Polyrhachis longipilosa, Jaitrong & Yamane & Noon-Anant, 2023

Jaitrong, Weeyawat, Yamane, Seiki & Noon-Anant, Nawee, 2023, The Thai species of the Polyrhachis (Myrmatopa) flavicornis Smith, 1857 species group, with description of a new species (Hymenoptera, Formicidae Formicinae), Zootaxa 5249 (4), pp. 446-464 : 458-459

Polyrhachis longipilosa sp. nov.

( Fig. 7 )

Holotype. Worker (THNHM-I-26206, THNHM), W Thailand, Kanchanaburi Prov., Thong Pha Phum Dist., Ban Sahakorn Nikhon , dry evergreen forest, canopy, 25 m from ground, 8.XI.2021, W. Jaitrong leg., TH21-WJT-789 . Paratypes: eleven workers (THNHM-I-26207 to THNHM-I-26217, THNHM) same data as holotype .

Measurements and indices (holotype and 11 paratypes). TL 6.05–6.50, HL 1.65–1.68, HW 1.22–1.32, SL 1.91–1.98, PW 0.92–0.99, MTL 1.91–1.98, CI 77–78, SI 150–157.

Description of worker ( Fig. 7 )

Head in full-face view distinctly longer than broad with posterior margin roundly convex. Clypeus in dorsal view broad and weakly convex, its anterior and posterior margins distinctly convex; median portion of anterior clypeal margin with a pair of short teeth, diastema between teeth weakly concave. Mandible subtriangular, masticatory margin with 5 distinct teeth (including basal and apical teeth); basal margin straight, unarmed besides basal tooth. Frontal carinae in full-face view weakly sinuate, and reaching level of mid-length of eye, in profile well elevated. Antennal scape long, clavate, and extending beyond posterior margin of head by at least half of its length. Eye convex, slightly protruding from lateral outline of head and located just posterior to midlength of head laterally.

Mesosoma box-like, its dorsum distinctly marginate laterally along entire length. Pronotum in dorsal view, slightly shorter than broad, slightly narrowed posteriorly, and armed with anterolateral teeth, in profile view pronotum weakly convex dorsal outline; margin between the anterolateral teeth convex; lateral face of pronotum subtriangular. Mesonotum in dorsal view shorter than pronotum, almost as long as broad; mesopleuron in profile rectangular, shorter than high, and almost flat. Propodeal dorsum subrectangular and almost as long as broad; propodeal junction produced as pair of short, blunt, and upward-pointed spines.

Petiolar node (excluding spine) in profile view round and almost as long as high; petiolar spines in dorsal view divergent apical, in lateral view slightly curved backwards, as long as height of petiole; subpetiolar process weakly developed, with convex ventral outline.

Mandible entirely with very fine superficial microsculpture and dull. Vertex and frons of head areolate-rugose, area between frontal carinae areolate-rugose posteriorly and punctate anteriorly; areas between eyes and frontal carinae reticulate-striate. Clypeus, antenna, and legs reticulate. Lateral faces of mesosoma and petiole densely areolaterugose; petiolar spine macropunctate in basal half, while its apical half more weakly sculptured and shiny; pronotum longitudinally finely striate; mesonotum and dorsum of propodeum irregularly striate rather than punctate.

Antennal scape with dense brown standing hairs (most of them longer than maximum width of antennal scape); antennal segments II–XII with short standing hairs; dorsa of head and mesosoma densely with long brown standing hairs; petiolar spine densely with long brown standing hairs; gaster with dense pubescence mixed with dense long brown standing hairs; median point of anterior clypeal margin with a long standing hairs; legs with dense standing hairs. Body entirely black; legs entirely black, except trochanters which are paler than elsewhere.

Etymology. The specific epithet “ longipilosa ” is a Latin word meaning “with long hairs” and refers to the hairs on body compared with the very short or missing standing hairs in other species of the Polyrhachis flavicornis species group.

Habitat. The new species was collected from the canopy at about 25 m above the ground, while P. constructor , P. varicolor , and P. flaviconis were found on shrub trees at 1.59–5 m above the ground and nested on the underside of plant leaves or between leaves (Noon-anant et al. 2008, Noon-anant et al. 2009).

Distribution. Thailand (Kanchanaburi province, Fig. 10 A ).

Remarks. Polyrhachis longipilosa sp. nov. is similar to P. constructor . However, P. longipilosa is easily distinguished from the latter by the following worker characteristics: 1) hairs on antennal scape longer than maximum width of antennal scape (shorter or almost as long as maximum width of antennal scape in P. constructor ); 2) petiolar spine with long standing hairs (without standing hairs in P. constructor ); 3) hairs on first gastral tergite almost as long as maximum diameter of eye (distinctly short than maximum diameter of eye in P. constructor ); 4) head and mesosoma with stronger sculpturing (weaker sculpturing in P. constructor ; see figs 1A–C and 6 for comparison); 5) striation on pronotum well-defined (ill-defined in P. constructor ; see figs 1B and 7C for comparison).

Figures

FIGURE 7. Polyrhachis longipilosa sp. nov. (holotype worker, THNHM-I-26206).A, Body in profile view; B, head in full-face view; C, body in dorsal view.

FIGURE 10. Distribution map of Polyrhachis flavicornis species group. A) P. constructor and P. longipilosa sp. nov. B) P. flavicornis and P. varicolor.