Pheidole loki, Fischer & Fisher, 2013

FISCHER, G. & FISHER, B. L., 2013, A revision of Pheidole Westwood (Hymenoptera: Formicidae) in the islands of the Southwest Indian Ocean and designation of a neotype for the invasive Pheidole megacephala, Zootaxa 3683 (4), pp. 301-356 : 331

Pheidole loki sp. n.

( Figs. 20A–F )

Holotype: (minor worker), MAYOTTE, Mt. Benara , 12.8667 S, 45.1833 E, 630 m, forest, sifted leaf litter, collection code RJ1955, 23.ii.1999 (R. Jocque & G. DeSmet) ( CASC: CASENT0059150 ).

Paratype: (1 minor worker), MAYOTTE, Mt. Combani , 12.8 S, 45.1833 E, 470 m, forest, sifted leaf litter, collection code RJ1959, 22.ii.1999 (R. Jocque & G. DeSmet) ( CASC: CASENT0059114 ) .

Diagnosis (minor workers only): Relatively small species (WL 0.62–0.65 mm) with moderately short scapes and legs (SI 117–122, FI 117–120), promesonotal process absent or inconspicuous, postpetiolar ventral process absent, postpetiole significantly longer than high (LPpI 147) and longer than wide (DPpI 86), face posteriorly superficially punctate to smooth, sculpture on mesosoma reduced and mostly superficially punctate to smooth, standing hairs subdecumbent to suberect and relatively rare.

Description of minor workers: Measurements (holotype): HW 0.46, HL 0.52, SL 0.54, MDL 0.31, EL 0.10, WL 0.65, PNH 0.25, PNW 0.31, MNH 0.40, PDH 0.20, PTL 0.25, PPL 0.14, PTH 0.13, PPH 0.10, PTW 0.07, PPW 0.12, PSL 0.06, MFL 0.55, MTL 0.42, CI 88, SI 117, MDI 67, EI 22, FI 120, PSLI 13, LPpI 147, DPpI 86, PpWI 171, PpLI 56, PpHI 76.

Measurements (n=1): HW 0.46, HL 0.51, SL 0.56, MDL 0.30, EL 0.10, WL 0.62, PNH 0.24, PNW 0.31, MNH 0.39, PDH 0.19, PTL 0.22, PPL 0.14, PTH 0.12, PPH 0.10, PTW 0.07, PPW 0.12, PSL 0.06, MFL 0.54, MTL 0.42, CI 90, SI 122, MDI 65, EI 21, FI 117, PSLI 13, LPpI 147, DPpI 86, PpWI 171, PpLI 64, PpHI 79.

Head subrectangular, slightly longer than wide (CI 88–90), sides convex, posterior head margin weakly concave medially, occipital carina invisible in full-face view. Mandibles relatively short (MDI 65–67), longitudinally striate. Clypeus smooth, without median and lateral carinae. Face punctate to weakly punctate, grading to superficially sculptured or smooth near posterior head margin, punctures between antennal sockets and eyes may be overlain with faint malar carinae. Scapes moderately short (SI 117–122), when laid back surpassing posterior head margin by slightly more than length of tenth funicular segment, pilosity decumbent to suberect. Promesonotal outline in profile strongly convex, with a rounded angle between pronotal dorsum and long, relatively steep, posterior declivity. Metanotal groove shallow, with long weakly to superficially developed crossribs, interspaces between dorsal cross-ribs smooth and shiny, propodeum slightly shorter than high, in profile weakly convex. Promesonotum dorsally superficially punctate to smooth, with few faint to inconspicuous transverse rugulae, remainder of mesosoma weakly to superficially punctate with small smooth spot on anterior katepisternum. Propodeal spines short-acute, much shorter than distance between their bases (PSLI 13). Metafemur moderately short (FI 117–120), metatibia pilosity decumbent with longer suberect hairs on outer edge. Postpetiole almost 1.5 times longer than high (LPpI 147) and in dorsal view longer than wide (DPpI 86), petiole and postpetiole smooth. Gaster smooth and shiny. Standing hairs on mesosoma and metasoma moderately scarce, acute, slender, and moderately long, some bent anteriorly, subdecumbent to suberect. Shorter pilosity decumbent and slightly more abundant. Color dark orange to brown, mandibles and legs lighter.

Discussion: The two specimens of Pheidole loki were collected in forest leaf litter in 470 and 630 m elevation on Mt. Combani and Mt. Benara, Mayotte, where it occurs in sympatry with P. jonas . Majors for this possibly rare species could not be found and thus remain undescribed. Pheidole loki is most probably closely allied to P. jonas and P. vulcan and characterized by reduced sculpture and an intermediate amount of standing hairs, compared to these two species. Overall it resembles P. jonas more than P. vulcan , at least in habitus, morphometric measurements, and promesonotum and postpetiole shape. The minor workers of P. jonas , however, display a more strongly punctate sculpture, less abundant and less flexuous standing hairs, and on average slightly shorter scapes (SI mean 109 versus SI mean 120) than P. loki , the postpetiole on average as long as wide (DpPI 88–109) versus longer than wide (DPpI 86) in P. loki . With all these easily visible differences between the minor workers of the two species, especially their very distinct pilosity patterns, the chance that P. loki is a morphologically aberrant conspecific of P. jonas is probably small.

Etymology: This species is named after Loki, the god of mischief and chaos in Norse mythology, who is sometimes also referred to as a trickster or a shape shifter. The name is a noun in apposition and thus invariable.

Figures

FIGURE 20 Pheidole loki sp. n., full-face view (A), profile (B), and dorsal view (C) of holotype minor worker (CASENT0059150).