Adelostoma muqalensis, Purchart, Luboš, 2017

Purchart, Luboš, 2017, Revision of the genus Adelostoma (Coleoptera: Tenebrionidae). Part 2: A new subgenus and species from Oman, Zootaxa 4258 (3), pp. 281-286 : 283-285

Adelostoma (Omandelostoma subgen. nov.) muqalensis sp. nov.

( Figs. 1–5 )

Type locality. Oman, Wadi Bani Khalid , Muqal cave.

Remark. The locality label mentions Munkal cave (“Munkal-Höhle”) which is an incorrect transcription of Muqal cave located in Wadi Bani Khalid in Ash Sharqiyah South Governorate, west Oman.

Type material. HOLOTYPE [unsexed] ( NHMW), labelled: OMAN, W, Bani Khalid / Munkal-Höhle / 700m a.s.l / 11.10.[20]06 [white, printed] // HOLOTYPUS / Adelostoma / muqalensis sp. nov. / det. L. Purchart 2016 [red, printed].

Remark. Collector of the new species is unknown.

Differential diagnosis. A. muqalensis sp. nov. possesses an epipleural carina which is only developed apically, a feature which is shared with all members of the subgenus Zarudnionymus. However, it can be distinguished from those species mainly by antennomeres IV-IX being longer than wide and especially by strongly elongated antennomere III being three times longer than antennomere II (in Zarudnionymus species antennomeres IV-IX are transverse and antennomere III is at maximum twice as long as antennomere II). Furthermore, the new species differs from the rest of its congeners by two midlongitudinal carinae on the disc of the pronotum which are developed only at the anterior fourth of pronotum, and by a large transverse impression in the middle of the pronotum (two pronotal carinae completely developed and no impression on pronotum present in the rest of the genus). Spaces between coarse and deep punctures on reflected portion of elytra are larger than puncture diameter in Omandelostoma subgen. nov., while in all Zarudnionymus species the spaces are smaller than puncture diameter. Last but not least, the new species differs by absence of long erect or semi-erect hairs on dorsal body surface (members of the subgenus Zarudnionymus are covered with long erect or semi-erect setae).

Description. Body length 7.6 mm, width 3.4 mm. Body narrow, elongate and glabrous. Dorsal and ventral sides of body pale brown (perhaps teneral specimen) and dull ( Figs 1, 2 ).

Head 0.95 times as long as wide, 0.6 times as wide as pronotum ( Fig. 4 ). Widest at genae. Shagreened, covered sparsely with short whitish hairs on genae and epistoma. Length of hairs approximately as long as two eye facets combined. Surface of head with net-like sculpturing composed of concave granules which are approximately 2–3 times larger than one eye facet. Genae strongly developed. Ocular carinae sharp, moderately high (in lateral view), parallel. Midlongitudinal carinae incomplete, short, starting before anterior part of eyes and reaching anterior margin of clypeus, approximately as high as ocular carinae (in lateral view). Depressed area between antennal sulcus and midlongitudinal carina large and deep. Clypeus asymmetrically cut out in the middle (left side deeper than right), with two small teeth in the middle ( Fig. 4 ). Antennae 1.66 times longer than width of head, covered with whitish hairs. Hairs approximately as long as three eye facets combined. All antennomeres longer than wide. Antennomere III strongly prolonged, approximately twice as long as antennomere IV and three times longer than antennomere II ( Fig. 3 ). Ultimate antennomere obliquely truncate and strongly widened towards apex, longer than wide, approximately one and a half times longer than penultimate antennomere. Antennal sulcus deep.

Pronotum strongly transverse, 1.77 times wider than long, with rounded sides, strongly narrowing anteriorly, widest in posterior third ( Fig. 5 ). Glabrous, shagreened, without net-like surface, sparsely covered with very small granules which are smaller than one eye facet. Anterior fourth with two parallel, very short midlongitudinal carinae in the middle. Anterior margin of pronotum strongly emarginated. Anterior angles of pronotum more or less rounded. Central part of pronotum with large and deep transverse impression. Lateral portions of pronotum foliaceous, distinctly bent upward. Lateral margins of pronotum slightly but more or less regularly dentate with very small teeth. Base of pronotum emarginated laterally and centrally, resulting in obtuse anterior angles and two large teeth, each situated between lateral and middle third of pronotal base.

Elytra glabrous, shagreened, ovoid, with three longitudinal, strongly developed and relatively high keels on each elytron ( Fig. 1, 2 ). Space between elytral suture and first (inner) keel irregularly deeply punctuate with 4–5 puncture interval. Space between first and second and second and third keel with 3–4 puncture intervals with punctures arranged more or less in rows. Surface between these punctures with very small tubercles smaller than one eye facet. First (inner, not elytral suture) and third (outer) keels connected anteriorly with basal margin of elytra. All three keels unconnected with each other or the apex of elytra. First carina beginning at level of metacoxae. Epipleural carina developed only apically. Reflected portion of elytra (sensu Koch 1952: 5, 7) at level of 1st and 2nd abdominal ventrites with five puncture intervals, with coarse and deep punctures arranged more or less irregularly, space between those punctures much bigger than their diameter. Apex of elytra moderately steep (lateral view).

Legs shagreened and covered with whittish setae, without any special features.

Ventral side. Mentum strongly transverse, subcordiform. Apical margin of buccal fissure lobes dentate, triangular (sensu Koch 1952: 15). Entire ventral side of head, pro-, meso- and metaventrite shagreened and sculptured with net-like pattern composed of concave granules. Ventral side of head covered with hairs similar to those on antennae. Prosternal process narrow, as broad as mesosternal and narrower than metasternal apophysis; subparallel, projecting behind procoxae, rounded apically (in dorsal view) and almost horizontal (in lateral view). Hypomeron and abdominal ventrites glabrous, shagreened, sparsely covered with fine granules similar to those on elytra. Each granule with recumbent, short setae.

Etymology. The name “ muqalensis ” refers to Muqal cave ( Oman) where the species was found.

Remark. Symphochora simoni (Fairmaire, 1894) and Adelostoma schawalleri Purchart, 2009 were the only members of the tribe Adelostomini that were considered as truly cavernicolous species so far ( Koch 1952; Purchart 2009). According to the locality label and also due to the considerably elongated antennomeres, which is one of the typical features for cavernicolous insects, A. muqalensis sp. nov. might be another member of the tribe Adelostomini which can be considered cavernicolous species as well.

Distribution. Oman—so far known from the type locality only.

Figures

FIGURES 1 – 5. Adelostoma muqalensis sp. nov., holotype. 1 — habitus, dorsal view; 2 — habitus lateral view; 3 — right antenna; 4 — head (white arrow indicates midlongitudinal carina on head); 5 — pronotum (white arrows indicate midlongitudinal carinae). Scale bars: Figs. 1, 2 = 2 mm; fig. 3 = 1 mm; figs. 4,5 = 0.5 mm.