Dinas (s. str.) strakai, Skuhrovec & Batelka, 2014

Skuhrovec, JiĜí & Batelka, Jan, 2014, Taxonomy of the Cape Verde endemic weevil genus Dinas (Coleoptera: Curculionidae: Entiminae). Part I: Description of a new subgenus, and two new species from São Nicolau Island, Acta Entomologica Musei Nationalis Pragae 54 (1), pp. 315-336 : 327-329

Dinas (s. str.) strakai sp. nov.

( Figs 2B, 2D, 2F, 2H , 4A–D )

Type locality. Cape Verde Isl., E of São Nicolau, Tope de Chuva, 16°36ƍ6.05ƎN, 24°7ƍ26.8ƎW.

Type material examined. HOLOTYPE: 3, ‘ CAPE VERDE Isl. / SAO NICOLAU, E, Tope / de Chuva, 10.xi.2011, / 16°36’6.05”N, 24°7’26.8”W / J. Batelka & J. Straka lgt. [printed label]’ ( SMNS). PARATYPES: 4 33, the same as holotype ( SMNS, 13 JSKC). Specimens of the newly described species are provided with one red printed label: ‘ Holotype [or Paratype] / DINAS (s. str.) / STRAKAI sp. nov. / JiĜí Skuhrovec & / Jan Batelka design. 2013’.

Additional material examined. 7 elytra, the same as holotype (6 SMNS, 1 JSKC). Specimens are provided with one white printed label: ‘ DINAS (s. str.) / STRAKAI Skuhrovec & Batelka, 2013 / JiĜí Skuhrovec & / Jan Batelka det. 2013’.

Description ( Figs 2B, 2D, 2F, 2H , 4A ). Body black, scape, distal part of tarsal segment III and last tarsal segment with claws reddish to brownish. Frons, whole rostrum and scape with sparse pale short erect setae. Coloration and presence of setae on the remaining antennal segments unknown, all studied specimens missed all antennal segments except scape.

Pronotal vestiture black with pale, short, slightly erect setae, which are distinctly shorter than claws; circular small whitish scales sometimes with feeble green lustre on upper margin, lateral sides and bottom of pronotum, dorsal surface of pronotum without scales. Elytral vestiture black, covered with small circular to slightly oval whitish scales with feeble green lustre. Scales present on following parts of elytra: from 4(5) interval to lateral sides along whole elytral length and apical third of 1–4(5) intervals; basal two third of elytra of 1–4(5) intervals very rarely with few scales, normally without scales. Elytral intervals and apex of elytra with pale, very short, slightly erect setae, which are distinctly shorter than claws. Scutellum bald. Femora black with pale setae and rarely small, oval whitish scales with feeble green lustre. Tibiae black with pale setae and distinct small, oval scales. Tibiae bearing stout, yellowish to slightly brownish bristles apically. Tarsi dark reddish to brown (black) with pale setae. First three segments on all tarsi with small projecting scales (“soles”). Claws reddish to brownish.

Black abdomen covered with whitish scales sometimes with feeble green lustre.

Head ( Fig. 2B ). Eyes elliptical, distinctly convex, ventral apex narrower than dorsal. Narrowest vertex distance distinctly shorter than base of rostrum. Rostrum slightly narrower than its length (ratio = 0.85–0.95) enlarged anteriad, tapered to medial part and than enlarged posteriad. Epistome large and distinct; epistomial keel distinctly well developed. Frons not separated from epifrons by any distinct carina, but with distinct protuberances. Epifrons enlarged from the medial part, strikingly anteriad and also posteriad; with distinct median longitudinal deep furrow in the whole length of epifrons, which reaches to vertex and also occiput, or only distinct deep pit in line with anterior margin of eyes; along median longitudinal deep furrow before eyes with a few transversal shallow striae ( Fig. 2B ). Scrobes distinct and deep; in dorsal view visible for more than two thirds of length; in lateral view curved, strikingly enlarged posteriad, dorsal border directed towards ventral border of the eyes and almost reaching them, ventral border directed below eyes; in front of antennal insertion broad, short and well visible. Occiput distinct, behind eyes distinct shallow striae.

Antennae inserted in one-third of rostrum from rostrum apex. Scape (as long as rostrum) narrow and elongated, extended behind posterior margin of eyes, slightly bent and widened apically. Funicle and club unknown, all known specimens lacking it, ratio of scape and funicle is unknown.

Pronotum ( Fig. 2D ) more wide than long (ratio = 1.2–1.3) and widest near middle; anterior margin nearly straight in dorsal view; sides distinctly rounded; posterior margin showing equal width to anterior margin; basal constriction noticeable and lacking distinct protuberances, markedly bent, not flat and well visible from lateral and dorsal views; tubercles distinct on whole surface except middle part, where form flat angle V, in middle with slightly noticeable furrow.

Elytra ( Fig. 2H ). Slightly subglobose elytra that is longer than wide (ratio = 1.05–1.15) with base as wide as widest part of pronotum, without humeral angle; very slightly convex sides. Elytral striae small and only with shallow but distinct punctures, mainly along elytral suture, elytral striae closed to apex and elytral sides almost not recognizable. Elytral striae line in two not well distinct rows, striae in apical third in zig-zag arrangement, than in two parallel rows and sometimes still in zig-zag arrangement. Elytral intervals slightly prominent, but narrower than line of elytral striae.

Legs. All femora with small but distinct spina ( Fig. 2F ), distinctly widest near middle. All tibiae apically distinctly widened and incurved. Tarsi with ¿rst tarsal segment distinctly longer than second, third distinctly bilobed, ¿fth twice as long as ¿rst.

Abdomen. Abdominal ventrite 1 bearing distinct depression (typical character of males). Suture between abdominal ventrites 1 and 2 slightly but distinctly sinuose and shallow; next sutures straight and deep. Abdominal ventrites 1–2 approximately of same width, but twice the length of abdominal ventrites 3 and 4 each. Last abdominal ventrite with shallow impression medially.

Sexual dimorphism unknown because only male specimens has been reported.

Male genitalia. Penis ( Fig. 4B ) gradually slightly narrowed from base to basal 1/ 5 in dorsal view, then parallel-sided. Ventral plate distinctly and triangularly narrowed toward top. Apodeme of penis as long as median lobe. Penis in lateral view strongly curved in basal third, then less strongly curved until subapically. Spiculum gastrale ( Fig. 4C ) stick-formed, slightly curved and of subequal length with median lobe of penis.

Variation. Dinas strakai sp. nov. is extremely variable in body length: 7.2–9.3 mm. The median longitudinal furrow on epifrons also vary, especially in the length (it reaches to vertex or up to occiput) and also in the number of striae along furrow ( Fig. 2B ). Shape of pronotum and elytra may slightly differ, mainly in specimens that are not completely sclerotised. No variability was observed in colouration or the structures of male genitalia. The majority of specimens is not in good condition, because all specimens were found dead under stones and we did not ¿nd any complete specimen.

Differential diagnosis. The new species is the second known species of the subgenus Dinas (s. str.), aside from the type species D. rugicollis . Dinas strakai sp. nov. differs from the latter species by elytral striae being divided at the elytral base (or slightly more posteriorly) in two arranged rows ( Fig. 4D ), while D. rugicollis has the elytral striae only in one row ( Fig. 4E ). Although only males of D. strakai are available, the state of this character has never been observed as a sexual dimorphism in weevils.

Comments. The length of the median longitudinal deep furrow and presence of striae along this furrow on the epifrons in Dinas strakai is variable, and we only know the character state for the male (females are unknown). In D. rugicollis the situation is opposite, because we know of only one female. Thus we cannot compare such variable characters as the median longitudinal furrow on the epifrons or the genitalia. The coloration is also useless because the type of D. rugicollis may be partially immature.

Etymology. The new species is named in honour of Jakub Straka (Czech specialist in Hymenopetra), one of the collectors.

Bionomics. Dinas strakai sp. nov. from Tope de Chuva was collected exclusively under stones close to the top of the rim of the old caldera.

Distribution. Cape Verde Islands – São Nicolau (eastern part), circa 600 m a.s.l.

Figures

Fig. 2. Differential diagnosis of the subgenera of Dinas: Dinas (Microspina) afonsoi sp. nov.:A – head, dorsal view; C – pronotum; G – elytra, dorsal view; Dinas (Microspina) sitonaeformis Wollaston, 1867: E – spina on profemora; Dinas (s. str.) strakai sp. nov.: B – variability of rostrum of Dinas (s. str.) strakai sp. nov., dorsal view; D – pronotum; F – spina on profemora; H – elytra, male, dorsal view.

Fig. 4. Dinas (s. str.) strakai sp. nov., holotype, male (A–D): A – habitus, dorsal view; B – aedeagus, dorsal and lateral view; C – spiculum gastrale; D – elytra, dorsal view; E – elytra of Dinas (s. str.) rugicollis Wollaston, 1867, dorsal view. Scales: 1 mm, scale with ‘*’=2 mm.