Pachycondyla planicornis Rakotonirina and Fisher

Rakotonirina, Jean Claude & Fisher, Brian L., 2013, Revision of the Pachycondyla wasmannii - group (Hymenoptera: Formicidae) from the Malagasy region, Zootaxa 3609 (2), pp. 101-141 : 127-128

Pachycondyla planicornis Rakotonirina and Fisher , sp. n.

( Figures 2 , 5 , 44–45 , 61 )

Holotype worker: Antsiranana, Betaolana Forest, along Bekona River, -14.52996, 49.44039, 880 m, ex rotten log, rainforest, 5 March 2009 (B.L. Fisher et al.), collection code: BLF22566, specimen code: CASENT0151943 (CASC).

Paratypes: 2 workers, same data as holotype but with following specimen codes: CASENT0247232 and CASENT0247233 (CASC, BMNH).

Worker diagnosis:

With head in full-face view, antennal scape not surpassing posterior cephalic margin; dorsum of head and mesosoma not finely striate, dorsum of body with erect slender hairs and pubescence; basal half of antennal scape dorsoventrally flattened, with thin leading edge; lateral portion of hind basitarsus flattened, the basal half of the inner surface concave; dorsal outline of mesosoma not forming a continuous convexity; junction of propodeal dorsum and declivitous surface angulate; petiolar node thick; anterior half of fourth abdominal tergite (gastral tergite 2) mostly smooth and shiny between large punctures.

Worker measurements (n=7): HL: 2.09–2.25, HW: 1.93–2.07, CI: 90–92, SL: 1.42–1.49, SI: 70–75, PW: 1.38–1.50, WL: 2.86–3.02, NL: 0.84–0.98, NW: 1.05–1.23, NH: 1.10–1.22, DNI: 118–127, LNI: 118–149.

Description:

Worker. In frontal view, head longer than broad, broadest on posterior third, posterior margin strongly concave and medially excised, sides converging in front of eyes. Compound eyes large; with head in full-face view, located slightly to the front but still breaking outline of sides of head. Antenna with basally, dorsoventrally flattened scape, and thin leading edge; with head in full-face view, scape broad from base to apex, fairly short and not extending beyond posterior margin. Median lobe of clypeus not projecting anteriorly, anterior margin distinctly truncate and medially notched. Mandibles triangular, armed with eight distinct teeth and denticles. In lateral view, although propodeal declivity on a lower level relative to dorsum of mesosoma, dorsal outline not forming a continuous convexity, with propodeal dorsum joining declivity in distinct angle; mesopleural sulcus either visible or indistinct. Basitarsus of hind legs flattened laterally, basal half of the inner surface noticeably concave. In profile, petiole nodiform, rounded anterodorsally and at distinct angle posterodorsally.

Mandibles coarsely striate with piligerous punctulae. Dorsum of head densely and finely reticulate-rugulose, interspersed with scattered punctures. Dorsal surface of mesosoma coarsely punctate or densely and finely reticulate-rugulose, superimposed with variable-sized punctures; lateral portion with compact and fine reticulaterugulation and scattered punctures; propodeal declivity generally smooth. Dorsal surface of node covered with sparse, large and shallow punctures; sides coarsely, shallowly punctate with effaced rugulation. Gastral tergite smooth and shiny between widely spaced, shallow punctures or with dense, small punctures. Brown, slender, erect hairs and pubescence present on dorsum of head and body. Integument dark brown to black, with lighter shade on appendages.

Queen and male castes are unknown for this species.

Discussion:

Pachycondyla planicornis is very similar to P. cambouei and P. p e r ro t i, but it can be distinguished by the fact that the basal half of its antennal scape is dorsoventrally flattened and its hind tibia is laterally compressed. It is a locally rare species even though its geographical range on Madagascar is quite large.

Distribution and biology:

Pachycondyla planicornis is a rare species, restricted geographically to the mesic forests of eastern Madagascar ( Fig. 61 ). It is only known from lowland forest of the PN Marojejy and Betaolana (along Bekona River) in the northeast of the island, through the sandy forest of Mahavelona (Foulpointe) in the east, to the montane rainforest of the PN Ranomafana in the southeast. Collection data indicate that foraging is carried out on the ground surface, and nests are located mainly in rotten logs.

Other material examined:

Antsiranana: Marojejy, dense forest (J.M. Betsch) (MCZC); PN Marojejy,-14.4382, 49.774, 487 m, rainforest (Rin'Ha, Irwin) (CASC); Makirovana Forest, -14.1707, 49.9541, 415 m, rainforest (B.L. Fisher et al.) (CASC); Fianarantsoa: Belle Vue trail, Ranomafana National Park, -21.2665, 47.42017, 1020 m, mixed tropical forest (R. Harin'Hala) (CASC); Toamasina: Mahavelona (Foulpointe); -17.66667, 49.5, in sandy forest (A. Pauly) (CASC).

Figures

FIGURES 1 – 2. Full-face view of the head showing the length of the antennal scape; Fig. 1: scape surpassing the posterior cephalic margin; Fig. 2: scape not surpassing the posterior cephalic margin.

FIGURES 5 – 6. Antennal scape and leading edge viewed from the back; Fig. 5: basally dorsoventrally flattened and thin in P. planicornis; Fig. 6: subcylindrical and rounded (e. g., P. cambouei).

FIGURES 42 – 47. Full-face view of the head and lateral view of the body of the worker caste. Figs 42 – 43: Pachycondyla perroti, CASENT 0048930; Figs 44 – 45: Pachycondyla planicornis, CASENT 0096369; Figs 46 – 47: Pachycondyla tavaratra, CASENT 0410152.

FIGURES 59 – 64. Distributional maps of Pachycondyla wasmannii - group from the Malagasy region. Fig. 59: P. c o m o re n s i s; Fig. 60: P. p e r ro t i; Fig. 61: P. planicornis; Fig. 62: P. tavaratra; Fig. 63: P. v a z i m b a; Fig. 64: P. wasmannii.