Amborotubus Leschen and Carlton, 2004

Leschen, Richard A. B. & Carlton, Christopher E., 2004, A New tribe, Genus and Species of Nitidulid Beetle (Coleoptera: Nitidulidae: Nitidulinae) from Bolivia, The Coleopterists Bulletin 58 (3), pp. 443-451 : 443-451

Amborotubus Leschen and Carlton , new genus

( Figs. 1–13 )

Type Species. Amborotubus clarkei Leschen and Carlton , n. sp.

Diagnosis. Body tubulate and parallel-sided ( Figs. 1–3 ). Head partially retracted into prothorax. Frons with a concave impression. Notch present above antennal insertion. Clypeus bilobed, transverse anterior ridge or bead absent. Epipharynx with two setose lobes that are visible in dorsal view extending slightly beyond labral margin

443

444 ( Figs. 6–7 ). Antennal fossa contiguous with subclypeal area that is excavated with complex ridges. Mentum platelike and concealing prementum and maxillary lobes ( Figs. 3 , 9 ). Pronotal lateral carina asetose and explanate. Prosternum ( Fig. 3 ) and hypomeron strongly concave anteriorly and posteriorly, with glabrous ocular rests lying in front of coxae. Notosternal sutures absent. Mesoventrite visible in ventral view; procoxal and prosternal rests absent. Ventrite 1 with relatively narrow intercoxal process. Femora and tibiae flattened and broad ( Figs. 4–5 ); inside margin of femur with deep groove for insertion of tibia. Tarsal pads transverse and not well developed. Tip of pygidium exposed. Ovipositor with apical styli ( Figs. 11–12 ).

Description. Length 3.9 mm. Body tubulate and parallel-sided ( Figs. 1–3 ). Dorsum glabrous, venter with short decumbent golden setae. Head partially visible in dorsal view, partially retracted into prothorax ( Figs. 2 , 6 ); wider than long, and lacking a well defined neck; posterior edge dorsally with a pair of shallow incisions; vertex without carina; frons with a concave impression marked posteriorly with a transverse elongate line and anteriorly with a short transverse line; notch present above antennal insertion; frontoclypeal suture absent; clypeal apex bilobed with a deep notch, transverse anterior ridge or bead absent. Labrum articulated and visible between clypeal lobes; dorsally weakly carinate at middle; anteriorly excavated. Epipharynx with two well developed setose lobes, anteriorly protruding and visible in dorsal view ( Fig. 7 ). Eyes weakly protuberant, entire; interfacetal setae absent. Antennae with scape longer than wide and longer than pedicel, which is shorter than antennomere 3; funicle short; club compact and setose. Antennal insertions hidden from dorsal view; antennal fossa contiguous with excavate subclypeal area and possessing complex ridges; subantennal groove present and deep; bounded by eye and genae; genae produced well beyond mandibular articulations and apices slightly rounded. Gula extending only a short distance (not reaching level of eye). Posterior margin of head weakly excavate on each side of gular base. One pair of small transverse cervical sclerites present. Tentorium with deep apical pits present in antennal grooves; tentorial bridge bearing a well developed anterior median process. Mandible about equally as long as wide ( Fig. 8 ); apex unidentate with subapical tooth lying in more or less the same horizontal plane; prostheca present, moderately setose; basal mola present and weakly dentate, striate. Maxilla ( Fig. 10 ) and labium ( Fig. 9 ) retracted below mentum; palpomeres elongate, about 2 3 as long as wide. Maxilla with narrow lacinia, width equal to that of terminal palpomere, lacking apical teeth, bearing a complete fringe of fine setae; terminal palpomere about 3 3 longer than combined width of palpomeres 1 and 2. Labium with prementum rather narrow, apex of ligula rounded; terminal labial palpomere about 3 3 longer than basal palpomere. Mentum platelike, transverse, lacking carinae, and concealing prementum and maxillary lobes; apical margin trilobed, with lateral lobes broader and longer than middle lobe. Pronotum about as long as wide, widest at base; disc convex; sides subparallel at basal 1/4; lateral carinae complete, visible from above, simple, without marginal bead, glabrous and explanate, more predominately so posteriorly; anterior 446 angles not produced; posterior angles rounded; posterior margin straight, simple, without marginal bead. Prosternum and hypomeron strongly concave anteriorly and posteriorly, with glabrous ocular rests lying in front of coxae; prosternum at middle about as long as median length of prosternal process, moderately convex; anterior margin produced at middle. Notosternal sutures absent. Prosternal process parallel-sided, but abruptly expanded laterally at apex; apex with straight margin. Procoxal cavities transverse, closed externally by notal projections that fit into lateral expansions of prosternal process. Visible portion of scutellum transverse and apically angulate, about half as long as wide. Elytra about 1.5 times as long as wide and 2 times as long as pronotum; humerus absent; narrowly explanate throughout its lateral length, with margins visible above; epipleuron oblique with surface completely visible in lateral view; bearing a row of modified setae. Mesoventrite visible in ventral view; moderately convex at middle, rising ventrally at mesoventral process; procoxal and prosternal rests absent. Mesocoxal cavities narrowly separated by 1/5 width of mesocoxal cavity. Meso-metaventral junction simple, narrowly truncate. Metaventrite moderately short and convex, flattened at center; discrimen present throughout its length, but weakly indicated at middle; subcoxal area present with metaventral space (¼ axillary space) relatively narrow, delimited by a distinct line that originates at meso-metaventral joint and terminates near the lateral edge of the metaventrite; precoxal lines present and convex. Metacoxae narrowly separated 1/3 width of metacoxal cavity. Hind wing long and narrow, about 2 times longer than wide; anojugal lobe broad with anal notch distal from base, vein AP 3 þ 4 present; 3 veins present in medial field. Abdominal ventrites moderately convex; ventrites 1 and 2 connate; ventrite 1 with relatively narrow intercoxal process that is truncate apically, subcoxal bead present and well developed, lacking apical fringe of setae and membrane (which are present on remaining ventrites). Legs ( Figs. 4–5 ) visible in lateral view, no part concealed by ventral extensions of the pronotum and elytra. Femora flattened and broad; inside margin with deep groove for insertion of tibia, sides of groove sharp; profemur with sides of groove of the same depth; meso- and metafemoral grooves with anterior carinae larger. Tibiae flattened and broad with rounded apices, fitting into grooves present on 448 femora, with posterior surfaces concave, outer edges spinate, inner edge with a bead, apices bispinate with subapical patches of setae and shallow tarsal insertions; protibia longer than wide, anterior face of protibia with outer submarginal lines (inside line weakly impressed); metatibia with length and width equal, anterior face of metatibia without submarginal lines. Tarsi 5-5-5, tarsomeres 1–4 together 1.4 times longer than tarsomere 5; tarsal pads transverse and not well developed. Tip of pygidium exposed.

Female Terminalia ( Figs. 11–13 ). Sternite 8 with well-developed spiculum ventrale ( Fig. 13 ); base broad and hyaline. Ovipositor with tergite 9 (paraproct, Fig. 11 ) largely membranous; anterior half quadrate and containing a pair of oblique baculi with extensions continuing dorsally a short distance along anterior rim; posterior portion rather diamond-shape and contacting the gonocoxite posteriorly; tergite 10 (proctiger, Fig. 12 ) membranous containing a pair of elongate baculi, broad apically and narrowed anteriorly; gonocoxite ( Fig. 11 ) elongate and cylindrical; gonostylus present, 1/6 length of coxite.

Comments. Amborotubus is unusual within Nitidulidae . Many of the characters are unique, occurring nowhere else in the family (e.g., antennal fossa contiguous with excavated subclypeal area and labrum, maxillary lobes, prementum and bases of palpi retracted and concealed from view by mentum), which make it easy to recognize. It is superficially similar in appearance to some members of the Cychramptodini (Nitidulinae) , a group limited to Australia, but these have the ventral pronotal and elytral edges sharp (the epipleuron completely hidden in lateral view) and other characters that distinguish the members of this tribe from Amborotubus (e.g., tarsal pads well developed, mesoventrite hidden in ventral view, etc.). Among the tribe Cychramptodini , Amborotubus most closely resembles members of Cylindroramus Kirejtshuk and Lawrence by its elongate body form with exposed pygidium, but members of this genus can be distinguished from Amborotubus by the legs hidden in lateral view. Some species of Cylindroramus have a deeply divided labrum that looks superficially like the epipharyngeal lobes present in Amborotubus , but this condition is quite widespread in the family. A notched or emarginate clypeus occurs in some Lawrencerosini and in Ecnomaeus (Cillaeinae) , but in these, the notch is rather broad and not as deep and narrowed as it is in Amborotubus .

Outside of nitidulines, Amborotubus is similar to members of Pityophagus Shuckard (Cryptarchinae) , but the typical Cryptarchinae characters (e.g., fused clypeus and labrum and presence of notosternal sutures) are absent in Amborotubus .

Etymology. The name is a combination of the prefix, Amboro -, named after the nearby park, Amboro Parque Nacional, established through the efforts of Robin Clarke, and the suffix - tubus, Latin for pipe and referring to the tubulate body shape.

Figures

Figs 1–2. Amborotubus clarkei. 1) Dorsal habitus; 2) lateral view. Scale bars ¼ 1 mm.

Fig. 3. Amborotubus clarkei, ventral habitus. Scale bar ¼ 1 mm.

Figs. 4–6. Amborotubus clarkei. 4) Anterior view of right front leg; 5) anterior view of hind left leg; 6) anterior view of head and pronotum. Scale bars ¼ 1 mm.

Figs. 7–13. Amborotubus clarkei. 7) Epipharynx; 8) right mandible (dorsal view); 9) mentum and labium (anterior-oblique view); 10) right maxilla (ventral view); 11) ventral view of ovipositor (retracted), tergite 9 (paraproct), and relative positions of sternite 8 and tergite 10; 12) dorsal view of terminalia showing tergite 10 and relative positions of the ovipositor and tergite 9; 13) sternite 8 (spiculum ventrale). Scale bar ¼ 0.3 mm. BA ¼ baculum, GC ¼ gonocoxite, GS ¼ gonostylus, S8 ¼ sternite 8, T9 ¼ tergite 9, T10 ¼ tergite 10.