Hlavaciellus extremalis Jałoszyński, 2011, sp. n.
Creators: name: Jałoszyński, Paweł
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Staphylinidae
Hlavaciellus
Hlavaciellus extremalis

description: Hlavaciellus extremalis sp. n.
(Figs. 28, 39, 40)
Type material. Holotype: MALAYSIA: ɗ, " SABAH \ Mt. Kinabalu \ 2600 m, 1.V.1987 \ Burckhardt - Löbl" [white, printed], " HLAVACIELLUS \ extremalis m. \ det. P. JAŁOSZYŃSKI, '09 \ HOLOTYPUS " [red, printed] (MHNG).
Diagnosis. Subhumeral lines rudimental, barely noticeable; head of males non-modified; antennomere III nearly twice as long as broad.
Description. BL 1.95. Body of male (Fig. 28) moderately convex, pigmentation light brown, vestiture yellowish.
Head large, HL 0.35, HW 0.50; vertex convex, not separated from frons; frons slightly flattened; clypeus convex; supraantennal tubercles prominent, sharply delimited from median part of frons; eyes large, strongly convex and coarsely faceted. Punctures on dorsal surface of head very fine, unevenly distributed, separated by spaces 1– 2 x as wide as puncture diameters; setae short, relatively dense, suberect. Antennae extremely long and slender, reaching 0.81 of BL, gradually but only slightly thickened up to antennomere XI, uniformly covered with thin, long, dense and suberect setae, AnL 1.58, antennomere I nearly twice as long as broad; II much narrower and shorter than I, only 1.1x as long as broad; III slightly broader and much longer than II, nearly twice as long as broad; IV as broad as III but slightly shorter, 1.7x as long as broad; V slightly larger than IV, 1.7x as long as broad; VI slightly larger than V, nearly twice as long as broad; VII distinctly larger than VI, twice as long as broad; VIII barely noticeably smaller than VII, nearly twice as long as broad; IX slightly larger than VIII, 1.8x as long as broad; X slightly longer and much broader than IX, 1.6x as long as broad; XI slightly broader than X, distinctly shorter than IX–X together.
FIGURES 29–40. Aedeagus in ventral (29, 31, 33, 35, 37, 39) and lateral (30, 32, 34, 36, 38, 40) views. 29, 30, Hlavaciellus adelphos sp. n. 31, 32, H. bifoveatus sp. n. 33, 34, H. metrios sp. n. 35, 36, H. miser sp. n. 37, 38, H. clandestinus sp. n. 39, 40 H. extremalis sp. n. Scale bars: 0.2 mm.
Pronotum in dorsal view trapezoidal with moderately convex anterior margin, broadest at base, PL 0.58, PW 0.80; sides strongly rounded in anterior third, slightly concave just behind middle and slightly but distinctly divergent in posterior third; hind angles slightly sharp but rounded; posterior margin shallowly biemarginate; ante-basal pits small but relatively deep and well defined, equally distant from posterior and lateral margins of pronotum; lateral edges indistinctly swollen on nearly entire length. Pronotal disc glossy, in middle covered with extremely fine and shallow punctures barely discernible under magnification 40x, unevenly distributed and separated by spaces 0.5– 3 x as wide as puncture diameters, punctures close to margins of pronotum are slightly larger and denser, but not coarse. Setae long, moderately dense, suberect to erect.
Elytra oval, moderately long, broadest between middle and anterior third, EL 1.03, EW 0.88, EI 1.17; basal pit on each elytron small but distinct, nearly adjacent to scutellum; subhumeral lines rudimental, each developed only as barely noticeable wrinkle at base of elytron; apices of elytra separately rounded. Punctures on basal third of each elytron more distinct than those on pronotum but very shallow and diffused, separated by spaces comparable to puncture diameters, gradually reducing in diameter and depth toward lateral margins and apices; setae similar to those on pronotum but slightly thicker. Hind wings not studied.
Legs slender and long, all tibiae nearly straight.
Metaventrite with deep postmesocoxal impressions, occupying nearly its entire length.
Aedeagus (Figs. 39, 40) very long and slender, AeL 0.50; median lobe with abruptly separated, slender, triangular and pointed apical part; internal armature nearly symmetrical; parameres in lateral view moderately broad, bent in subapical region and with strongly curved apices.
Female. Unknown.
Distribution. East Malaysia: Borneo, Sabah.
Etymology. The Latin epithet extremalis was chosen to underline the extremely long antennae and extremely short subhumeral lines in this species.
Remarks. The combination of non-modified head in males and extremely short, barely discernible subhumeral lines on the elytra are unambiguous diagnostic characters for this species. The variability of the subhumeral lines in Cephennodes was discussed by Jałoszyński (2007a), and this character was found too variable to be a useful diagnostic generic or subgeneric feature. However, it may be used as a supplementary character for defining groups of species within the genus. The strongly reduced subhumeral lines found in H. extremalis provide a new evidence for a high variability of this remarkable structure of the elytral base in otherwise morphologically very uniform group of species.
Key to species of Hlavaciellus Jałoszy ń ski (males only)
Note. To use the key, the entire vertex must be visible; if in a dry mounted specimen a part of vertex is concealed under the anterior margin of the pronotum, the specimen should be relaxed and its vertex exposed.
1 Head modified........................................................................................ 2
- Head non-modified................................................................................... 11
2 Body length <1.7 mm; Philippines ..................................................... H. promissor Jałoszyński
- Body length> 1.8 mm; Malay Peninsula and Borneo......................................................... 3
3 Head with median tuft of curly setae between frons and vertex............................ H. cirrus Jałoszyński, sp. n.
- Head without median tuft of setae......................................................................... 4
4 Posterior part of frons with pair of large round tubercles; antennomeres VI–XI in addition to suberect vestiture each with sev- eral long, straight setae on ventral surface............................................... H. vampirus Jałoszyński
- Frons without large tubercles; antennae uniformly covered with suberect setae..................................... 5
5 Posterior part of frons with broadly U-shaped transverse carina...................... H. peninsularis Jałoszyński, sp. n.
- Frons without U-shaped carina......................................................................... 6
6 Median, elongate and convex part of frons delimited at each side by distinct longitudinal groove................................................................................................. H. angustifrons Jałoszyński, sp. n.
- Median part of frons not separated by grooves............................................................... 7
7 Vertex separated from frons by entire transverse impression bordered anteriorly by transverse carina; frons with pair of large pits........................................................................ H. decoratus Jałoszyński, sp. n.
- Vertex separated from frons only by entire transverse impression or pair of shallow impressions, without transverse carina; frons without pair of deep pits............................................................................ 8
8 Vertex clearly separated from frons by entire transverse impression laterally reaching behind posterior margins of eyes.... 9
- Vertex indistinctly delimited from frons by pair of shallow impressions not reaching to posterior margins of eyes......... 10
9 Punctures on vertex much denser and larger than those on frons........................ H. smetanai Jałoszyński, sp. n.
- Punctures on vertex and frons similar, very fine and sparse................................ H. sabahensis Stevanoviċ
10 Antennomere III nearly twice as long as broad..................................... H. bifoveatus Jałoszyński, sp. n. - Antennomere III subquadrate ... H. adelphos Jałoszyński, sp. n.
11 Subhumeral lines on elytra rudimental, barely discernible............................. H. extremalis Jałoszyński, sp. n. - Subhumeral lines sharply marked, well visible.............................................................. 12 12 Antennomere XI 2.2x as long as broad; antennomere IV 1.5x as long as broad................ H. miser Jałoszyński, sp. n. - Antennomere XI 1.8–1.9x as long as broad; antennomere IV 1.05–1.2x as long as broad........................... 13 13 PW/PL 1.45; aedeagus stout...................................................... H. metrios Jałoszyński, sp. n. - PW/PL 1.36; aedeagus slender................................................ H. clandestinus Jałoszyński, sp. n.
description: Published as part of Jałoszyński, Paweł, 2011, Hlavaciellus Jałoszyński, 2006: eleven new species, detailed morphology and systematic position within Cephenniini (Coleoptera, Staphylinidae, Scydmaeninae), pp. 1-33 in Zootaxa 2763 on pages 17-20, DOI: 10.5281/zenodo.276822