Tetraponera hespera, Ward, P. S., 2009

Ward, P. S., 2009, The ant genus Tetraponera in the Afrotropical region: the T. grandidieri group (Hymenoptera: Formicidae)., Journal of Hymenoptera Research 18, pp. 285-304 : 295-296

Tetraponera hespera sp. n.

(Figs 2-4, 6, 9-12, 24)

Tetraponera pswllO; Fisher 2002: 318. Cited in faunal inventory.

Holotype worker. MADAGASCAR Antsiranana : Nosy Be , 4 km ESE Andoany (= Hellville ), 100 m, 13°25'S 48°18'E, 2.v.1989, ex rotten stick on ground, rainforest, P. S. Ward # 10457 ( CASENT0012865 ) ( CASC).

Paratypes. Séries of workers and queens, same locality and date as holotype, elevation 100-200 m (P. S. Ward#10456, 10457, 10459, 10463, 10465, 10470-1) ( BMNH, CASC, MCZC, PSWC, SAMC, UCDC) .

Material Examined.-( BMNH, CASC, MCZC, PSWC, SAMC, UCDC) MADAGASCAR Antsiranana: Ampasindava, Ambilanivy, 3.9 km 181° S Ambaliha, 600 m (Fisher, B. L.; et al.) ; Forêt Antsahabe, 11.4 km 275° W Dairana, 550 m (Fisher, B. L.; et al.) ; Forêt Binara, 9.1 km 233° SW Dairana, 650-800 m (Fisher, B. L.) ; Nosy Be, 4 km ESE Andoany (=Hellville), 100 m (Ward, P. S.) ; Rés. Ankarana, 7 km SE Matsaborimanga, 150 m (Ward, P. S.) ; Rés. Spéc. Ankarana, 13.6 km 192° SSW Anivorano Nord, 210 m (Alpert, G. D.; et al.) ; Rés. Spéc. Ankarana, 13.6 km 192° SSW Anivorano Nord, 210 m (Fisher, B. L.; et al.) ; Rés. Spéc. Ankarana, 22.9 km 224° SW Anivorano Nord, 80 m (Fisher, B. L.; et al) ; R.S. Manongarivo, 10.8 km 229° SW Antanambao, 400 m (Fisher, B. L.) ; R.S. Manongarivo, 12.8 km 228° SW Antanambao, 780 m (Fisher, B. L.) ; Toliara: Ambohijanahary, 34.6 km 314° NW Ambaravaranala, 1100 m (Fisher, В. L.; et al) ; Ambohijanahary, 35.2 km 312° NW Ambaravaranala, 1050 m (Fisher, B. L.; et al.) .

Worker measurements (n = 13). HW 0.95-1.31, HL 1.19-1.55, LHT 1.12-1.53, CI 0.78-0.90, FCI 0.14-0.18, REL 0.30-0.35, REL2 0.35-0.41, SI 0.77-0.83, FI 0.29-0.34, PLI 0.50-0.58, PWI 0.42-0.53.

Worker diagnosis. Similar to T. grandidieri (q.v.). Basal margin of mandible lacking tooth; anterior clypeal margin broadly convex and crenulate, directed forward; head relatively elongate (CI 0.78-0.90); metanotal spiracle visible in lateral view of mesosoma (Fig. 6); dorsal face of propodeum usually broadly convex in posterior view, but more dorsally compressed and subtriangular in one population(see below); standing pilosity and appressed pubescence generally sparse; integument mostly sublucid, with fine coriarious/puncticulate sculpture; body unicolorous yellow-brown or orange-brown, legs usually with contrasting black bands on the distal portions of the femora; banding sometimes weakly developed on the profemur, and absent from ali legs in one population.

Comments. T. hespera représente an assemblage of variably isolated populations in northwestern Madagascar. This species is most readily recognized by its distinctive color pattern: workers are usually a unicolorous yellow-brown or orange-brown, with contrasting black bands on the legs (Fig. 10). In earlier identifications of muséum material I employed a code name for this species: Tetraponera pswllO.

The hespera-like population occupying the Ankarana Massif is divergent in several respects: workers lack the characteristic black leg banding (Fig. 12) and they have a dorsally narrowed propodeum that appears more or less triangular in shape when seen in posterior view (Fig. 3), in contrast to the broadly convex propodeum seen in other populations of T. hespera (Fig. 4) and in the rest of the T. grandidieri group. Although I considered treating the Ankarana form as a different species, severa! observations argued against this.

(1) It is strictly allopatric to the more typical morph of Г. hespera , so there is no "test" of species distinctness in sympatry.

(2) Samples from tropical dry forest at Forêt Antsahabe, 60 km southeast of Ankarana, have black leg banding but the propodeum tends to be intermediate in shape between the Ankarana morph and more typical T. hespera . (3) A worker ( BLF 10881; CASENT0053718) from another nearby locality, Forêt Binara, has black leg banding and a broadly convex propodeal dorsum -yet it is genetically identical at the mitochondrial COI locus to a worker from Forêt Antsahabe. The COI data indicate that ali three populations (Ankarana, Antsahabe and Binara) are closely related and form a clade that is sister to T. hespera + T. hirsuta , but with combined nuclear gene séquences the three populations do not form a clade; instead, they are paraphyletic with respect to T. hirsuta . Thus, recognizing the Ankarana form as a distinct species would require an arbitrary division along a gradient of differentiated allopatric populations.

Distribution and biology. This species is found in northwestern Madagascar, with an isolated population at Ambohijanahary in centrai western Madagascar (Fig. 24). It occurs sympatrically with T. grandidieri, T. hirsuta and T. merita at one or more localities. Most populations of T. hespera are in seasonally dry rainforest, where colonies tend to nest near the ground level, usually in rotten sticks. One colony from the type locality ( PSW 10456) was nesting in an earthworm cast on the ground. As in T. grandidieri , observed colony sizes are small (4-36 workers).