Leptanilloides, Mann, 1823

Delsinne, Thibaut, Sonet, Gontran & Donoso, David A., 2015, Two new species of Leptanilloides Mann, 1823 (Formicidae: Dorylinae) from the Andes of southern Ecuador, European Journal of Taxonomy 143, pp. 1-35 : 18-22

Leptanilloides sp. ‘Male 4’ (unassociated to workers)

Figs 8 A–C, 9A–B, 10A–B

Material examined

ECUADOR: 1 ♂, Zamora-Chinchipe Prov., Reserva Biológica San Francisco, entrance of the T1 trail, 1920 m, 3°58’44.09” S, 79°05’8.26” W, 16–29 Mar. 2011, Malaise trap, coll. Thibaut Delsinne and Tania Milena Arias-Penna (QCAZ, sc 4870101). GenBank accession number: KT601704 .

Measurements (in mm) and indices

HW 0.34, HL 0.31, SL 0.24, LAII 0.07, LAIII 0.09, LAIV 0.09, LAXIII 0.17, EL 0.13, MaL 0.16, PrW 0.33, WL 0.66, MH 0.36, PL 0.12, PW 0.11, PPL 0.33, PPW 0.33, AivL 0.13, AivW 0.33, FFeL 0.36, FFeW 0.06, HFeL 0.49, HTL 0.4, CI 110.71, SI 70.97, PI 90.91, MI 54.24.

Description

HEAD. Broader than long, with large convex eye that occupies anterior half of side of head. Mandible slender, falcate, twisted at apex, overlapping at closure ( Fig. 8A ). Basal and masticatory margins strongly concave, separated by well-developed tooth. External margin straight along basal and medial lengths but strongly bent at apex. Mandible longer than eye length. Lateroclypeal tooth and hypostomal tooth lacking, clypeus short and transverse, with narrow clypeal lamella (apron). Antennal socket horizontal and exposed, located at anterior clypeal margin, margin not projecting anteriorly beyond ventral articulation with labrum. Antenna 13-segmented, each segment longer than wide, with second segment shortest. Scape of moderate length, 1.5 times longer than length of ultimate antennal segment. Scape length nearly four times length of second antennal segment. Lateral ocellus separated from median ocellus by its diameter. Distance between lateral ocelli similar to distance between median and lateral ocellus; as a result, ocelli forming equilateral triangle.

MESOSOMA. Pronotum U-shaped in dorsal view and reduced anteromedially to thin horizontal strip, set below level of dorsally protruding mesonotum and triangular in lateral view, with pointed posterior apex directed towards wing base. Mesoscutum lacking notaulus. Parapsidal line not discerned, apparently absent. Axillae depressed, not meeting medially, connected by narrow furrow; tegula very small and inconspicuous. Mesopleuron lacking oblique transverse sulcus and hence not divided into anepisternum and katepisternum. Transcutal sulcus deeply impressed. Mesoscutum and mesoscutellum prominently bulging, in lateral view. Metapleural gland not discernable. Propodeum rounded in profile, with dorsal and declivous faces only poorly differentiated; dorsal surface somewhat shorter than declivous. Propodeal spiracle small, circular, positioned slightly above midheight of propodeum and slightly posterior to metanotum. Leg slender, mid tibia with one simple and hind tibia with one simple spur (observed under 50× magnification), pretarsal claw lacking preapical tooth.

WINGS ( Fig. 9 A–B). With relatively well-developed venation (for Leptanilloides ). Forewing with C present, tubular and pigmented. Sc+R approximated to wing margin, very narrow. Sc+R 1 in line with Sc+R, tubular. Pterostigma well-marked. M+Cu tubular and pigmented, curved towards posterior wing margin before division. Rs·f1 nebulous. M·f1 pigmented, tubular. Rs+M, Rs·f2, and Rs·f3 all joined, tubular and pigmented. 1r-rs absent. 2r-rs present, tubular and pigmented. Rs·f4 and Rs·f5 joined and not differentiated in absence of 2rs-m. Rs·f4&Rs·f5 partly tubular, then nebulous, terminating before wing margin. M and Cu diverging at cu-a. Free abscissa of M partly nebulous, then spectral, very weakly visible, joining to Rs+M&Rs·f2&Rs·f3. Abscissa of Cu joined, nebulous throughout most of length and continuing as spectral. Vein A tubular, joining cu-a at obtuse angle and confluent with Rs+M, apparently absent beyond cu-a. Posterior margin of fore wing with fold where hamuli attach, narrow, conspicuous. Hindwing with C present, narrow and faint. Anterior hindwing margin with small differentiated pigmentation area located in distal half of wing. Three hamuli originate in pigmented region. Sc+R present, nebulous, almost reaching third of wing length. Sc+R1 absent. Rs·f1&Rs·f2 partly nebulous, then spectral. Jugal lobe absent.

METASOMA. Slender in lateral view, obovate in dorsal view, widest at abdominal segment V. Petiole (abdominal segment II) longer than high or wide, rectangular in dorsal view, with convex lateral margin, ovate in lateral view, and weakly constricted posteriorly, helcium thus apparently quite broad. Petiolar spiracle located on anterior third of segment, near anterodorsal extremity. Abdominal segment III three times larger than petiole at its maximum width, not developed as postpetiole nor separated from abdominal segment IV by marked constriction. Abdominal spiracle III located on anterior third of tergite. Abdominal segments II and III with tergosternal fusion. Abdominal segment IV and succeeding segments lacking tergosternal fusion. Spiracle present on anterior third of tergite IV. Abdominal segments V and VI not separated from succeeding segments by constrictions. Abdominal spiracles V and VI indiscernible. Abdominal tergite VIII (pygidium) small and simple but visible dorsally, not wholly covered by abdominal tergite VII.

GENITALIA ( Fig. 10 A–B). Pygostyle absent. Abdominal sternite IX (subgenital plate) with posterior margin broadly and deeply concave but not bifurcate. Basal ring present, not hypertrophied. Paramere relatively small, harpago rounded at apex; paramere shorter than petiole length. Volsella a simple, broad lobe, lacking differentiated cuspis. Aedeagus subequal in length to paramere and volsella, simple, narrow, distally spatulate.

PILOSITY AND SCULPTURE. Integument mostly smooth and shiny, with scattered piligerous punctures. Pilosity common on most of body, suberect to decumbent. Color light brown, head and metasoma past abdominal segment III slightly darker. Appendages (antennae, mandibles, legs) lighter than body.

Distribution

Only known from the sampling locality.

Remarks

The male (specimen code 4870101) collected in southern Ecuador is easily distinguished from any other leptanilloid males (either of Leptanilloides or Amyrmex species, males of all species of Asphinctanilloides being unknown) by the unique shape of its mandible. We did not give it a specific name because it is not associated with workers. However, we called it ‘Male 4’ to indicate that it is different from the three males (‘Male 1’ to ‘Male 3’) described in Borowiec & Longino (2011), which are also without specific names.

The wing venation of ‘Male 4’ is relatively similar to that of ‘Male 3’ in Borowiec & Longino (2011), except that the free abscissa of M on the forewing joins Rs+M&Rs·f2&Rs·f3 (not joining in ‘Male 3’) and Sc+R1 is not visible on the hindwing (present as a short nebulous stub in ‘Male 3’). ‘Males 1 and 2’ of Borowiec & Longino (2011) have more reduced venation, as do the males of Amyrmex ( Ward & Brady 2009) . The forewing venation of L. mckennae and L. nubecula is also closely similar but, in these species, veins M and Cu diverge distal to crossvein cu-a (diverging at cu-a in ‘Male 4’). Table 1 lists informative characters to separate leptanilloid males.

DNA results

The COI sequences of the two new species and ‘Male 4’ differ significantly from each other (p-distances ranging from 18.8 to 21.7%) ( Fig. 11 ). They also diverge (18–21.8%) from the other Leptanilloides DNA barcodes available in BOLD (6 specimens, 2 species: L. gracilis from the L. biconstricta speciesgroup and L. nubecula from the L. legionaria species-group).

Our phylogenetic analyses constructed on the basis of the nuclear gene Wg support one clade consisting of L. prometea sp. nov., L. femoralis , L. gracilis and Amyrmex sp. and another clade composed of L. nubecula , L. nomada and L. mckennae . Both clades are supported by bootstrap values of 98% and 99% in the neighbour-joining tree, 97% and 100% in the most parsimonious tree, 83% and 100% in the tree with maximum likelihood and by posterior probabilities of 1 in the tree built with Bayesian inference ( Fig. 12 ).

Figures

Fig.8.Leptanilloides‘Male4’(specimencode4870101) from southern Ecuador. A. Head in full face view. B. Habitus in dorsal view. C. Habitus in lateral view.

Fig. 9. Wings of Leptanilloides ‘Male 4’ (specimen code 4870101) and terminology used in the description. A. Forewing. B. Hindwing. Abbreviations: 2r-rs = second radial-radial sector crossvein, A = anal vein, C = costal vein, Cu = cubital vein, cu-a = cubital-anal crossvein, M = medial vein, M·f1 = first free abscissa of medial vein, M+Cu = fused medial-cubital veins, Pst = pterostigma, Rs+M = fused medial and radial sector veins, Rs = radial sector, Rs·f1 (to Rs·f5) = first (to fifth) free abscissa of radial sector vein, Sc+R = fused subcostal and radial veins, Sc+R1: fused subcostal and first radial veins.

Fig. 10. Genitalia of Leptanilloides ‘Male 4’ (specimen code 4870101). A. In posterior view. B. In ventral view.

Fig. 11. Neighbour-joining tree showing p-distances among DNA sequences of the mitochondrial COI barcode fragment obtained for all specimens of Leptanilloides Mann, 1823 sequenced here and available in GenBank and BOLD. The tree was rooted with a COI sequence of Cylindromyrmex striatus Mayr, 1870 (GenBank accession number AY233723). Labels provide species identifications and field IDs (in bold) or GenBank or BOLD numbers. Values at nodes indicate bootstrap support only if it was above 80%.

Fig. 12. Neighbour-joining tree showing p-distances among DNA sequences of the wingless nuclear marker obtained for specimens of Leptanilloides Mann, 1823, Amyrmex Kusnezov, 1953 and Cylindromyrmex Mayr, 1870 (as outgroup), available in GenBank and sequenced here (specimen code 4052311). Labels provide species identifications and field IDs (in bold) or GenBank or BOLD numbers. Values at nodes correspond to the bootstrap values (%) and posterior probabilities obtained in the Neighbourjoining/parsimony/maximum likelihood/Bayesian inference analyses. Bootstrap values <80% and posterior probabilities <0.95 are not indicated.