Philothis (Philothis) arcanus Reichardt 1930
Creators: name: Lackner, Tomáš
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Histeridae
Philothis
Philothis arcanus

description: Philothis (Philothis) arcanus Reichardt, 1930
(Figs. 32, 44, 63, 97, 128, 525–542)
Philothis (Philothis) arcanus Reichardt, 1930: 295, Figs. 8, 11, 12, 13.
Philothis (Philothis) arcanus: REICHARDT (1941): 339, 342, Figs.73, 175A; KRYZHANOVSKIJ & REICHARDT (1976):244, 246, Fig. 475; MAZUR (1984): 109; OLEXA (1990): 153, Fig. 19; MAZUR (1997): 268; MAZUR (2004): 96.
Type locality. Uzbekistan, Farab.
Type material examined. HOLOTYPE: spec., ‘Buchara occ. / Farab. / 3.iv.[1]911 / A. Hohlbeck // Philothis / arcanus sp. n. / Holotyp / Reichardt det. [printed-written] // Coll. Semenov-Tian-Shansky [printed] // with another golden round label’ (ZIN). PARATYPE: 1 spec., ‘Buchara occ. / Farab. / 16.iv.[1]912 / A. Hohlbeck [printed-written] // Coll. Semenov-Tian-Shansky [printed] // Philothis / arcanus sp. n. / P-typ / Reichardt det [printed-written] // with another golden round label’ (MNHN).
Additional material examined. UZBEKISTAN: Buchara, Shafrikan, 29.iv.1979, 1 ♁, A. Olexa lgt.; Karakum, Chiva [= Khiva], 3.v.1978, 1 ♁, A. Olexa lgt.; ditto, but 1.–5.v.1979, 4 spec.; Kyzylkum, Buchara, 30.iv.1979, 1 ♁, A. Olexa lgt. (TLAN).
Redescription. Body length: PEL: 1.975 –2.175 mm; APW: 0.75–0.80 mm; PPW: 1.50–1.75 mm; EL: 1.225 –1.425 mm; EW: 1.925–2.00 mm.
Body (Figs. 525–526) roundly oval, moderately convex from above, underside very convex, cuticle light to dark brown, shining; legs, mouthparts and antennal scape rufopiceous.
Antennal scape (Fig. 529) thickened, imbricate, with numerous long setae; club (Fig. 528) comparatively small, round, without visible articulation, apical third imbricate, with thick dense short erect yellow sensilla concealing apical sensory area; basal surface glabrous; sensory structures of antennal club (Fig. 32) in form of one doubled apical sensory area and one stipe-shaped vesicle situated under it.
Mouthparts. Mandibles (Fig. 97) with straight outer margin strongly curved inwardly, mandibular apex sharply pointed; sub-apical tooth on inner margin of left mandible moderately large, perpendicular; labrum (Figs. 44, 63, 527) smooth, flattened, slightly depressed medially; labral pits and setae absent; labral process significantly developed; terminal labial palpomere elongated, its width about one-third its length; mentum sub-trapezoid, finely imbricate, with shallow emargination in middle of anterior margin (Fig. 128), surrounded with numerous moderately long ramose setae, lateral margins with single row of much shorter ramose setae; cardo of maxilla on lateral margin with numerous short setae; stipes triangular, with numerous much longer setae; terminal maxillary palpomere thickened, apically truncate, its width about half its length, approximately twice as long as penultimate.
Clypeus (Fig. 527) rectangular, rounded laterally, smooth; frontal stria (Fig. 529) broadly interrupted medially, continued as well impressed and carinate supraorbital stria; frontal disc smooth; eyes flattened, invisible from above.
Pronotal sides (Fig. 525) moderately convergent anteriorly; apical angles obtuse; marginal pronotal stria well impressed, laterally carinate, broadly interrupted behind head; pronotal disc convex, entirely smooth, except for a row of small round punctures along base; posteromedian part with two vague bulges; pronotal hypomeron with long yellow setae; scutellum very small, almost invisible.
Elytra with prominent elytral humeri, elytral epipleura almost smooth, only with microscopic punctation; marginal epipleural stria complete; marginal elytral stria well impressed, carinate, continued as complete apical elytral stria. Humeral elytral stria distinctly impressed on basal third, occasionally doubled; inner subhumeral stria present medially, at times joining humeral elytral stria; outer subhumeral stria shortly present on basal fifth; first dorsal elytral stria shortened on basal third and apical fourth, on both ends bent inwardly, second dorsal elytral stria vaguely impressed as short fragment on apical half (at times completely absent); other dorsal elytral striae absent. Sutural elytral stria well impressed, apically connected with complete apical elytral stria, on basal half somewhat distanced from elytral suture, continuous as basal elytral stria surrounding large transverse bulge situated at median part of elytral base, vaguely connected with first dorsal elytral stria; elytral suture depressed; interspace between elytral suture and sutural elytral stria smooth. Elytral disc with dense, shallow obscurelyvariolate punctation, interspaces with microsculpture, punctation becomes leathery apically; area around scutellum, elytral humeri, flanks and transverse basal bulge glabrous.
Propygidium (Fig. 534) completely exposed, almost twice as broad as long, areolate-rugose; pygidium (Fig. 534) almost as long as broad, convex, medially areolate-rugose, laterally almost glabrous, slightly obscurely-variolate.
Anterior margin of median portion of prosternum (Fig. 531) almost straight, slightly emarginate medially; marginal prosternal stria present only laterally; prosternal process concave, setose, substrigulate; both sets of prosternal striae absent.
Anterior margin of mesoventrite with large shallow emargination; discal marginal mesoventral stria well impressed, carinate; disc with scattered shallow elongate punctures separated about their own to twice their own diameter; meso-metaventral sutural stria well impressed, almost straight, carinate; intercoxal disc of metaventrite medially with shallow scattered punctures, laterally smooth; posterior margin with coarser punctation; in male with shallow longitudinal depression; lateral metaventral stria well impressed, carinate, obliquely arcuate, shortened; lateral disc of metaventrite (Fig. 532) concave, with shallow round punctures fringed with long setae; metepisternum + fused metepimeron (Fig. 532) setose, punctation almost unrecognizable beneath setae; area of fused metepimeron depressed, setae less dense than on metepisternum.
Intercoxal disc of the first abdominal sternite almost completely striate laterally, with scattered microscopic punctation; lateral disc of all visible abdominal sternites setose laterally.
Protibia (Fig. 535) dilated, anterior margin truncate, formed by anterior margin of distalmost large triangular tooth; outer margin of protibia apart from this tooth with another, slighty shorter triangular tooth, both teeth topped with short rounded blunt denticle; setae of outer row confined to basal third, thin, sparse and moderately long; setae of median row thicker, more regular and dense; protarsal groove moderately deep; apical margin of protibia posteriorly without denticles; outer part of posterior surface of protibia smooth, distinctly separated from smooth median part of posterior surface by thin complete stria; posterior protibial stria shortened apically; inner margin of protibia with long lamelliform dense setae; protibial spur rudimentary, almost invisible, entombed in apical margin of protibia; protarsus rudimentary, apical tarsomere with single thin claw, approximately twice as long as apical tarsomere itself.
Mesotibia (Fig. 530) somewhat dilated, not particularly thickened, outer margin with one double row of sparse, morphologically different short denticles significantly growing in size and density near tarsal insertion, denticles continuous anteriorly along apical margin; setae of outer row growing out near inner mesotibial margin, dense and long, covering almost entire posterior mesotibial surface; setae of median row absent; posterior mesotibial stria shortened, present only on basal half; mesotibial spur conspicuously long and stout; outer part of median surface of mesotibia almost smooth, only with scattered microscopic punctation, anterior mesotibial stria thin, almost complete; inner margin of mesotibia with dense row of long lamelliform setae; mesotarsus (Fig. 533) telescope-like, diameter of tarsomeres diminishing apically, each tarsomere with two long lamelliform, strongly sclerotized setae, one dorsally and one ventrally; claws of apical mesotarsomeres thin, hair-like, several times as long as mesotarsomeres itself. Metatibia conspicuously dilated, outer margin with double row (short rounded and dense, thinner, longer denticles) of morphologically different denticles, another row of short sparser round denticles markedly shifted from it, present on anterior surface of metatibia and only observable from ventral view. Posterior surface of metatibia with dense rows of short setae, distinction between outer and median row unclear; posterior metatibial stria inconspicuous (absent?); metatibia otherwise similar to mesotibia.
Male genitalia. Eighth sternite (Figs. 536–537) longitudinally fused medially, apically with large inflatable membrane (velum); fringed with single thin short seta; eighth tergite and eighth sternite fused laterally (Fig. 538). Morphology of 9 th tergite (Figs. 539–540) typical for the subfamily; spiculum gastrale (Fig. 539) expanded on both ends. Basal piece of aedeagus (Figs. 541–542) rather short, ratio of its length: length of parameres 1: 3.5; parameres fused along their basal three-fourths; aedeagus conspicuously dilated apically and gently curved ventrad (Fig. 542).
description: Published as part of Lackner, Tomáš, 2010, Review of the Palaearctic genera of Saprininae (Coleoptera: Histeridae), pp. 1-254 in Acta Entomologica Musei Nationalis Pragae (suppl.) (suppl.) 50 on pages 167-171, DOI: 10.5281/zenodo.4272127