Tetramorium vohitra, Garcia & Fisher, 2012

Garcia, Francisco Hita & Fisher, Brian L., 2012, The ant genus Tetramorium Mayr (Hymenoptera: Formicidae) in the Malagasy region — taxonomy of the T. bessonii, T. bonibony, T. dysalum, T. marginatum, T. tsingy, and T. weitzeckeri species groups, Zootaxa 3365, pp. 1-123 : 85-88

Tetramorium vohitra sp. n.

(figs 72, 83, 122, 123, 124)

Holotype worker, MADAGASCAR, Fianarantsoa, Rés. Andringitra , Anjavidilava Forest , 8.5 km SE Antanitotsy, 22.1667 S, 46.9667 E, 1990 m, upper limit of montane forest, sifted litter (leaf mold, rotten wood), collection code BLF01526, 6.III.1997 (B.L. Fisher) ( CASC: CASENT0189167 ) . Paratypes, three workers with same data as holotype except BLF01524 ( CASC: CASENT0189168 ; CASENT0218031) ; two workers from Rés. Andringitra , 38 km S Ambalavao, 22.2 S, 46.9667 E, 1680 m, montane rainforest, canopy moss and leaf litter, collection code BLF01529, 24.X.1993 (B.L. Fisher) ( CASC: CASENT0192260 ); and nine workers from Rés. Andringitra, 38 km S Ambalavao, 22.2 S, 46.9667 E, 1680 m, montane rainforest, sifted litter (leaf mold, rotten wood), collection code BLF00820, 23.X.1993 (B.L. Fisher) ( BMNH: CASENT0247158 ; CASC: CASENT0218033 ; CASENT0218034; CASENT0218037; CASENT0260168) .

Diagnosis

Tetramorium vohitra can be separated from the remainder of the species group by the character combination of: short antennal scapes (SI 71–74); propodeal spines long (PSLI 28–31); petiolar node rounded high nodiform with anterodorsal and posterodorsal margins at approximately same height, dorsum not tapering backwards posteriorly; dorsum of mesosoma with distinctly, longitudinally arranged rugae; erect to suberect pilosity on first gastral tergite.

Description

HL 0.72–0.83 (0.78); HW 0.70–0.84 (0.78); SL 0.52–0.61 (0.57); EL 0.15–0.18 (0.17); PH 0.39–0.45 (0.42); PW 0.50–0.60 (0.55); WL 0.88–1.03 (0.96); PSL 0.21–0.25 (0.23); PTL 0.17–0.19 (0.18); PTH 0.30–0.35 (0.33); PTW 0.21–0.25 (0.23); PPL 0.22–0.26 (0.25); PPH 0.30–0.36 (0.34); PPW 0.31–0.36 (0.34); CI 97–101 (99); SI 71–74 (73); OI 20–22 (21); DMI 55–59 (57); LMI 41–44 (43); PSLI 28–31 (29); PeNI 39–44 (42); LPeI 51–58 (54); DPeI 120–138 (130); PpNI 58–65 (62); LPpI 71–75 (73); DPpI 131–143 (139); PPI 142–152 (147) (ten measured).

Head weakly wider than long to weakly longer than wide (CI 97–101). Anterior clypeal margin with distinct median impression. Frontal carinae well-developed, ending shortly before posterior head margin. Antennal scrobes weak, shallow, and narrow. Antennal scapes short, not reaching posterior head margin (SI 71–74). Eyes comparatively small (OI 22). Mesosomal outline in profile flat to weakly convex, moderately marginate from lateral to dorsal mesosoma; promesonotal suture absent; metanotal groove present but usually weakly developed; mesosoma comparatively stout and high (LMI 41–44). Propodeum armed elongate-triangular to spinose spines (PSLI 28–31); propodeal lobes short, triangular and acute. Petiolar node in profile rounded high nodiform, approximately 1.8 times higher than long (LPeI 51–58), anterior and posterior faces approximately parallel, anterodorsal and posterodorsal angles at about same height, dorsum not tapering backwards posteriorly; node in dorsal view 1.2 to 1.4 times longer than wide (DPeI 120–138). Postpetiole in profile approximately rounded, weakly anteroposteriorly compressed, approximately 1.3 to 1.4 times higher than long (LPpI 71–75), in dorsal view 1.3 to 1.4 times wider than long (DPpI 131–143). Postpetiole in profile approximately as voluminous as petiolar node, in dorsal view approximately 1.4 to 1.5 times wider than petiolar node (PPI 142–152). Mandibles finely longitudinally rugulose; clypeus with distinct median longitudinal ruga and one to three weaker rugulae at each side; cephalic dorsum between frontal carinae with eight to ten moderately regularly arranged longitudinal rugae, most rugae running unbroken to posterior head margin; lateral and ventral head reticulate-rugose to longitudinally rugose, except mostly unsculptured scrobal area; ground sculpture on head faint. Mesosoma laterally and dorsally longitudinally rugose, often with cross-meshes and sometimes moderately irregular, but main direction of sculpture distinctly longitudinal. Petiolar node, postpetiole, and gaster completely unsculptured, smooth, and shining. All dorsal surfaces of body abundant, moderately long, erect pilosity. Head, mesosoma, waist segments, and gaster of uniform brown colour, mandibles, antennae, and legs yellow to very light brown.

Notes

The new species is currently only known from Andringitra. It was found in montane rainforests at high elevations of 1680 to 1990 m, and seems to live in the leaf litter stratum.

Tetramorium vohitra cannot be confused with T. ambatovy since the latter lacks the longitudinal sculpture typical for the group. Also, due to its long propodeal spines (PSLI 28–31), T. vohitra is easily separated from T. macki (PSLI 21–24) and T. orc (PSLI 19–23). As noted in the description of T. robitika , this species and T. vohitra seem fairly similar at first glance, but differ in several important characters, especially mandibular sculpture and propodeal spine length. The spines of T. robitika are significantly shorter (PSLI 20–22) and the mandibles are clearly sculptured while the spines of T. vohitra are longer (PSLI 28–31) and the mandibles are completely unsculptured. Furthermore, the high rounded petiolar node shape with antero- and posterodorsal margins at about the same height without a tapering dorsum and the longer antennal scapes (SI 71–74) seen in T. vohitra are not present in T. dysalum . In the latter species the antennal scapes are shorter (64–69) and the anterodorsal margin of the petiolar node is situated higher than the posterodorsal margin, causing the dorsum to taper markedly backwards posteriorly.

In addition, T. mallenseana has a postpetiole that is approximately 1.7 to 2 times wider than the petiolar node (PPI 168–200), whereas this relationship is less strongly developed in T. vohitra (PPI 142–152). Also, the propodeal spines of T. mallenseana (PSLI 38–43) are much longer than the spines of T. vohitra (PSLI 28–31). At first glance, T. sargina appears morphologically close to T. vohitra , but both differ in gastral pilosity since it is erect to suberect and of moderate length in T. vohitra versus decumbent to subdecumbent and long in T. sargina . The last two species of the group, T. steinheili and T. yammer , have a more transverse petiolar node (DPel 150–172) compared to T. vohitra (DPel 120–139), and also differ in petiolar node shape. The node of T. vohitra is high rounded nodiform in profile with the anterodorsal- and posterodorsal margins at the same height, whereas the node shape in T. steinheili and T. yammer is more squamiform with the anterodorsal margin always slightly situated higher than the posterodorsal margin and the dorsum weakly tapering backwards posteriorly.

Etymology

The epithet vohitra is Malagasy and means "hill", "village", or "mountain". The type locality is located at an altitude of almost 2000 m, and the name of the new species takes this high altitude into account. The species epithet is a noun in apposition and thus invariant.

Material examined

MADAGASCAR: Fianarantsoa, 38 km S Ambalavao, Rés. Andringitra, 22.2 S, 46.96667 E, 1680 m, montane rainforest, 22.–24.X.1993 (B.L. Fisher); Fianarantsoa, Rés. Andringitra, Anjavidilava Forest, 8.5 km SE Antanitotsy, 22.16667 S, 46.96667 E, 1990 m, Philipia forest and mossy forest, upper limit of montane forest, 6.III.1997 (B.L. Fisher).