Bomansius gabrieli Lacroix, 1978

Kakinuma, Shunsuke, 2019, A new species of Bomansius Lacroix (Coleoptera: Lucanidae) from Vanuatu, with redescriptions of its genus and its only congener, Bomansius gabrieli Lacroix, 1978, Insecta Mundi 728 (728), pp. 1-12 : 6-9

Bomansius gabrieli Lacroix, 1978

( Fig. 17–32 )

Bomansius gabrieli Lacroix 1978: 289 ; Maes 1992: 50; Mizunuma and Nagai 1994: 312, pl. 151, Fig. 148; Krajcik 2001: 23; Fujita 2010: 420, pl. 247, Fig. 1403

Type locality. Vanuatu (Nouvelles Hébrides). Erromango Island: Baie Dillon.

Material examined. Four males, six females ( SKC, MJPC): Vanuatu: Tafea Prov., Erromango Island, near Dillon’s Bay (= Baie Dillon).One male ( Fig. 33 ), MNHN, labeled: a) “NllesHébrides / E. Auber de / la Rüe 1936”; b) “ Bomansius / gabrieli / Lacroix / S. Boucher dét. 00.”

Distribution. Vanuatu (formerly New Hebrides): Erromango Island.

Redescription

Males (n = 5, Fig. 17–19 , 23–24 , 33 ): Length: (including mandibles) 11.5–16.9 mm. (excluding mandibles) 10.4–14.0 mm. Width: 5.4–7.8 mm. Color: Body usually black, sometimes brownish, with tibiae more or less brownish. Head: Widest at eyes (canthus). Labrum about 0.38–0.43× as wide as head (wider than 0.4× as wide as head except for very small specimen). Eyes almost but not totally divided ( Fig. 26–27 ) or totally divided ( Fig. 28–29, 30–31 : female) by canthi. Anterior canthus with minute setae from lateral view. Mentum with large and deep punctures. Pronotum: Form almost as wide as elytra; lateral edges crenulate, with short sparse setae; large punctures lined just in front of basal edge; lateral and basal edges with distinct bead. Elytra: Surface moderately glossy, covered with large to very large punctures; punctures mostly without setae, but on lateral and posterior declivity with very short to minute setae; elytral edge with short, sparse setae on lateral sides, denser posteriorly; elytral striae weakly or vaguely indicated; elytral edge with short, sparse setae on lateral sides; large and dense punctures visible from lateral view. Legs: Protibia almost straight or slightly curved interiorly, usually with two external teeth proximal to apex. Mesotibia with one very small external tooth below middle. Metatibia with a vestigial external tooth below middle. Setae in lines on mesotibia and metatibia dense. Abdomen: Apex of 5th ventrite with dense, long setae. Large males ( Fig. 17, 19 , 33 ): Dorsal surface of head and pronotum opaque, mostly with very fine, shallow, sparse punctures; mandibles almost as long as head; both inner teeth distinct. Pronotum with large, moderately dense punctures along lateral and posterior edges, few large punctures near anterior edge; lateral sides subparallel from near frond angles to basal third. Small males ( Fig. 18 , 23–24 ): Dorsal surface of head and pronotum moderately glossy; head smaller; surface with large, deep, dense punctures but finer on frons, around eyes and center; mandibles slightly shorter than head; inner teeth small, especially dorsomedial tooth. Pronotum almost entirely with large, deep, dense punctures; lateral sides rounded.

Females (n = 6, Fig. 20–22 ): Length: (including mandibles) 12.3–15.3 mm. (excluding mandibles) 11.1–13.5 mm. Width: 5.7–7.0 mm. Externally different from small males as follows: Body thicker and more convex overall. Head much narrower than males; labrum about 0.25× as wide as head, trapezoidal; mandibles acute, shorter, narrower, with one simple small internal tooth below middle; mentum narrower. Pronotum with lateral sides more rounded; lateral edges sinuous, with short setae sparser. Protibia broader. Mesotibia with a distinct external tooth below middle, often with one or more proximal small teeth. External teeth on mesotibia and metatibia more distinct. Setae in lines on mesotibia and metatibia sparser. Apex of 5th ventrite with only short, sparse setae.

Diagnosis. Bomansius gabrieli is similar to B. cheesmanae new species, but differs by having a smaller head, shorter and more weakly curved mandibles with a less steeply forward-projecting dorsomedial tooth and larger and distinct ventromedial tooth in males. The pronotum is shorter and not distinctly wider than the elytra in large males. Females have relatively shorter mandibles and larger and denser punctures on the pronotum. Both sexes display a pronotal basal edge with a row of large punctures, slightly more distinct elytral striae, and larger elytral punctures.

Notes. The holotype and allotype of Bomansius gabrieli are deposited in J.P. Lacroix’s collection; they are not available for study and the state of preservation is unknown since Lacroix’s death in 1989. The specimens I examined differ from the holotype description and somewhat poor illustration ( Fig. 25 ) as follows: anterolateral margin of head not concave; labrum narrower; supra-antennal brow less prominent; pronotum longer, with short setae on lateral sides; anterolateral corners of elytra not distinctly acute; elytral punctures distributed overall, not disappeared on distal third; protibia shorter, wider and less strongly curved; apical tooth of protibia obtuse, tibial spurs longer, tarsomere 1 clearly longer. According to the original description, length of the holotype male is 11.5 mm (including mandibles), the mandibles are 1.3 mm long and pronotum width is 6 mm, but the male having similar size examined in this study ( Fig. 24 , length including mandibles 11.5 mm, pronotum width 5.4 mm) has much less developed mandibles and a distinctly smaller head, much denser and larger punctures on the head and pronotum compared to the original drawing of the holotype male. Considering the morphological differences between large males and small males examined in this study, the measurements may be wrong and the holotype may actually be larger than the published length.

It is well known that sometimes the drawings of Lacroix did not totally conform to the specimens (L. Bartolozzi, pers. comm.)

One male in the MNHN ( Fig. 33 ) has been found and identified by Dr. S. Boucher in 2000 among many other undetermined insects from New Hebrides, Erromango forest, tree trunks, collected by Aubert de la Rüe in 1936. It is also historically relevant, as it is probably the first specimen ever collected (S. Boucher, pers. comm.). This specimen is different from other materials examined; the inner margin at the base of the mandibles of only has a few short and poorly visible setae, though this is possibly because the setae were abraded.

Figures

Figure 33. Bomansius gabrieli. Male (MNHN), dorsal habitus with labels and dissected genitalia.

Figures 17–22. Bomansius gabrieli. 17–19) Males. 17) Dorsal habitus. 18) Ventral habitus.19) Lateral habitus. 20–22) Females. 20) Dorsal habitus. 21) Ventral habitus. 22) Lateral habitus.

Figures 23–32. Bomansius gabrieli. 23–24) Males, dorsal habitus. 25) Holotype male (after Lacroix 1978). 26–31) Eyes. 26–27) Male, eyes not totally divided by canthi. 26) Dorsal view. 27) Lateral view. 28–29) Male, eyes totally divided by canthi. 28) Dorsal view. 29) Lateral view. 30–31. Female, eyes totally divided by canthi. 30) Dorsal view. 31) Lateral view. 32) Male aedeagus with sternite of 9th abdominal segment, ventral view.