Discheramocephalus vasilii Darby, 2013

Jałoszyński, Paweł, 2020, Notes on Malagasy Discheramocephalus Johnson (Coleoptera: Ptiliidae), Zootaxa 4885 (4), pp. 591-595 : 593-594

Discheramocephalus vasilii Darby

( Fig. 1–3 , 7 , 10–12 )

Discheramocephalus vasilii Darby, 2013: 241 , Fig. 2 , 20, 22–25, 28.

Material studied: 1 ♁, Madagascar, Ranomafana National Park , 21.26S, 47.43E, 900–1000 m, 12.04.2019, sifted from leaf litter in secondary forest, leg. P. Jałoszyński ( MNHW) .

Emended diagnosis. Head with arcuate, anteriorly convex frontal groove accompanied at each side by elongate, oblique impression and with a pair of large shallow impressions each near mesal margin of supraantennal region; pronotum with six pairs of longitudinal sulci, of which only the lateral pair reaches anterior pronotal margin, each of four median sulci strongly broadened behind middle, pronotum with transverse, oval antebasal impression between the two lateralmost sulci; all antennomeres less than 3 times as long as broad; ‘cavities’ of abdominal segment VIII in male conspicuously large, each about as broad as 1/4 width of segment; posterior margin of sternite IX in male with broad median area devoid of denticles; aedeagus slender, in dorsal view parallel-sided between base and distal 1/4, in lateral view weakly sinuate.

Supplementary description. Head in male with paired impressions, these internally with smooth surface, not filled with setae ( Fig. 1–2 ); antennomeres 3–9 elongate but each less than 3 times as long as broad ( Fig. 3 ); male abdominal segment VIII ( Fig. 7 ) with a pair of large internal ‘cavities’, each nearly as broad as 1/4 of width of segment; posterior margin of sternite IX in male ( Fig. 10 ) with 4–5 sharp denticles on each side, median area arcuate, lacking denticles.

Aedeagus ( Fig. 11– 12 ) slender and conspicuously large, ~1/3 as long as body, in dorsal view ( Fig. 11 ) parallelsided from base to distal 1/4, in lateral view ( Fig. 12 ) weakly sinuate; endophallic structures indistinct, with numerous transverse folds of internal sac barely discernible under light microscope (better so with phase contrast).

Remarks. Details of the aedeagus and abdominal structures were not described previously for this species. As a part of diagnosis, “large, shallow, setae bearing pits on the head” were mentioned by Darby (2013). His SEM micrographs of the pronotum and head ( Darby 2013: Fig. 20) agree with the characters seen in the specimen examined during the present study. The antenna ( Darby 2013: Fig. 28) generally agrees with that illustrated here ( Fig. 3 ), although with slight differences in the shape of some flagellomeres. Similar differences between the antennae of D. bisulcatus figured by Darby (2013: Fig. 27) and that in Fig. 6 in the present paper can be seen, and they can be attributed to different study methods (light microscopy of a specimen in liquid medium and hand drawing, vs. SEM of dried specimens). A close-up of the head of D. vasilii in Darby (2013 : Fig. 23–24) shows paired impressions, similar to those found during the present study, except that there is another, small median impression in front of the transverse arcuate sulcus. The impressions do not seem to bear any setae, but appear as filled with dirt. The same paired impressions in the specimen examined and illustrated in the present study ( Fig. 2 ) are smooth and empty, and the median impression is missing. The presence and absence of the latter may reflect variability within species, or sexual dimorphism (the specimen illustrated by Darby (2013) is of unknown sex).

Discheramocephalus vasilii , as noted by Darby (2013), shares the same number of pronotal sulci with D. elisa- bethae Grebennikov, 2008, and D. mikaeli Grebennikov, 2008 . Discheramocephalus elisabethae [ Cameroon] lacks the arcuate transverse frontal groove, its postocular transverse groove bears submedian longitudinal carinulae flanking a narrow smooth area, and the four median pronotal sulci are indistinctly broadening posterad. Each of these characters is different in D. vasilii , which has a transverse frontal groove on the head, the smooth median region of the postocular groove not demarcated by longitudinal carinulae, and the pronotal sulci strongly, almost abruptly broadening posterad. Discheramocephalus mikaeli [ Tanzania] differs from D. vasilii in the same cephalic characters as D. elisabethae , and additionally in the median pair of pronotal sulci much broader and reaching anterior pronotal margin, vs. narrow and not reaching the anterior margin in D. vasilii .

Figures

FIGURES 1–6. Discheramocephalus vasilii Darby, male (1–3), and D. bisulcatus Darby, male (4–6). Dorsal habitus (1, 4); head, pronotum and elytral base in dorsal view (2, 5); antenna in dorsal view (3, 6).

FIGURES 7–9. Abdominal internal ‘cavities’ of segment VIII. Discheramocephalus vasilii Darby, male (7); D. bisulcatus Darby, male (8) and female (9).

FIGURES 10–18. Discheramocephalus vasilii Darby, male (10–12), and D. bisulcatus Darby, male (13, 15–17) and female (14, 18). Posterior margin of abdominal sternite IX (10, 13–14); aedeagus in dorsal (11, 15) and lateral (12, 17) views; apex of aedeagus in dorsal view (16); spermatheca (18).