Aphilon Sharp, 1876

Leschen, Richard A. B., Reid, Chris A. M. & Nadein, Konstantin S., 2020, Generic Review of New Zealand Chrysomelinae (Coleoptera: Chrysomelidae), Zootaxa 4740 (1), pp. 1-66 : 7-9

Aphilon Sharp, 1876

( Figs 1A, B, E , 13A)

Aphilon Sharp, 1876:100 . Type species: Aphilon enigma Sharp, 1876 , by monotypy.

Diagnosis. Body length 1.3–3.2 mm; round and strongly convex; unicoloured, sometimes with a green or blue metallic sheen. Antennae clavate. Procoxal cavities externally open. Hindwings absent. Anterior edge of metaventrite curved or rounded; metaventral lines distal forming a broad surface behind the mesocoxae. First abdominal ventrite with subcoxal lines parallel and not extending to middle of ventrite.

Description. Length 1.3–3.20 mm. Body rounded, strongly convex, globose; colouration dark brown to black and sometimes with a green or blue metallic sheen.

Head not forming a short muzzle with genae extending a short distance beyond level of antennal and maxillary insertions, scarcely visible in dorsal view with mouthparts directed ventrally, vertex or frons wide, nearly flat to feebly convex; postantennal calli weakly developed, pale areas present. Eyes small, elliptical, and convex, coarsely facetted and consisting of about 20 to 30 ommatidia; inner margin of eye without a small seta. Antennae relatively short, not reaching far beyond the hind margin of the pronotum; antennal club well developed (antennomeres 7–11); insertions contacting or not the margin of eye (distance between insertion and margin of eye is less than diameter of insertion), with distance between insertions about 3 times length of the scape. Clypeus triangulate or semicircular, frontoclypeal suture present, frons without postclypeal lines. Labrum somewhat rectangular and transverse with curved sides, anterior margin emarginated, surface with 3 setae per side, anterior margin at middle lacking distinct setal fringe, tormae long and thin, over 3 times longer than labral plate. Mandible lacking serrate terebral edge. Maxillary palpus relatively long, palpomere 1 longer than wide, palpomere 2 transverse and shorter than wide, palpomere 3 about 2 times longer than wide, greater in length than palpomere 2, conical to weakly acute. Labium with relatively narrow ligula, narrower than lengths of palpomeres 1 and 2 combined, apex undivided, palpal insertions separated by at least the width of the basal palpomere, palpi relatively short, palpomere 1 as wide as long, palpomere 2 slightly longer than wide, palpomere 2 times longer than wide with narrowed and truncated apex. Mentum rectangular and transverse 3 to 5 times wider than long to almost quadrate; width of mentum equal to, or shorter than the length of labial palpomere 1. Intermaxillary process delimited behind by a ridge and not extending anteriorly far beyond maxillary insertions, bead present or absent.

Pronotum transverse, very convex, with a bead along anterior and lateral margins, its base as wide as or just slightly shorter than the base of elytra; anterior margin straight in dorsal view, lateral margins rounded and converging anteriorly, anterior angles not projecting and rounded to subacute; sides distinctly converging anteriad and straight or weakly curved, posterior margin weakly convex; posterior angles acute; disc convex without sublateral groove, trichobothria absent, coarse and dense punctures at middle of posterior margin present or absent; lateral carinae complete. Prosternum not vaulted at middle (weakly vaulted in one undescribed species), without transverse notches in front of coxal cavities; prosternal lines present and parallel and extending forward reaching anterior edge of sternite, or divergent anteriorly, or absent; prosternal process broad, short and extending a short distance behind procoxae, expanded laterally behind coxae but not contacting the hypomeral process; posterior weakly emarginate, procoxal cavities externally open. Notopleural suture distinct. Scutellary shield small, triangular with an acute or rounded apex or not visible between elytral bases. Elytra short, convex, humeral calli and midbasal striae absent; surface smooth to punctate punctures weakly impressed confused to striate; epipleura wide and well developed, visible in lateral view, apex without ctenidium. Hind wings absent. Mesoventrite mostly hidden in ventral view, posterior portion between mesocoxae visible as a narrow strip; mesal part of mesoventrite with vertical surface confluent with prepectus. Meso- and metacoxae widely separated. Metaventrite shorter or longer than abdominal ventrite I at midline, mesocoxal process very short and broad with a curved or rounded anterior margin, metaventral lines not parallel, discrimen absent, transverse metaventral (metakatepisternal) suture present and crossing the midline or absent. Metendosternite lacking stalk and laminae, widely spaced lateral arms with subapical anterior tendons. Legs with only metatibiae flattened in cross section, not clubbed and gradually widened distally, apically setose; tarsomeres usually 5-5-5 (some smaller species may be 4-4-4) and variable, T1 2–3 times longer than T2, about 2 times longer than wide, T2 transverse and wider than long, T3 about as wide as long and deeply incised (bilobed), tarsomere 4 minute or absent, T5 longer than T2+T3, claws simple, tarsomere 1 on all or anterior and middle legs of male greatly enlarged.

Abdominal ventrite 1 long, but shorter than ventrites 1–5 combined, with a broad metacoxal process that is wider than long and with a straight apical margin, ventrites 2–4 equal in length and much shorter than ventrite 1, ventrite 5 longer than ventrites 3 and 4 combined with rounded posterior margin; first abdominal ventrite with subcoxal lines parallel to coxal cavity not extending to middle of ventrite. Aedeagus curved in lateral view and rounded in cross section; apex in dorsal view subrounded to subacute or apiculate; flagellum present or absent. Ovipositor with coxites elongate, more than 3 times longer than wide and lacking a stylus. Spermatheca curved and C-shaped, collum present, with spermathecal duct inserted onto base, spermathecal gland absent.

Comments. This endemic genus contains 10 species with the exclusion of one species transferred to Maurodus ( A. impressus Broun, 1914 ) and two species transferred to Caccomolpus (see below). All live at ground level and are flightless having relatively short metaventra and lack hindwings. Aphilon species are similar to some Caccomolpus , but most species can be distinguished by their small size and almost completely round and highly convex bodies, though a break in contour is present in A. latulum Broun , but, most importantly, all have parallel subcoxal lines on abdominal ventrite 1 (including larger species like A. monstrosum Broun, 1886 ). Most Aphilon have distinctly clavate antennae, but this character is also present in Nanomela and Zeaphilon . The round and highly convex body shape of Aphilon distinguishes this genus from members of Maurodus , Zeaphilon , and Nanomela . Some species have been collected at night feeding on mosses and liverworts ( Kuschel 1990), otherwise they can be collected by sifting leaf litter.

We are unable to provide a key to the species as the exact number of valid species is undetermined and the status of the described species must be confirmed by further revision of both Aphilon and Caccomolpus . However the type material is reviewed below, with lectotype designations where appropriate. The unusual larva with fused terga noted by Reid & Leschen (2003) needs full description.

Included species. Aphilon convexum Broun, 1893 , A. enigma Sharp, 1876 , A. latulum Broun, 1893 , A. minutum Broun, 1880 , A. monstrosum Broun, 1886 , A. praestans Broun, 1893 , A. punctatum Broun, 1880 , A. scutellare Broun, 1893 , A. sobrinum Broun, 1886 , A. sternalis Broun, 1921 .

Distribution. North Island, South Island. Most of the specimens in the NZAC are from the North Island; however, there is a small number of specimens of a new species from Fiordland.

Figures

FIGURES 1A–F. Habitus and structures of Aphilon and Caccomolpus; A, Aphilon sp., dorsal view, length 2.2 mm; B, Aphilon sp., lateral view; C, Caccomolpus sp., dorsal view, length 2.7 mm; C, Caccomolpus sp., dorsal view; D, Caccomolpus sp., lateral view; E., Aphilon sp., front of head; F, Caccomolpus sp., abdominal ventrites.