Baeoceroxidium Ogawa & Löbl, 2013

Ogawa, Ryo & Löbl, Ivan, 2013, A revision of the genus Baeocera in Japan, with a new genus of the tribe Scaphisomatini (Coleoptera, Staphylinidae, Scaphidiinae), Zootaxa 3652 (3), pp. 301-326 : 323

Baeoceroxidium Ogawa & Löbl , gen. nov.

Type species: Scaphosoma micros Achard, 1923 .

Diagonosis. Maxillary palpomere IV aciculate ( Fig. 43 ). Antennomeres III and IV elongate; VII–X asymmetrical. Mandibles bidentate ( Fig. 42 ). Galea wider than long; brush apical and paniculate ( Fig. 43 ). Surface of mentum setose ( Fig. 45 ). Submentum trilobe ( Fig. 46 ). Anterior margin of pronotum with a bead. Hypomeron without fovea. Prothoracic corbiculum absent. Mesocoxal lines present on metaventrite. Metendosternum with stem present. Secondary lines of mesoventrite absent. Abdominal ventrite I without metacoxal bead (metacoxal line). Profemoral ctenidium present. Mesotibia with 2 ventral spines. Metacoxae contiguous. Empodium unisetose.

Description. Body form dorsally convex and oval. Dorsal setae reduced. Pronotal and elytral carinae hidden in dorsal view.

Head with labral setae present and apically pointed. Mandible with apex bifid, subapical serrations present. Maxillary palps normal, palpomere 3 with some setae. Galea wide, not narrow and radulate, with brush apical. Lacinia narrow, with lateral setae. Hypopharyngeal setae present and setose. Labial palps normal; insertion of terminal palpomere reduced, with 1 seta. Mentum with straight edge. Apex of submentum trilobed, surface with 2 setae. Gular suture not reaching submentum. Frontoclypeal suture present. Eye entire; interocular distance large. Antennal insertion hidden; level to or below midline of eye. Antenna filiform; antennomeres III and IV elongate; antennomeres VII–XI asymmetrical.

Prothorax with corbiculum absent. Prosternum with anterior portion of procoxal cavity asetose; prosternal process anteriorly spinate. Anterior bead of pronotum present. Hypomeron entirely visible in lateral view; apex not extended beyond hind margin of pronotum. Pronotal carina prominent with bead. Prothoracic angle rounded, not extending well below epipleural line and not reaching anapleural suture.

Mesoventral space (prepectus) present. Mesoventral lines present. Secondary lines absent. Mesoventral process paxillate. Median lines absent. Mesepimeron present; as long as about one half of full length of anapleural line. Width of intercoxal process equal to that of coxa.

Metaventrite partially fused to mesoventrite. Mesocoxae round. Mesocoxal lines parallel to coxa and punctate; not connected at middle. Setiferous patch absent; primary setae present and discal. Premetacoxal lines and discrimen absent; intercoxal plate present. Metanepisternal suture punctuate. Metanepisternum mostly exposed, without longitudinal line. Metendosternal stem present. Metacoxal process digitate. Hind coxae distant.

Pterothorax with scutellum exposed between elytral bases, about as wide as one third of pteronotal length; scutellar lines type III (cf. Leschen & Löbl 2005). Hind wings present. Elytron with basal and lateral striae present; apical serrations weak.

Abdomen with submetacoxal space absent; submetacoxal lines punctate and not connected at middle. Two primary setae present on disc of ventrite I. Abdominal ventrites slightly setose. Paratergites of segments IV and segment VI present. Spiracle 8 absent. Aedeagal sclerites simple and rod-like.

Profemora with ctenidium. Pro- and mesotibiae without basal spines. Tibiae smooth; mesotibia longer than mesotarsus; outer mesotibial spines absent; two inner mesotibial spines present, one twice as long as second. Mesotarsomere I larger than II. Metatarsi smooth. Empodium unisetose.

Distribution. Japan, India, Thailand.

Etymology. This genus name (gender neuter) is derived from Baeocera and Toxidium .

Comments. Baeoceroxidium micros shares with the single known species of Kasibaeocera , K. mussardi (Löbl, 1971) , a number of diagnostic characteristics, in particular the mouthparts and the shape of the pronotum. However, Baeoceroxidium and Kasibaeocera may be readily distinguished by the prothoracic corbiculum that is present in the latter species. The members of the Baeocera pilifera group also lack the prothoracic corbiculum, and have bidentate mandibles, wide galea, short posterior angles of pronotum, and symmetrical aedeagus with wide, notched, and setose parameres. Therefore, they are transferred to Baeoceroxidium.

The new genus shares a number of characteristics with taxa of the Toxidium group, although the body is not compressed laterally. In particular, these taxa lack prothoracic corbiculum and have the maxillary galea wider than long, bidentate mandibles, and setose and widened parameres of the aedeagus. Therefore, we place the new genus within the Toxidium group. In the key to the Scaphisomatini genera (Leschen & Löbl, 2005: 19) Baeoceroxidium falls under the couplet 16, for Baeocera and Kasibaeocera . It has aciculate palpomere 4 unlike Kasibaeocera , and mandibles with two apical teeth, unlike Baeocera .

Figures

FIGURES 41 – 46. Mouthparts of Baeoceroxidium micros. 41, Labrum; 42, mandible; 43, maxilla; 44, labium; 45, mentum; 46, submentum. Scales: 0.05 mm.