecula and apparently have less well developed wing venation. Although Donoso et al. (2006) did not describe wing venation in detail for Leptanilloides nubecula , and we have not examined the male specimens of that species, from the picture given in their treatment (Fig. 26, p. 55) it is clear that the wing venation is much better developed in Leptanilloides nubecula .Rs·f1 can be seen in fore wing and hind wing has a conspicuous Sc+R running almost three fourths of the wing length, while in male 1 both these veins are apparently absent.

The largely sympatric distribution, two simple spurs on mid and hind tibia, overall small size, and relative abundance make these specimens good candidates for the male caste of Leptanilloides gracilis .