Oryzaephilus socotraensis, Halstead, 2012

Halstead, David G. H., 2012, New species of Oryzaephilus and Silvanolomus from Socotra Island (Coleoptera: Silvanidae: Silvaninae), Acta Entomologica Musei Nationalis Pragae 52, pp. 223-231 : 224-227

Oryzaephilus socotraensis sp. nov.

( Figs.1 , 3–6 )

Oryzaephilus canus non Halstead, 1980: HALSTEAD (2011): 234 (misidentification).

Type locality. Yemen, Socotra Island, Noged plain, Sharet Halma vill. env., 12°21.9′N, 54°05.3′E, 20 m.

Type material. HOLOTYPE: dissected J, ( NMPC): ‘ YEMEN, SOCOTRA Island / Noged plain (sand dunes) / SHARET HALMA vill. env. / 12°21.9′N, 54°05.3′E, 20m / J. Bezděk leg., 10-11.xi.2010 ’. PARATYPES: 4 JJ 1 ♀, same data as holotype but JJ collected by Jiří Hájek and ♀ by Luboš Purchart ( NMPC, 1 J BMNH).

Additional material examined. 1 dissected J: ‘ YEMEN, SOQOTRA-ARCHIPEL, SOQOTRA/ Noged.Farmihin, Nähe Strand, Om./ 12˚ 24′ 41″ N, 54˚ 13′ 35″ E, 24.- 25.10.2000 / leg.: H. Pohl, SOQ 2000/04 // HLMD-Col-934’. Although this specimen has all the characters of the species and falls within the measurements given, it has not been included in the type series because it is badly damaged, particularly its pronotum, which is split down the middle.

Description. Dark brown to blackish-brown, moderately depressed and elongate (as usual for the genus). Length 2.4–2.8 mm (holotype: 2.4 mm); length: maximum elytral breadth ratio, 32.4–38.3: 10. Pubescence golden or greyish. Head and pronotum appearing dull, elytra more shining.

Head. As long or slightly longer than breadth across temples; genae (sides of head in front of eyes) obviously raised forming conspicuous rim (as in many other Oryzaephilus ), not sharply angled and without horns; small depressions above antennal insertions; eyes large, separated medially across head by about ×5–×7 breadth, separated from front of head by about ×1.5 length; temple length: eye length ratio, 10: 50–60; antennal length: body length ratio, males 10: 31.5–33.2, female 10: 35; head of usual size compared with pronotum (breadth across temples: pronotal maximum breadth, excluding anterior angles and other teeth, males 10: 11.3–11.5, female 10: 12.3); puncturation strongly reticulate on vertex.

Pronotum. Moderately elongate, length: maximum breadth (excluding anterior angles and other teeth) ratio, males 13.2–14.0: 10, female 13.0: 10 (probably tending to be less elongate in all females); lateral ridges well developed, somewhat curved in female, more or less parallel for greater length in males, median ridge higher than lateral ridges; anterior angles strongly produced forming very prominent laterally directed teeth (slightly more so in males than in female seen), see Figs. 3–4 , other teeth moderately developed; puncturation coarse, reticulate as on head, a few punctures reniform.

Elytra. Length: maximum breadth ratio, 18.7–22.6: 10; sides gradually curved to apex (apices curved to suture, not produced before it); third and alternate interstriae with setae arranged in three rows (usual herring-bone arrangement).

Metathoracic legs. Male, metatrochanter with spine, metatibia with minute spine near apex (metafemur without spine); female, without secondary sexual characters (as in other Oryzaephilus spp. ).

Male genitalia. ( Figs. 5–6 ). Internal sac with armature ( Fig. 5 , somewhat fragmented in specimen drawn); 11–13 rods on each side towards ostium; median strut strongly narrowed to basal half; median lobe with a few short setae on basal third, sinuate before broad, rounded apex; parameres elongate, more or less parallel sided, slightly curved to base from apical half, apices truncate to slightly rounded to outer margin, bearing four long apically forked setae plus two or three thinner, shorter simple setae towards outer margin, outer and inner margins below the apices with several short inconspicuous setae ( Fig. 6 ); sternites VIII–IX (not illustrated), sternite VIII with three longer setae present on outer half of margin of each side, finer very short setae medially.

Differential diagnosis. The following combination of characters distinguishes this from other known species: Eyes large and prominent; temples short, about a fifth or less as long as eye; anterior angles of pronotum strongly produced laterally to form a prominent, narrow tooth, obviously more strongly developed than all other teeth; pronotum not gibbous; male genitalia: internal sac with armature; median lobe without a ventral tooth, sides sinuate before broad apex; parameres elongate more or less parallel-sided, only a few short setae along outer margin (no long setae there).

A strongly developed tooth at the anterior pronotal angle, more prominent than the other teeth especially in larger males, is also present in O. gibbosus , an African species that has been found in Socotra (see below), and O. acuminatus Halstead, 1980 , an Oriental species. However, apart from having obviously different male genitalia (parameres and median lobe are quite different) the elytra of these two species appear more elongate, more parallel sided and at their apices usually have the margin slightly produced before meeting the suture, also the pronota of these species are to some extent gibbous, inconspicuously to (in large males) obviously so.

Males of Oryzaephilus canus Halstead, 1980 and the new species have the same secondary sexual characters of the hind legs; in both the metafemora are without a spine. Also their genitalia are similar although in O. socotraensis sp. nov. the parameres, apart from having long setae limited to the apices, are more elongate. In O. canus long setae are also present along the apical half of the outer margin of the parameres (see HALSTEAD 1980 for figures). The damaged J specimen of O. socotraensis sp. nov. from Farmihin was first seen in 2002, when it was mistakenly thought to be a form of O. canus with more prominent anterior pronotal angles, etc. Its true status became apparent when the author received additional specimens last year. [Unfortunately, the record of O. canus from Socotra that was included in HALSTEAD (2011) was based on the Farmihin specimen and consequently is wrong. However, O. canus occurs in Somalia, as well as other parts of East Africa, and in the United Arab Emirates, so perhaps it will be found in Socotra in the future.]

Etymology. The geographic species name has been used because Socotra is where it was first discovered.

Distribution. So far known only from two localities in Noged plain, Socotra Island.

Figures

Figs.1–2. Habitus, dorsal view. 1 – Oryzaephilus socotraensis sp. nov. (paratype, male); 2 – Silvanolomus depressus sp. nov. (holotype, male).

Figs. 3–7. Oryzaephilus spp. 3–6 – O. socotraensis sp. nov.: 3 – head, pronotum and elytra of male; 4 – head and pronotum of female; 5–6 – male genitalia, 5 – internal sac, 6 – genitalia without sac. 7 – O. gibbosus Aitken, 1965, median lobe and parameres of male genitalia (after HALSTEAD 1980). Scale bars = 1 mm (Figs. 3–4), 0.1 mm (Figs. 5–7).