Akidomorychus, Lawrence, John F., Slipinski, Adam, Jäger, Olaf & Pütz, Andreas, 2013

Lawrence, John F., Slipinski, Adam, Jäger, Olaf & Pütz, Andreas, 2013, The Australian Byrrhinae (Coleoptera: Byrrhidae) with descriptions of new genera and species, Zootaxa 3745 (3), pp. 301-329 : 315-318

Akidomorychus gen. n. (figs 7, 11a, 12b)

Type species: Pedilophorus polychromus Lea 1920 .

Diagnosis. Species of Akidomorychus differ from those of Notolioon, Nothochaetes and Idiothrix in having the metanepisternum free, completely exposed, widest anteriorly and narrowing posteriorly ( Fig. 7 A) and from the last and those of Brachybyrrhulus and Pseudomorychus in having the protibia distinctly expanded at middle and lined with equally spaced, spine-like setae ( Fig. 7 D) and in lacking curved postcoxal lines on the metaventrite ( Fig. 7 A). Males differ from those of all other byrrhines in having the parameres diverging and their mesal edges more or less excavated ( Figs 7 B, 12B), while the females are distinguished from those of other genera in having heavily sclerotized, curved and spur-like gonostyli ( Fig. 7 C).

Description. Length 2.0–4.0 mm. Body short and broad (body length/elytral width = 1.28–1.43); lateral outline more or less continuous. Color of head and pronotum black to metallic reddish-violet; elytra black to dark metallic green; ventral surfaces reddish-brown to black; legs reddish-brown; antennae and palps yellowish-brown to reddish-brown. Dorsal vestiture consisting of long but fine, erect, dark hairs and shorter decumbent to suberect, yellow, white or reddish hairs, sometimes unevenly distributed and forming patches or transverse bands; ventral surfaces with moderately long, decumbent hairs.

Head almost as long as width behind eyes, strongly declined and deeply inserted into prothorax, but with eyes at least partly visible; occipital region with short median endocarina, transverse occipital ridge absent. Eyes relatively small, not protuberant, located anteriorly. Frontoclypeal suture absent; frontoclypeal region weakly declined without distinct frontal ridge; antennal insertions exposed or barely concealed from above; subantennal grooves weak, extending to edges of eyes. Labrum relatively large and well sclerotized, with distinct transverse groove at base; apex subtruncate. Antennae about as long as or slightly shorter than head width behind eyes, 11- segmented, with 4- or 5-segmented club; scape about twice as long as wide, pedicel a third to half as long, distinctly narrower and 1.75 times as long as wide; antennomere 3 1.5–1.75 times as long as pedicel and 2.25–3.2 times as long as wide; antennomeres 4 and 5 slightly longer than wide and 6 and 7 about as long as wide, but 7 somewhat widened and may or may not be considered part of antennal club; 8–11 forming distinct club, the first four transverse and the last about 1.33 times as long as wide. Mandible broad, subtriangular and obliquely tridentate, dorsal surface with distinct ridge fitting against sides of labrum; mesal surface of mandibular base without mola but with basal brush of hairs. Maxilla with short, densely setose galea and lacinia; apical maxillary and labial palpomeres more or less fusiform. Subgenal ridges present but usually weak. Gular sutures well separated; gula transverse; corporotentorium broad, straight; cervical sclerites well-developed.

Pronotum 0.38–0.55 times as long as wide, widest at base; anterior edge broadly rounded or subtruncate; sides straight or somewhat sinuate and gradually narrowing anteriorly; anterior angles small and acute; lateral carinae complete but very narrow not visible for their entire lengths from above; posterior angles produced and acute; posterior edge somewhat angulate, unmargined, with distinct posterior accessory ridge beneath; disc moderately convex, with steep sides anterolaterally. Prosternum in front of coxae about 0.33–0.5 times as long as mid length of coxal cavity, slightly convex, with paired lateral antennal grooves and a concave head rest above. Prosternal process complete, parallel-sided or slightly narrowing posteriorly and truncate or broadly rounded at apex. Procoxa more or less cylindrical, with well-developed exposed trochantin, without or with small coxal plate; procoxal cavities strongly transverse, broadly open externally and internally. Notosternal sutures complete and anteriorly open. Hypomeron concave posteriorly, forming with epipleuron a large impression for housing legs and antennae.

Scutellar shield about 0.1 times as wide as base of one elytron, slightly elongate and apically subacute. Elytra about 0.91–0.96 times as long as wide and 1.88–2.95 times as long as pronotum; sides gradually curved or slightly sinuate, widest at anterior third or middle, narrowing posteriorly, with distinct, angulate humeri; disc strongly, evenly convex; elytral apex with or without ventral interlocking tongue; epipleuron relatively narrow, anteriorly concave forming posterior part of crural impression, narrowing posteriorly and ending at posterior edge of metaventrite.

Mesoventrite strongly transverse, separated by complete sutures from mesanepisterna, which are very widely separated; anterior edge on different plane than metaventrite, with a pair of large, strongly declined to vertical procoxal rests continued onto mesanepisterna and with moderately deep mesoventral cavity; discrimen usually present just behind cavity. Mesoventral process short, broad and apically emarginate forming a pair of apicolateral condyles. Mesocoxae slightly transverse, with short coxal plates and exposed trochantins. Mesocoxal cavities separated by about 1.6 times shortest diameter of coxal cavity, partly closed laterally by mesepimera and mesanepisterna, which are more or less fused together.

Metaventrite moderately short, its shortest length 1.1–1.2 times shortest diameter of mesocoxal cavity; without postcoxal lines, but with weak crural impressions in comatus and a transverse postcoxal line joining two coxal cavities across base of metaventral process in polychromus and raucus ; discrimen short or absent; anterior metaventral process with pair of anterolateral cavities for receiving mesoventral condyles; exposed portion of metanepisternum about 3.5 times as long as wide, widest near anterior end and gradually narrowing posteriorly; metepimeron not or slightly exposed. Metacoxae about 0.25 times as long as wide at base, not projecting, separated by less than 0.1 times basal width, extending laterally to meet elytra, with well-developed, complete coxal plates widest at about mesal third. Metendosternite with short to very short, broad stalk, long, narrow, diverging lateral arms and no laminae or anterior process. Hind wings absent.

Legs relatively short; femora and tibiae subequal in length; femora at least slightly grooved for reception of tibiae; protibiae distinctly expanded, widest at middle, with evenly curved outer edge and distinct groove for reception of tarsus; meso- and metatibiae less expanded and widest at about apical fourth; outer edges of all tibiae well separated spine-like setae mixed with long, fine hairs. Tarsi 5-5-5, tarsomere 4 reduced, tarsomere 3 bearing a long, hyaline, setose ventral process longer than body of tarsomere; pretarsal claws simple.

Abdomen about 0.65–0.75 times as long as wide at base with five ventrites, the first three of which are connate; first ventrite with anterolateral corners slightly impressed and with short, broad, intercoxal process, truncate at apex; ventrite 5 about as long as or slightly longer than 3 and 4 combined. Abdominal tergites lightly sclerotized or membranous. Functional spiracles on abdominal segments I–VIII. Anterior edge of sternite VIII in male with short, broad, rounded anterior projection. Sternite IX in male slightly elongate, truncate at base (anteriorly) and broadly rounded at apex (posteriorly); tergite IX transverse and undivided, broadly emarginate at apex; tergite X (proctiger)

partly fused to tergite IX, broadly rounded at apex. Aedeagus with phallobase symmetrical, about as long as wide, with narrowly rounded lobe at base; parameres diverging, broadest at base, gradually narrowed and rounded at apex, with inner edge of each more or less excavated; penis widest at base and gradually narrowed apically, narrowly rounded and cleft at apex, with short basal struts. Anterior edge of sternite VIII in female biemarginate or with short angulate or truncate anterior process (spiculum ventrale), posterior edge broadly rounded; tergite VIII transverse and undivided; tergite IX consisting of paired laterotergites (paraprocts) connected at midline by a slender, lightly sclerotised strip. Female proctiger about as long as wide at base, which is completely fused to tergite IX, broadly rounded at apex. Female proctiger about 0.75 times as long as wide. Ovipositor slightly longer to 1.5 times as long as wide; paraprocts about 0.6–0.8 times as long as gonocoxites, each of which has an elongate, laterally compressed and well sclerotized distal lobe with an apical, heavily sclerotized, outwardly curved, spurlike gonostylus about 0.33 times as long and broadly rounded apically in lateral view.

Etymology. Akis, akidos (Greek, f), barb or point, and the Holarctic genus Morychus . The name refers to the unique form of the gonostyli.

Included species. A. comatus (Oke 1932: 158) comb. n., A. polychromus (Lea 1920: 287) comb. n., A. raucus (Blackburn 1891: 133) comb. n., A. venustus (Wilson 1921: 33) comb. n.

Distribution. The genus is widely distributed in southeastern Australia, from Victoria and South Australia to northern New South Wales, but it has not yet been recorded from Tasmania or Queensland. The species limits are not clear in this genus and at least one, if not two, of the above species may be synonyms. This problem will be addressed in a species-level revision in preparation.

Figures

FIGURE 7. Byrrhinae: Akidomorychus spp.: A – F, A. polychromus (Lea): A, right side of pterothorax, with right mesocoxa and both metacoxae removed; B, aedeagus, ventral; C, ovipositor, ventral, showing hook-like styli; D, fore leg; E, antenna; F, habitus, dorsal, length = 2.6 mm. G, A. raucus (Blackburn), habitus, dorsal, length = 3.2 mm