Apetasimus abstrusus Ewing

Ewing, Curtis, 2006, Revision of the endemic Hawaiian sap beetle genus Apetasimus Sharp 1908 (Coleoptera: Nitidulidae), Zootaxa 1385, pp. 1-30 : 18-19

Apetasimus abstrusus Ewing sp. nov.

Diagnosis

Distinguishable from brachypterous Eupetinus and Gonioryctus by reduced eyes and tarsal lobes, more rounded temples and convex pronotum. Closely resembles A. conditus from Molokai but separated by shallow pronotal punctures, appearing irregular with intervals granular and prosternal process meeting postcoxal sclerites at 45° angle vs. 60° angle for A. ganeademus . ( Fig. 4 D).

Description

Size: Length 4.7mm, Width 2.1mm

Color: head and elytra orange-red, remainder pale yellow

Head: Transverse ( Fig. 4 B), 0.72mm L, 0.96mm W, L/W ratio 0.75. Punctation shallow, dense, adjacent punctures often contiguous, interval microsculpture on clypeus granular, elsewhere linear. Eye reduced, length 0.07mm, facets 6, anterior medial margin convergent. Temple distinct, forming obtuse angle with convex postgena. Antennomeres 1–4 elongate, 5 quadrate, 6–8 transverse.

Prothorax: Pronotum transverse, 1.09mm L, 1.74 W, L/W ratio 0.63 ( Fig. 4 E). Lateral margin weakly explanate in anterior 1/2, with even increase in width to strongly explanate posterior angle. Lateral margin broadly rounded, widest behind midpoint, slightly sinuate before hind angle, hind angle definite, nearly at a right angle. Anterior margin distinctly narrower than posterior margin, anterior/posterior width ratio 0.62. Distinctly emarginate anteriorly, angles rounded. Posterior margin shallowly bisinuate. Bead definite from inside anterior angle to posterior angle, obsolete at posterior margin of angle, defined by fine line posterio-medially. Punctation of disc shallow, dense, becoming less definite laterally, indistinct at margin and appearing roughened, intervals granular. Prosternal process short, narrow between coxae, expanded apically ( Fig. 4 C), strongly recurved dorsad behind coxae, meeting mesosternum at approximately 45° angle, apex fimbriate ( Fig. 4 C).

Elytra: 1.74mm L, 1.21mm W, L/W ratio 1.44 ( Fig. 4 A). Surface uneven, striae shallow, slightly irregular, striae wider than interstices. Striae consisting of dense, irregular punctures, appearing unevenly granular, interstices crossed by numerous irregular lines. Lateral margin evenly curved, abruptly and widely explanate behind humeri, narrowed evenly to posterior angle. Posterior margin shallowly bisinuate.

Legs: Lobes of pro- and mesotarsomeres 1 and 2 obsolete, 3 extended 1/2 length of tarsomere 4. Metatarsomeres 1–3 with lobes obsolete ( Fig. 4 F).

Abdomen: Male; surface of tergite 5, 6, and pygidium with granular microsculpture, punctures distinct medially, dense and irregular laterally. Female; pygidium with punctation large anteromedially, progressively finer and less distinct toward apex, shallow medial depression at posterior margin appearing emarginate when viewed from angle. Apex of pygidium rounded, fimbria short ( Fig. 2 F). Apex of sternite 7 broadly rounded, fimbria short ( Fig. 2 G).

Holotype Ψ, labeled: "Oahu, Waianae Mts., Mt. Kaala NAR, 18–V–1991, el. 1,210m., Sifting tree fern litter beside road, J. K. Liebherr coll." (CUIC).

Etymology: (L.) abstrusus ; hidden, concealed.

Distribution: Known from type locality.

Habits: Apparently rare, although the holotype was collected in tree fern litter it is possible that it is common in a different habitat. Mt. Kaala is one of the most intensively collected native dominated forest habitats in Hawaii, and other species of endemic nitidulid (i.e. Eupetinus ) have been repeatedly collected in litter there.

Figures

FIGURE 2. Apetasimus involucer. A. Aedeagus and sac (dorso-lateral view); B. Male perisac (ventral view); C. Aedeagus (ventral view); D. Aedeagus (lateral view); E. Elytron, setal tufts indicated; F. Female pygidium. G. Female sternite 7. H. Male pygidium. I. Male sternite 7. J. Left protarsi (dorsal view). K. Pronotum, dashed line indicates explanate margin; L. Head. M. Tegmen (ventral view); N. Male segment 8 (ventral view). ae anterior excavation, aed aedeagus, di dorsal incision, fl flagellum, lf lateral fold, lp lip of anterior excavation, ma retractor muscle attachment, mt median triangle, pe posterior excavation, s 8 sternite 8, sd sperm duct, hl head length, sp sclerites-primary, t 8 tergite 8, vi ventral incision, vh ventral hook.

FIGURE 4. Apetasimus abstrusus sp. nov. A. Elytron, dashed line indicates explanate margin; B. Head; C. Prosternum (ventral view); D. Prosternum (lateral view); E. Pronotum, dashed lines indicate explanate margins; F. Left protarsi (dorsal view). Apetasimus ganeademus sp. nov. G. Prosternum (lateral view); H. Pronotum; I. Left elytron, dashed line indicates boundary of explanate margin; J. Female pygidium. Apetasimus conditus sp. nov. K. Elytron, dashed line delimits explanate margin; L. Pronotum, dashed lines delimit explanate margins; M. Left mesotarsi (dorsal view). c clypeus, mai median apical impression, el elytral length, v vertex.