Silidius svihlai, Geiser, 2017

Geiser, Michael, 2017, First record of the family Cantharidae on Socotra, with description of a new genus and two new species of the subfamily Silinae (Coleoptera: Elateroidea), Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 57, pp. 93-99 : 94-96

Silidius svihlai sp. nov.

( Figs 1–4 )

Type locality. Yemen, Socotra Island, Hagher Mts., Wadi Madar.

Type material. HOLOTYPE: J, ‘ YEMEN, SOCOTRA ISLAND, 18.vi. / Hagher Mts. , WADI MADAR, 2012 / montane shrubland with / Cephalocroton socotranus / 12°33.2′N, 54°00.4′E, 1170 m // SOCOTRA expedition 2012 / J. Bezděk, J. Hájek, V. Hula, / P. Kment, I. Malenovský, / J. Niedobová & L. Purchart leg.’ ( NMPC) . PARATYPES: 3 JJ with same data as holotype ( NMPC, BMNH), one of them also bearing the label ‘? Silidius / sp. / V. Švihla det. 2012 ’; 1 ♀, ‘ YEMEN, SOCOTRA ISLAND / Dixam plateau, TUDHEN / shrubland with Commiphora / planifrons, 18.+ 22.vi.2012 / 12°32.7′N, 53°59.9′E, 1135 m // SOCOTRA expedition 2012 / J. Bezděk, J. Hájek, V. Hula, / P. Kment, I. Malenovský, / J. Niedobová & L. Purchart leg.’ ( NMPC) .

Description. Male ( Fig. 1 ): Orange testaceous, head black between and behind eyes, elytra black with narrow yellowish stripe running along extreme margin, starting below humeral callus and disappearing in posterior third, antennae mostly black, with antennomeres I, II (except extreme apex) and sometimes base of antennomere III orange, tarsi dorsally infuscate, scutellum orange.

Head moderately shining, loosely covered in greyish or golden pubescence arising from fine punctures. Diameter of eyes roughly equivalent to length of antennal scape. Antennae subfiliform, reaching until apical half of elytra, scape not thickened and slightly longer than antennomere III. Antennomere II shortest, about 2/3 of length of III; III shorter than IV; IV–XI subequal in length, slightly shorter than II and III together.

Pronotum as in Fig. 3 , transverse, its front part semicircular with angles bluntly rounded, base distinctly narrower than front half and with rounded angles. Front margin explanate, anterior half of lateral margins with raised lobe-like structure with clearly delimited recurrent margin, independent from, but parallel to margin of pronotum (probably homologous to structure described as ‘lappenförmige Platte’ or ‘Lappen’ by WITTMER 1969: 220). Lateral margin produced into rounded, flat lobe dorsally near middle, followed by sharply projecting, slightly excavate appendage underneath.

Scutellum with rounded apex, of similar structure as elytra.

Elytra slightly lustrous, rather glabrous around scutellum and with more leathery texture towards apex, loosely covered in fine, greyish recumbent pubescence, arising from very fine punctures; without any traces of costae.

Outer claw of each tarsus deeply cleft.

Abdomen very weakly sclerotised and with very fine, inconspicuous yellowish pubescence. Apical tergite simple, not emarginate and without modifications. Apical ventrite split into two transverse, rounded lobes.

Aedeagus as in Fig. 2 . Two produced lobes of dorsal shield (‘Dorsalschild’) as well as large laterophyses heavily sclerotised and darkened towards their apex. Inside of dorsal shield with pair of blackish teeth, directed inwards.

Female. Same colour pattern as in male, antennae distinctly shorter, reaching only to basal half of elytra, pronotum as in Fig. 4 , without modifications, transversely subrectangular with rounded angles, slightly elevated near posterior angles.

Measurements. Total body length: 6.1–7.6 mm; length or elytra: 4.2–5.5 mm; width of elytra: 2.0– 2.5 mm (J), 2.9 mm (♀); length of pronotum: 1.2–1.5 mm; width of pronotum 1.5–1.9 mm (J), 2.0 mm (♀); width of head: 1.3–1.5 mm.

Differential diagnosis. Based on the claw morphology (one claw bifid on each tarsus in males, female claws simple), this species is placed here within Silidius . However, the structure of the male pronotum and aedeagus, plus the absence of modifications on the last tergite separate this species from any known species of that genus and make it difficult to compare to any of the species from continental Africa. For females, the colour pattern, including the yellow lateral margin of the elytra is also rather characteristic.

Etymology. Named in honour of my late colleague RNDr. Vladimír Švihla (Prague), who had studied this species before, but was not able to describe it before passing away in 2015. During an earlier meeting at NMPC in 2012, it was Vladimír who encouraged me to study the neglected subfamily Silinae .

Distribution. Only known from the mountainous interior of Socotra Island.

Figures

Figs 1–4. Silidius svihlai sp. nov. 1 – holotype, dorsal habitus; 2 – male genitalia, ventral view; 3 – pronotum of male; 4 – pronotum of female. Scale bars represent 1 mm; longer scale bar refers to Figs 2–4.