Prenolepis lakekamu, Williams & Lapolla, 2018

Williams, Jason L. & Lapolla, John S., 2018, Two new Prenolepis species (Hymenoptera: Formicidae) from Indomalaya and Australasia, with a redescription of P. dugasi from Vietnam, Zootaxa 4441 (1), pp. 171-180 : 176-178

Prenolepis lakekamu , sp. nov.

Figs. 10–12 (worker)

Holotype worker, PNG: Gulf Province, Ivimka Res. Station, Lakekamu Basin ; 7°44'S, 146°30'E; elev. 120 m ; 24.xi.1999; S.L. Heydon (USNMENT01126705) (USNM). 1 paratype worker, same locality as holotype (USNMENT01126706) ( USNM) .

Worker diagnosis: Gracile mesosoma with an obtuse angle forming where the pronotum and mesonotum meet, and a sharp decline in the mesonotum just posterior to the pronotum, followed by an upward deflection that flattens out anterior to the metanotum ( Fig 2 ). The dorsal face of the propodeum is distinctly flat and much longer than the rounded posterior face, giving the propodeum an elongate profile. The petiole is low in profile and has a distinct shape, with a flattened scale and a right angle formed at its anterodorsal point, and a weakly sinuate anteroventral outline ( Fig 5 ).

Compare with: P. jacobsoni , P. jerdoni , P. subopaca

WORKER. Measurements (n=2): CMC: 14; EL: 0.15–0.17; HL: 0.58; HW: 0.50–0.52; MMC: 1; PMC: 1–2; PrMC: 1–2; SL: 0.68–0.69; TL: 2.38–2.45 WL: 0.83–0.87; CI: 87–88; REL: 26–28; REL2: 30–32; SI: 133–135.

Yellow mesosoma, legs, and antennae with medium to dark brown head and gaster; entire cuticle smooth and shiny; very long, erect macrosetae on head, mesosoma, and gaster; abundant suberect to erect setae on scapes and legs; head slightly longer than broad and round in shape with indistinct posterolateral corners and convex posterior margin; no ocelli present; compound eyes moderately large and convex, slightly surpassing lateral margins of head in full-face view; torulae do not touch posterior border of clypeus; clypeus strongly medially convex with prominent anterolateral lobes ( Fig 2 ); mandibles with 5 teeth on masticatory margin; ectal surface of mandibles smooth and shiny; in profile view, mesosoma is gracile; pronotum is mostly flat and inclines posteriorly; an obtuse angle forms where pronotum and mesonotum meet, and mesonotum sharply declines with an upward deflection posteriorly that flattens just anterior to metanotum; propodeum is posteriorly rounded; dorsal face of propodeum is flat and longer than posterior face; petiole scale low in profile; anterodorsal surface of petiole forms a right angle and does not rise high above as an apex, but instead is flat anteriorly and gradually declines at about a 20 degree angle posteriorly; ventral surface of petiole is entirely rounded with a weakly sinuate anteroventral outline ( Fig 5 ).

Etymology: The specific epithet is named after the Lakekamu Basin, where the type series was collected.

Notes: This species most strongly resembles the three species found mostly across maritime Indomalaya ( P. jacobsoni , P. jerdoni , and P. subopaca ) but is instead known only from Papua New Guinea, east of Wallace’s Line. It is also most readily distinguished morphologically from these other three species by its distinct color patternhaving a yellow mesosoma and medium to dark brown head and gaster—and its flattened, more elongate propodeum. The above three species and P. lakekamu each have a petiole shape distinct among them and unlike those of all other Prenolepis species. The petiole of P. lakekamu has a weakly sinuate anteroventral outline that most strongly resembles what is seen in P. jacobsoni , but P. lakekamu lacks the diagnostic prominent anteroventral process seen in P. jacobsoni and instead has a gently rounded ventral surface. The color pattern seen in P. lakekamu is similar to that of P. melanogaster , but P. melanogaster is much larger (TL> 4.5 mm), has a head that is slightly broader than long with eyes spaced far apart, and far more numerous erect macrosetae all across the head, mesosoma, and gaster.

Figures

FIGURES 10–12. Prenolepis lakekamu holotype worker USNMENT01126705. Lateral, full-face, and dorsal view of the body.

FIGURES 1–3. Illustrations of head shapes in full-face view for all three species. 1, P. dugasi; 2, P. lakekamu; 3, P. nepalensis.

FIGURES 4–6. Illustrations of mesosoma shapes in profile view for all three species. 4, P. dugasi; 5, P. lakekamu; 6, P. nepalensis.