Drilus rectus Schaufuss, 1867

Kundrata, Robin, Kobieluszova, Lucie & Bocak, Ladislav, 2014, A review of Drilini (Coleoptera: Elateridae: Agrypninae) of the Northern Levant, with description of a new species from Syria and a key to Levantine species, Zootaxa 3755 (5), pp. 457-469 : 465-466

Drilus rectus Schaufuss, 1867

( Figs 5 , 11, 17 , 23 )

Drilus rectus Schaufuss, 1867: 84 .

Material examined. 1 male, Dr.F. Leuthner / BEIRUT, 4.85 / SYRIEN. // coll. Reitter ( MHNP); 1 male, Syria // Coll. Reitter? // det. W. Wittmer ( HNHM); 1 male, Beyruth // det. J. Frivaldszky ( HNHM); 1 male, Syrien / Haifa / Reitter // Coll. Reitter? // det. W. Wittmer ( HNHM); 2 males, Beirut // Collect. Türk // det. Reitt. 1894 ( NHMW); 1 male, Appl / Beirut / 1878. // det. Reitt. 1894 ( NHMW).

Diagnosis. Drilus rectus is similar to D. akbesianus and D. nemethi sp. nov. ( Figs 2–5 ), but differs in smaller eyes, the head including eyes narrower or as wide as anterior pronotal margin ( Figs 2, 4–5 ), and parallel-sided lateral margins of paramerae ( Figs 20, 22–23 ).

Redescription. Male. Body medium-sized, elongate, 2.9–3.4 times longer than width at humeri, moderately convex dorsally ( Fig. 5 ). Body mostly dark brown to black, only antennomeres 1–2, prothorax, scutellum, mesoventrite, legs, last two abdominal ventrites and in some cases elytral sutura yellowish to light brown; whole body covered with yellow pubescence.

Head slightly hypognathous, including eyes slightly narrower or as wide as anterior margin of pronotum. Surface of cranium punctured, with moderately deep depression between conspicuous antennal sockets, dorsally with long sparse semierect pubescence; clypeus with margin widely emarginate. Eyes medium-sized, hemispherically prominent, their frontal distance 2.0–2.1 times eye diameter. Mandibles long, considerably curved, shiny, incisor margin with tooth in middle part. Maxillary palpi slender, apical palpomere with slightly compressed and obliquely cut apex; labial palpi tiny, apical palpomere pointed. Antennae 11-segmented, reaching third of elytral length, scapus long, robust, pedicel short, small, antennomere 3 serrate, more than 3 times longer than antennomere 2, antennomeres 4–10 shortly flabellate, subequal in length; apical antennomere longest, simple, slightly longer than lamella of penultimate antennomere ( Fig. 11 ).

Pronotum flat, widest at basal margin, 1.4–1.6 times wider posteriorly than length at midline. Anterior margin almost straight or slightly notched in middle, lateral margins convex, posterior margin emarginate medially. Anterior angles almost rectangular, posterior angles obtuse or prominent ( Fig. 17 ); surface of disc coarsely punctured, with sparse, semierect, long setae. Scutellum flat, triangle-shaped, apically rounded. Prosternum transverse, prosternal process short, slightly elevated in middle part. Mesoventrite narrow, v-shaped. Metaventrite large, trapezoidal, sparsely punctured. Elytra subparallel-sided, widest at basal part, 2.3–2.6 times longer than widest at humeri, tapered apically, sparsely punctured. Each elytron covered with semierect, long, uniformly distributed pubescence. Abdomen short, slender, ventrites with fine microstructure and sparse, long setae. Legs slender, slightly compressed, with dense, long, semierect setae, coxae long, robust, trochanters slender, obliquely attached to femora, tarsomeres 1–3 subequal in length, tarsomere 4 shortest, apical tarsomere long, claws simple, slender, slightly curved.

Male genitalia with phallus longer than paramerae, more or less tapering towards apex in dorsoventral view, considerably curved; paramerae with lateral margins parallel-sided or slightly convex, with sparse setae, apical parts more or less membranous; phallobase robust, always longer than paramerae ( Fig. 23 ).

Measurements. BL 6.5–8.1 mm, EL 5.2–6.5 mm, WH 2.1–2.6 mm, PL 1.0– 1.3 mm, PW 1.5–2.1 mm, Edist 0.9–1.1 mm, Ediam 0.5 mm.

Distribution. Israel ( Finkel et al. 2002), Lebanon, southern Turkey ( Hatay province). This species is also reported from Cyprus (Baudi di Selve 1871), but the relationship between Cyprian and Levantine mainland populations needs further investigation.

Remarks. Schaufuss (1867) described Drilus rectus from Beirut ( Lebanon) and Antiochia (i.e., Antakya in Hatay province, Turkey). He mentioned that specimens in his collection vary in the shape of depression between eyes, the cuticular structure of head and the shape of pronotal posterior angles. Although we were limited by the lack of specimens from Turkey, we observed the differences in the characters listed above and in the shape of aedeagi among specimens from different Lebanese D. rectus populations. D. rectus can be potentially misidentified as D. frontalis Schaufuss, 1867 which is not known from the Levant and occurs in southern Turkey (Mersin province). According to Schaufuss (1867), D. rectus differs from D. frontalis in the following characters: body size (7.5–8 mm in D. rectus , 4.5 mm in D. frontalis ), the shapes of the pronotum, scutellum and the penultimate ventrite (shallowly emarginate in D. rectus , deeply in D. frontalis ). However, the body size in Drilini commonly varies even within one population ( Kundrata 2012) and the shapes of the penultimate ventrite and pronotum vary even among Lebanese populations of D. rectus . What more, Schaufuss (1867) described D. frontalis from a single specimen so he could not properly study the intra- and interspecific variability. Reitter (1894) erroneously stated in contrast with original descriptions that both D. rectus and D. frontalis are about 8 mm long and that D. frontalis has yellow or red colored head. Both species, however, have black-colored head ( Schaufuss 1867). Schaufuss's types including D. rectus and D. frontalis are probably lost and we have an opportunity to study neither D. frontalis (described originally from Mersin) nor D. rectus specimens from southern Turkey, Syria and Israel. Therefore, further detailed investigation of these species is needed to understand their relationship.

Figures

FIGURES 1 – 6. General appearance. 1 — Drilus adustus; 2 — D. akbesianus; 3 — D. bicolor; 4 — D. nemethi sp. nov.; 5 — D. rectus; 6 — D. rufipes. Scale 2.0 mm.

FIGURES 7 – 18. Antenna. 7 — Drilus adustus; 8 — D. akbesianus; 9 — D. bicolor; 10 — D. nemethi sp. nov.; 11 — D. rectus; 12 — D. rufipes. Pronotum. 13 — Drilus adustus; 14 — D. akbesianus; 15 — D. bicolor; 16 — D. nemethi sp. nov.; 17 — D. rectus; 18 — D. rufipes. Scale 1.0 mm (Figs 7 – 12), 0.5 mm (Figs 13 – 18).

FIGURES 19 – 24. Male genitalia. 19 — Drilus adustus; 20 — D. akbesianus; 21 — D. bicolor; 22 — D. nemethi sp. nov.; 23 — D. rectus; 24 — D. rufipes. Scale 0.25 mm.