Pachycondyla tavaratra Rakotonirina and Fisher

Rakotonirina, J. C. & B. L. Fisher, 2013, Revision of the Pachycondyla wasmannii - group (Hymenoptera: Formicidae) from the Malagasy region, Zootaxa 3609, pp. 101-141 : 128-129

Pachycondyla tavaratra Rakotonirina and Fisher , sp. n.

(Figures 3, 38-39, 62)

Holotype worker: Antsiranana, Forêt de Binara, 9.1 km 233° SW Daraina, -13.26333, 49.60333, 650-800 m, under stone, rainforest, 4 Oct 2003 (B.L. Fisher et al.), collection code: BLF09750, specimen code: CASENT0077442 (CASC).

Paratypes: 4 workers with the same data as holotype but specimen coded: CASENT0077438, CASENT0077440, CASENT0247228, CASENT0247229 (BMNH, MHNG, CASC).

Worker diagnosis:

Larger species (HW: 2.49-3.13 mm), antennal scape reaching the posterior margin of head; anterior margin of clypeus broadly triangular; eyes extending beyond the lateral border of head; dorsum of head and mesosoma finely striate, with sparse punctures; stout erect hairs on dorsum of mesosoma and petiole node erected relative to the body surface.

Worker measurements (n=7): HL: 3.05-3.13, HW: 2.55-2.73, CI: 84-88, SL: 1.91-2.09, SI: 99-104, PW: 1.91-2.09, WL: 4.11-4.46, NL: 1.35-1.50, NW: 1.35-1.62, NH: 1.67-1.85, DNI: 100-114, LNI: 116-130.

Description

Worker. Head approximately longer than broad, sides convex and broadest around level of eyes, posterior cephalic margin almost straight. Eyes generally large, breaking outline of sides of the head. Scape elongate, reaching posterior margin of head. Anterior margin of clypeus projecting into triangular median lobe, which makes a blunt angle with mandibular surface when head is viewed in profile. Mandibular masticatory margins armed with eight to nine teeth and denticles. In profile, outline of dorsum of mesosoma forming an uninterrupted convexity, with rounded angle at junction of propodeal dorsum and declivitous surface; declivitous surface is very inclined anteriorly and has imperceptibly visible lateral margins. Mesopleural sulcus indistinct or absent. With petiole in lateral view, node thick, and junction of anterior face and dorsum rounded, whereas dorsum and posterior face meet at distinct angle. In dorsal view, anterior face rounded and posterior face truncate. Sculpture resembles that of P. comorensis , head covered with dense striation superimposed with scattered punctures; striation converging from posterolateral portion of head towards midline and level of eyes through frontal lobes.

Mandibles coarsely costate interspersed with piligerous pits. Pronotum with dense and fine costulae, while mesonotum and propodeum are covered with transverse, dense and fine striation or microreticulation. Lateral portion of mesosoma densely, finely reticulate-rugulose or with striation in different directions, interspersed with sparse large punctures. Declivitous surface microreticulate or transversely finely striate. Lateral surface of petiole node and gastral segments microreticulate, their dorsum densely finely costulate to finely microreticulate. Dorsum of body covered with black, stout hairs which tend to be brown on the appendages; with mesosoma viewed from front, these hairs incline towards its midline and are more erect at dorsolateral margin. Slender, brownish hairs present on ventral surface of head, gaster, and coxae. Pubescence abundant on lateral portion of mesosoma, petiole node, and gastral segments, but almost absent from dorsum of propodeum, petiole node, and dorsum of first and anterior half of second gastral segments. Integument black, head and mesosoma with silky brilliance; articulations and apex of appendages reddish.

As for P. comorensis , queen caste is not known for P. tavaratra , but some individual workers collected from several colonies possess single ocelli, which suggests that these workers might have assumed the reproductive role of the queen. Males are not examined in this revision. Research should be undertaken in the future to understand the colony structure and reproductive organization of the species.

Discussion:

Pachycondyla tavaratra is very similar to P. comorensis , but can be distinguished easily by the triangular projection of the anteromedian clypeal margin, the elongate standing erect hairs on the upper surface of the body, and the location of the eyes, which break the outline of the sides of the head.

Distribution and biology:

Pachycondyla tavaratra occurs in northern Madagascar, and was collected mostly from the high altitude rainforests of the PN Montagne d'Ambre and Forêt de Binara (Fig. 62). Rarely has it been recorded from lower altitudes at Andavakoera and Binara forests. This species forages mostly on the ground and generally nests in rotten logs and soil layers or rarely under rocks. Its longer antennal scapes are suggestive of foraging conducted on the forest floor and through leaf litter.

Other material examined:

Antsiranana, PN Montagne d'Ambre, 975 m (G. D. Alpert) (MCZC); PN Montagne d'Ambre, 1000-1100 m (W.L. & D.E. Brown) (MCZC); PN Montagne d'Ambre: 3.6 km 235° SW Joffreville, -12.53444, 49.1795, 925 m, montane rainforest (Fisher, Griswold et al.) (CASC); PN Montagne d'Ambre, Antomboka, -12.50035, 49.175, 885 m, montane rainforest (B.L. Fisher et al.) (CASC); PN Montagne d'Ambre, Antomboka, -12.51269, 49.17807, 970 m, montane rainforest (B.L. Fisher et al.) (CASC); PN Montagne d'Ambre, Crête, -12.58132, 49.13368, 1110 m, montane rainforest (B.L. Fisher et al.) (CASC); PN Montagne d'Ambre, Petit lac, -12.53664, 49.17412, 1130 m, montane rainforest (B.L. Fisher et al.) (CASC); PN Montagne d'Ambre, Pic Bades, -12.5186, 49.18625, 900 m, montane rainforest (B.L. Fisher et al.) (CASC); PN Montagne d'Ambre, Roussettes, -12.52574, 49.17238, 1025 m, montane rainforest (B.L. Fisher et al.) (CASC); F d'Andavakoera, 21.4 km 75° ENE Ambilobe; 4.6 km 356° N Betsiaka, -13.11833, 49.23, 425 m, rainforest (B.L. Fisher et al.) (CASC); F de Binara, 9.1 km 233° SW Daraina, - 13.26333, 49.60333, 650-800 m, rainforest (B.L. Fisher et al.) (CASC); F de Binara, 9.4 km 235° SW Daraina, - 13.26333, 49.6, 1100 m, montane rainforest (B.L. Fisher et al.) (CASC).