Australonotha Yoshida & Leschen, 2020

Yoshida, Takahiro & Leschen, Richard A. B., 2020, A new genus of Pharaxonothinae from Australia (Coleoptera: Erotylidae), Zootaxa 4838 (2), pp. 273-282 : 274-275

Australonotha Yoshida & Leschen , gen. nov.

Type species. Australonotha monteithi Yoshida & Leschen , sp. nov., by present designation.

Diagnosis. Specimens of Australonotha are similar to members of Languriinae by having the prothorax longer than wide and a transverse depression at the base of the pronotum, but differ from them by having a transverse line on the vertex of the head and lacking lobed tarsomeres. Similar-looking Erotylinae , especially dacnines and other erotylids that also lack lobed tarsomeres, as well as Cryptophilinae (e.g., Brachypterosa Zablotny & Leschen, 1996 ), also lack the transverse line on the vertex of the head. Among the more basal erotylids, only the xenosceline genus Zavaljus Reitter and Australonotha do not have a strongly reduced tarsomere 4. Australonotha can be distinguished from all other members of Pharaxonothinae and Xenoscelinae , and most erotylids, by the pronotum lacking a basal transverse groove and having a pair of submedial longitudinal pronotal grooves that are deep and widened posteriorly, have sharp edges laterad, and form part of a distinct rectilinear impression in the basal third.

Description. Length = 2.79 mm. Body ( Fig. 1 ) subcylindrical, mostly glabrous; unicolorous dark brown.

Head ( Figs. 1 A–D, 2A–C) with short tempora, 1/3 length of eye; without frontoclypeal suture; antennal insertion hidden in dorsal view; supraocular groove present and deep, extending posteriorly beyond eye, attaining occipital ridge; line connected to posterodorsal margin of eye, extending a short distance about the length of the eye; vertex with transverse line or ridge and two narrow stridulatory files widely separated; transverse gular line present. Antenna with 3-segmented club, extending to about mid-length of the pronotum; antennomeres of club not strongly flattened in cross-section. Eye small, coarsely faceted, with short ocular setae. Mandible ( Fig. 2B ) with two large apical teeth on the incisor lobe. Maxilla ( Fig. 2C ): palpomere 4 conical, distinctly longer than 3; lacinia with 2 apical spines curved inwards. Mentum without lateral pockets, medial carina present. Labium with simple apical palpomere. Genal spines well developed, apically rounded. Gular sutures incomplete, not reaching occipital foramen. Ligula with membrane almost as wide as prementum. Tentorium ( Fig. 2A ) with a small medial protuberance.

Thorax ( Figs. 1 , 2D, E ). Pronotum barely narrower than elytra, subcylindrical in cross-section and subparallel-sided, longer than wide, not constricted at base, anterior angles not projecting anteriorly, without a distinct flat glandular surface; lateral carina complete and simple, unitubulate pronotal glandular ducts opening at its surface; disc lacking a basal transverse groove and basal pronotal pits absent (note the deeply depressed corners of the depression may be homologous with the pits that are present in many other erotylids) and having a pair of submedial longitudinal pronotal grooves deepening at about the basal 1/3 and widened posteriorly, which have sharp edges laterad, and form part of a distinct rectilinear impression. Prosternum with anterior margin on same plane as disc, anterior edge serrate; without prosternal glandular ducts; procoxal cavity slightly externally open, mainly formed by strongly extended hypomeron, anterolateral notch weak; hypomeron with spinate edge. Scutellar shield clearly visible, heart shaped. Elytra with weekly impressed striate punctation, weakening significantly at lateral margins and posteriorly, scutellary striole absent, small humeral spine present, very narrowly explanate. Hind wing greatly reduced, narrow, shorter than metaventrite. Mesoventrite ( Fig. 1E ) with well-developed fovea located in procoxal rest (not outside of it), bearing unitubulate glandular ducts, with distinct ligulate space formed by longitudinal carinae converging posteriorly to the margin of mesoventrite and joined anteriorly; mesoventrital process about as wide as half diameter of mesocoxa; mesanepisternum with large fovea; metaventrite ( Fig. 1E ) with submesocoxal lines, without “pores”, premetacoxal lines absent, with discrimen more than 1/2 length of metaventrite, without posterior notch but weakly incised at middle of posterior margin; metanepisternum without ctenidium; metafurcal lamina absent; median stalk of metendosternite poorly developed. Legs ( Figs. 2D, E ) somewhat stout; tarsomere 1 almost as long as tarsomere 2; tarsomere 4 not strongly reduced, but slightly smaller than other tarsomeres; tarsomere 5 with small bifid tarsal shelf; empodial setae absent.

Abdomen with glandular ducts present at lateral areas of disc and posterior margins of ventrites, without abdominal calli; ventrite 1 with broad and rounded intercoxal process, with very short and divergent submetacoxal lines. Aedeagus ( Figs. 3 , 4 ) with extremely long biflagellate penile struts, with very long and thin internal sac; tegmen long, with articulated parameres.

Biology. Nothing is known about the biology of this monotypic genus, and the species is unique among pharaxonothines by having a highly reduced hind wing (brachypterous) and the associated character states which are also likely associated with brachyptery (metafurcal lamina absent and median stalk of metendosternite poorly developed). Unmodified, simple tarsomeres could also be associated with a ground-dwelling life history, but there are many apterous and brachypterous erotylids that have tarsomeres that are lobed or have distinct tarsal pads.

Distribution. Australia (Queensland).

Etymology. The name is composed of a prefix derived from Australia and a suffix derived from Pharaxonotha .

Figures

FIGURE 1. Australonotha monteithi gen. et sp. nov. A, Dorsal view, holotype; B, lateral view, holotype; C, dorso-lateral view, holotype; D, ventral view of head, holotype; E, ventral view of meso- and metaventrites, paratype. Scale bar: 1.0 mm for A–C; 0.5 mm for D, E.

FIGURE 2. Australonotha monteithi gen. et sp. nov., paratype. A, Head and tentorium, dorsal view; B, right mandible, dorsal view; C, right maxilla, dorsal view; D and E, middle leg, ventral view. Scale bar a: 0.5 mm for A, b: 0.2 mm for B, D, E; 0.1 mm for C.

FIGURE 3. Male genital structure of Australonotha monteithi gen. et sp. nov., paratype. A, Eighth and ninth abdominal segments, dorsal view; B, internal sac, median lobe, penile strut, lateral view. Scale bar: 0.5 mm for A; 1.0 mm for B.

FIGURE 4. Male genital structure of Australonotha monteithi gen. et sp. nov., paratype. A, Median lobe, lateral view; B, tegmen, dorsal view; C, parameres, ventral view. Scale bar: 0.2 mm.