Jubogaster, Parker & Maruyama, 2013

Parker, Joseph & Maruyama, Munetoshi, 2013, Jubogaster towai, a new Neotropical genus and species of Trogastrini (Coleoptera: Staphylinidae: Pselaphinae) exhibiting myrmecophily and extreme body enlargement, Zootaxa 3630 (2), pp. 369-378 : 371-372

Jubogaster gen. nov.

Type species. Jubogaster towai sp. nov. here designated.

Diagnosis. Euplectite pselaphines with the following characters: transverse head articulating ventrally under pronotum when deflexed, typical of Trogastrini . Head with vertex excavate, lacking vertexal fovea; ventral head without the typical dense “genal beard” of setae common to most Trogastrini . Eleven-segmented moderately geniculate antennae, received by large excavations anterior to eyes. Pronotum jubine-like: broad and obcordate, constricted at basal quarter, with weakly-evident medial longitudinal sulcus and distinct antebasal sulcus. Pronotum afoveate, with margins smooth, devoid of crenulations or small spines found in other Trogastrini . Elytra lacking any stereotypical fovea. Legs with contiguous, projecting coxae, broad femora, basally flattened tibia, and three tarsal segments; segment 1 very small, 2 and 3 elongate and subequal in length. Tarsi with two equally-sized claws, unlike other Trogastrini which have unequally-sized claws. Bifid anterior protarsal claw in the type species J. towai .

Etymology. A combination of Jubus Schaufuss and Trogaster Sharp , the type genera of Jubini and Trogastrini , respectively. The name is chosen on account of the membership of the new genus in Trogastrini , despite apparent Jubini-like characters such as the shape of the pronotum and the presence of two equally-sized tarsal claws (a character state found in Jubini, but not other Euplectitae). The bifid anterior protarsal claw of the type species J. towai is also shared with Phamisus myrmophilus Silvestri of Jubini.

Description. Body large (5.1mm for the type species J. towai shown in Figure 1 ). Body shape approximately ovoid and strongly convex.

Head: Approximately triangular, strongly transverse ( Fig 4 ). Vertex afoveate, concave, with moderately deep excavation extending from basal quarter to anterior margin of frons; excavation narrowing apically along midline as it passes between raised frontolateral margins. Frontolateral margins carinate, extending roughly arcuately from posterior of antennal insertion cavity to clypeus ( Fig 5 ). Frontolateral face accommodating large circular cavity anterior to eyes to receive antennae ( Fig 5 ). Eye flanked directly anteriorly by additional large excavation for retracted maxillary palpus ( Fig 5 ). Ventral surface of head bisected by longitudinal gular carina situated within broader gular sulcus terminating in gular fovea. Gular sulcus widens basally, spanning the head-neck interface. Maxillary palpi apparently 4-segmented, with segment II long and curved at apex, III short and triangular, wider than II, IV oval, approximately 2x longer than wide ( Fig 5 ). Antennae ( Fig 3 ) with 11 antennomeres, moderately geniculate with enlarged segment I. Antennomeres IX – XI strongly elongate (XI longest).

Thorax: Pronotum ( Fig 4 ) obcordate, 2x wider than head, almost as wide as elytra. Afoveate, with smooth margins. Anterior margin broadly arcuate, largely obscuring the deflexed head when viewed from above, and constricted sharply in basal quarter, so that pronotum is laterally expanded into broad, blunt spurs with curved edges. Medial longitudinal sulcus present on pronotal disc, weakly impressed, thin, terminating at deeper, bowshaped antebasal sulcus that extends between bases of mediolateral spurs. Prosternum afoveate, with lateral longitudinal carinae extending from sides of neck to base. Mesosternum with median mesosternal foveae (MMSF), lateral mesosternal fovea (LMSF) and lateral mesocoxal fovea (LMCF) present. Other typical pselaphine mesosternal fovea listed in Chandler (2001) lacking. Metasternum strongly convex. Lateral metathoracic foveae (LMTF) present; median metathoracic fovea (MMTF) absent.

Abdomen: Abdomen with tergites strongly convex. Visible segments 1 – 3 (IV – VI) subequal in length ( Fig 1 ), segment 4 (VII) longest (not apparent in Fig 1 due to curvature of abdomen). Tergites 1 – 3 (IV – VI) with pronounced paratergites, 4 (VII) with small tapering paratergites. Tergite 6 (IX) internalised. Six sternites visible ( Fig 2 ), sternite 7 (IX) internalised. First visible sternite (III) with median process projecting between metacoxae. Sternites 2 and 3 (IV and V) subequal in length, 4 (VI) slightly shorter ( Fig 2 ).

Elytra: Strongly convex, slightly broader than pronotum ( Fig 1 ), approximately 0.3x total body length. At their longest, equal in length to visible abdominal segments 2+3 (V+VI) combined. Elytral humeri broadly rounded to almost half elytral length. Sutural stria entire; lacking sutural fovea and other stereotypical antebasal fovea. Lacking subhumeral fovea and subhumeral stria. One weakly defined, somewhat discal depression is evident halfway between suture and humerus; its homology to canonical pselaphine antebasal elytral fovea is unclear.

Legs: All coxae contiguous ( Fig 2 ), procoxae conical, projecting ventrally, mesocoxae globose, metacoxae ( Fig 7 ) transverse-conical, spanning from ventral midline to metasternal margin, and projecting posteriorly. Femora somewhat thickened, and excavated apically to receive retracted tibia. Tibia flattened basally. Femora and tibia lacking spines or processes. Tarsi elongate, 3-segmented, first segment extremely short, 0.2x the length of segment 2. Segment 2 and 3 subequal in length. All tarsi with 2 well-developed, equally-sized tarsal claws. Bifid anterior protarsal claw in type species J. towai ( Fig 8 ).

Figures

FIGURES 1 – 7. Jubogaster towai Parker and Maruyama. 1) dorsal habitus 2) ventral habitus 3) left antenna, exterior face is to the left 4) vertex of head and pronotum 5) frontal of view of head, showing excavations for antennae and maxillary palpi 6) right elytron apical angle showing excision 7) left metacoxa, metatrochanter with arrow pointing to rhomboid-shaped tubercle.

FIGURES 8 – 10. 8) apical protarsus showing bifid anterior protarsal claw 9) aedeagus, ventral view 10) aedeagus, dorsal view.