Diplocheila (Diplocheila) erwini, Allegro & Giachino, 2021
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|Diplocheila (Diplocheila) erwini|
Cambodia, Kampong Chhnang, Khom Domnatpopol, Tonle Sap Lake.
Paratypes: (1 ♂ and 3 ♀♀); 1 ♀ same data as holotype GoogleMaps ; 1 ♂ Cambodia, Kampong Chhnang, Rolea B’ier District, Toulkrolanh Village , 12°13'31"N, 104°39'50"E, light trap, 7.XI.2018, W. Rossi and V. Kong leg. GoogleMaps ; 2 ♀♀, Cambodia, Kampong Chhnang, banks of Tonle Sap Lake , light trap, 17.V.2019, W. Rossi and V. Kong leg. (CAl, CGi) .
A medium-sized to small Diplocheila (ABL: 12-14 mm) of the Diplocheila polita group in the subgenus Diplocheila Diplocheila (sensu Ball 1959). It is easily distinguished from the other species of the group with a sexsetose labrum ( D. indus , D. laevigata , D. laevigotoides , and D. walterrossii sp. nov.) by the smaller body size (≤14 mm), the narrower and almost quadrangular pronotum (transverse in the four other species), with hind angles not protruding (protruding in D. indus ), and by the morphology of the aedeagus.
Habitus: ABL: 12-14 mm (HT ♂ 13.5 mm). Body parallel-sided, moderately shiny, black with antennae and palpi piceous-brown (Fig. 5 View Figure 5 ).
Head: almost quadrangular, glabrous except for the supraorbital setae, narrow in comparison with pronotum. Eyes markedly convex; a single supraorbital seta on each side. Dorsum with microsculpture not evident, only with scattered punctures visible at >100 × magnification; frontal impressions short and superficial. Labrum symmetrically and deeply (LR = 0.78) emarginate, with six setigerous punctures on anterior margin (4 medial equidistant + 2 lateral on lobes). Clypeus trapezoid, distinctly concave anteriorly, with 1 seta on each side at anterolateral corner. Antennae moderately long, densely pubescent from segment 4, with terminal 2 articles surpassing base of pronotum; segments elongate, the second one short, as long as a half of first. Mandibles elongate, broad, approximately similar each another (the left with apical cutting edge more concave), with scrobe well-defined and glabrous and apex blunt; terebral tooth triangular and prominent. Labial and maxillary palps fusiform, with apices narrowly truncate.
Thorax: pronotum smooth, with very faint microsculpture evident at >200 × magnification and with scattered punctures, subquadrate (PW/PL = 1.18), widest at middle (Fig. 11 View Figures 6–11 ). Disk moderately convex. Sides from rectilinear to hardly rounded in anterior half; rectilinear or very slightly sinuate backwards. Hind angles rounded obtuse, provided with a postero-lateral seta. Posterior margin rectilinear between basal impressions, which are linear and markedly impressed; anterior margin with front angles nearly obsolete. A single lateral seta on each side just above middle. Lateral bead continuous, separated from the discal area by a narrow groove, only scarcely dilated before hind angles. Medial longitudinal impression fine, nearly reaching anterior and posterior margins; anterior transversal impression absent.
Elytra: moderately long (EL/EW = 1.59), parallel-sided, slightly convex and flattened on disk, widest at middle, with rounded shoulders and sides delicately sinuate before apex. Surface moderately shiny; microsculpture evident only at high magnification (>100 ×), consisting of fine, slightly transverse meshes. Epipleura without any distinct external plicae ("uncrossed epipleura"). Intervals moderately convex, smooth; striae deeply impressed on the whole length, distinctly punctate. Parascutellar stria present; scutellar setigerous pore present at base of stria 1, just before conjunction with stria 2. Basal margin complete. Discal setigerous punctures absent; umbilicate series of setigerous punctures continuous, not interrupted at middle. Hind wings fully developed.
Ventral surface (thorax and abdomen): prosternum and proepisterna glabrous and impunctate (only with very fine punctures). Metepisterna as long as twice the width of anterior side; metepimera large, broadly rounded. Prosternal intercoxal process widely rounded and bordered at apex. Abdominal ventrites IV-VI shiny but shagreened at sides, glabrous except one pair subapical central setae; males with 2, females with 4 marginal setae at apex of ventrite VII.
Legs: moderately slender. Posterior face of femora with 1 seta in profemora, 2 in mesofemora and metafemora. Metatrochanters glabrous and slightly shorter than half length of metafemora. Protibial antennal cleaning organ well developed, with 2 clip setae. Protibiae robust, with 4 or 5 outer apical spines; mesotibiae with a group of setae at middle of inner face; metatibiae longitudinally furrowed at inner face. Dorsal face of tarsomeres smooth. Male protarsomeres 1-3 distinctly dilated, slightly asymmetrical; meso- and metatarsomeres not dilated in both sexes; tarsomere 5 ventrally glabrous, dorsally with 2 apical setae; claws smooth.
Male genitalia: median lobe of aedeagus short and markedly swollen before apex in lateral view (Fig. 23 View Figures 20–25 ); the apical lamella shortly triangular in dorsal view, with blunt tip (Fig. 30 View Figures 26–32 ), apex very slightly bent downwards in lateral view. Ostium long, in dorsal position. Right paramere oval; left paramere conchoid.
This species is named, as a token of our esteem, after our late colleague Terry Erwin, a world-renowned specialist in world and tropical Carabidae .
Distribution and ecology.
Geographical distribution : this species is recorded only from the extreme south banks of the Tonle Sap Lake, Kampong Chhnang Province, Cambodia. It seems to have a more restricted Geographical distribution than D. walterrossii sp. nov., which has been recorded from the same site as well as from other two localities in north-western Cambodia (Fig. 33 View Figure 33 ). Life habits: the specimens of the type series were collected on lake banks by light trapping. No other data are available.
It is difficult to assess the closest relatives of D. erwini sp. nov. It belongs to the D. polita group (sensu Ball 1959), as it shares the characters distinguishing this group and, moreover, its aedeagus is very similar to that of D. polita (see pl. V, fig. 72a in Ball 1959). Diplocheila erwini sp. nov., on the other hand, is easily distinguished from D. polita which has a quadrisetose labrum and pronotum more transverse (PW/PL = 1.31 according to Fig. 26 View Figures 26–32 in Plate II in Ball 1959), as well as a larger body size (ABL = 13.4-18.4) ( Ball 1959).
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