Antecessorirhyparus samoaensis Skelley & Minkina, 2025

Antecessorirhyparus samoaensis Skelley & Minkina , new species

Figures 5–9 View FIGURES 5–9

Diagnosis. Antecessorirhyparus samoaensis is distinguished by its small, parallel-sided body, length 3.4 mm ( Figs. 5–7 View FIGURES 5–9 ). Pronotal paramedian costae constricted on anterior third; anterior and posterior parts of paramedian costae parallel with each other ( Fig. 8 View FIGURES 5–9 ); median intercostal area with large punctures on most of surface and distinct lateral pits at basal third; lateral intercostal areas convex and shiny in posterior half, with only minute punctures; lateral margin almost straight, lobes indistinct. Elytron with length two times pronotal length; discomedian costa with a caudal tuft of setae short ( Fig. 9 View FIGURES 5–9 ); intercostal areas convex, almost same height as costae; and caudal bulb not interrupting juxtasutural costa, which attains elytral apex.

Description. Holotype female. Body length 3.4 mm, width 1.2 mm. Elongate-oval, flattened, dark brown, glossy, appearing almost glabrous, partly clothed with fine, pale yellow setae on head and all longitudinal costae on pronotum and elytra. Head. Surface glossy, transversely sub-hexagonal. Clypeus trapezoidal in outline, anteriorly truncate, anterior margin upturned with obtuse, distinct tooth on each side of medial third, lateral thirds sinuous. Genae distinctly excavated anterior of eyes. Clypeocentral disc distinctly convex with two short and wide costae; peridiscal impression visible on basal half. Frons with four frontodiscal costate. Head covered by very irregularly spaced, fine to moderate punctures; all punctures with short, pale yellow setae. Pronotum. Surface glossy, widest in middle, with paramedian, discolateral, posthumeral, and submarginal costae evident. Costae on each side with very small punctures bearing very small setae. Paramedian costae constricted at anterior third, anterior and posterior parts parallel with each other. Discomedian costa distinctly interrupted by fovea on anterior third. Submarginal costa complete. Costal intervals 1–3 with large puncture near anterior margin, convex and costate in posterior half; interval 1 (median) between paramedian pronotal costae with numerous large punctures and distinct pores at basal third; interval between submarginal costa and lateral margin convex medially only. Lateral margin nearly straight, with indistinct anterior and intermediate lobes. Elytra. Surface glossy; each elytron with nine elevated costae and nine striae. Costae on each side with a row of very small punctures bearing very short setae. Odd numbered costae slightly higher than even numbered costae, corresponding to juxtasutural, discomedian, discolateral, and posthumeral costae. Elytral humerus at base of posthumeral costa bearing short macrosetae. Striae with large punctures, which weakly indents costal margins. Postdiscal bulbs at caudal apex of discomedian and discolateral moderately developed; apex of discomedian costa with short setal tuft. Caudal bulbs large, laterally truncate, not interrupting juxtasutural costa, which attains elytral apex. Caudal trichomes small. Venter. Surface weakly glossy. Metaventrite flattened, in the middle with distinct deep longitudinal median impression in posterior half, impression narrowing anteriorly; disc on either side with punctation large and regularly spaced, decreasing in size anteriorly and laterally, all punctures bearing short setae.Abdominal ventrites 2–5 with transverse anterior groove in which are large deep large punctures; laterally ventrites with 1–2 large punctures in shallow depression, rest of surface with scattered fine punctures bearing short setae. Abdominal ventrite 5 (last) with two large medial punctures, weakly longer in middle, with rather shallow furrows laterally. Pygidium with triangular fovea on each side of median carina. Legs. All femora weakly glossy, with moderately deep, distinct punctures; all punctures bearing very short setae. Mesotibia and metatibia weakly widened to narrow truncate apex. Mesotarsus and metatarsus with first tarsomere elongate, as long as next three tarsomeres combined.

Distribution. Samoa.

Material examined. The holotype female deposited at NZAC: “ Aleisa Cave 1800’ / Upolu, W. Samoa / 2.IV.69 A.K. Walker / cave entrance // Damp leaf litter / under large / tree roots // Aleisa Cave / #183 // [yellow paper] N.Z.Arthropod / Collection, NZAC / Private Bag 92170 / AUCKLAND / New Zealand // [red paper] HOLOTYPE ♀ / Antecessorirhyparus / samoaensis Skelley / & Minkina 2025 ” .

Etymology. Toponymic. Named for the country where it occurs.

Comments. Antecessorirhyparus samoaensis in western Polynesia, is presently the only known species of Rhyparini that is endemic and suspected to be native to Samoa. Two other species, R. helophoroides and R. rugatus , are widespread and suspected to have recently arrived in Samoa (see comments under those species).