Omniops, Perkins, P. D. & Short, A. E. Z., 2004

Perkins, P. D. & Short, A. E. Z., 2004, Omniops gen. n. and two new species of Hydrophilini from Papua New Guinea (Coleoptera: Hydrophilidae), Zootaxa 494, pp. 1-14 : 2-3

Omniops gen. n.

Type species: Omniops fasciatus sp. n.

Etymology. Derived from Latin omnis “all” and ops “means”; gender masculine.

Description. 2.33–2.85 mm. Form broadly oval; moderately convex. Lateral canthus of frons extending in front of eyes, creating a dorsal and ventral surface ( Fig. 9 ); clypeus extended anteriorly in front of eyes; series of systematic punctures present mesad of each eye. Frontoclypeal suture very distinct, without sculpture except laterally in front of eye; lacking midlongitudinal extension across frons. Clypeus, viewed dorsally, straight across anterior one­third, then angulate to eyes. Labrum partially retracted beneath clypeus; with dense row of fine, long setae. Maxillary palpi short, subequal in length as width of mentum; with four segments, first segment minute, ratio of lengths of segments 2/3/4 as 7:5:10; second segment swollen. Antennae with eight segments; scape slightly more than 2x length of pedicillus; segment 5 slightly cuspulate; segments 6–8 forming a loosely segmented pubescent club with segment 8 nearly as large as segments 6 and 7 combined. Point of antennal insertion concealed dorsally by the clypeus. Mentum mostly glabrous, moderately sinuate anteriorly. Gula well developed. Posterior tentorial pits moderately separated. Pronotum with indistinct systematic punctures present, sometimes bearing short setae. General punctation on head and pronotum very shallow, with distinct, very fine microreticulation. Prosternum tectiform; bearing moderately dense covering of setae. Mesosternum bearing a high, ventrally directed protuberance. Scutellum slightly longer than wide. Elytra evenly convex, not flattened dorsally; with sharp sutural stria in at least posterior half; margins not explanate. Elytra with general punctation uniformly distributed; with rows of serial punctures not well developed to nearly absent; punctures not microreticulate. Epipleura wide, slightly wider than the width of anepisternum 3. All femora with tibial grooves; ventral surface of pro­ and mesofemora with dense pubescence on at least basal three fourths; metafemora with pubescence restricted to extreme base and along anterior margin. All tarsi with five segments; tarsomeres 1–4 subequal in length; tarsomere 5 on pro­ and mesotarsus as long as tarsomeres 1–4 combined, and two­thirds as long on metatarsus. Both tarsal claws small and similar on all legs. Abdomen with five exposed flat ventrites covered with dense, fine pubescence; first ventrite without median carina; fifth ventrite arcuate posteromedially, marginal setae larger than other pubescence on ventrites.

Discussion. Omniops differs from other genera in the Acidocerina in possessing a row of long setae on the labrum ( Figs. 8 , 16 ). The presence of divided eyes, relatively wide epipleura and short maxillary palpi are shared with Quadriops . The lack of an emargination on the fifth exposed ventrite is uncommonly observed in the subtribe.

Omniops also differs from Quadriops in many characters, including having a very strong protuberance of the mesosternum, having non­explanate elytra, and lacking strong rows of serial punctures on the elytra. The mentum of Quadriops is concave medially and has a deep U­shaped apicomedial notch, whereas the mentum of Omniops is only slightly emarginate apically and not concave on the middle of the disc. The prosternum of Quadriops is flat and has an arcuate anterior margin, whereas Omniops has a low median rise, a transverse sulcus, and the anterior margin is produced in a small point apicomedially. The hind femora of Quadriops lacks hydrofuge pubescence, whereas in Omniops there is a distinct band of pubescence along the anterior margin and at the base.

Although habitat data are not available for members of Omniops , the dorsal habitus, the orientation of the maxillary palpi, and the extent of the ventral hydrofuge pubescence suggest aquatic habits. Contrastingly, members of Quadriops have been collected by sifting litter, and may not be aquatic.

Figures

FIGURES 8 – 9. Omniops fasciatus holotype. — 8. Dorsum of head. — 9. Divided eye.

FIGURES 16 ­ 17. Omniops hanseni holotype. — 16. Dorsum of head. — 17. Venter of head.