Review of the species of Stenothemus from Southeast China (Coleoptera, Cantharidae)

The species of Stenothemus Bourgeois, 1907 from Southeast China are reviewed. Stenothemus fukienensis Wittmer, 1974 and S. kuatunensis Wittmer, 1979 are supplementarily described. Two new species are described, S. longicornis Y. Yang & H. Liu sp. nov. (China: Guangdong) and S.  flavus Y. Yang & X. Yang sp. nov. (China: Zhejiang). Five new combinations are established: S. biimpressiceps (Pic, 1930) comb. nov. (from Cantharis L.), S. chinensis (Wittmer, 1982) comb. nov., S. limbatipennis (Pic, 1926) stat. rev. et comb. nov., S. nigriceps (Wittmer, 1955) comb. nov. and S. pallicolor (Wittmer, 1951) comb. nov. (from Lycocerus Gorham). Leiothorax atrosanguineus Švihla, 2005 syn. nov. is synonymized with S. chinensis, Lycocerus limatus Kazantsev, 2007 syn. nov. with S. limbatipennis. The above species are illustrated with habitus photos, aedeagi, abdominal sternites VIII and internal genitalia of female. A key for the identification of the above species is provided.

ABDOMINAL STERNITE VIII (Fig. 8A). Obliquely narrowed posteriorly, latero-apical angles obtusely rectangular, posterior margin deeply and roundly emarginate in middle and feebly sinuate on both sides, behind notch with membrane which presents small longitudinal sclerite at center. (Fig. 6A). Vagina stout, with median oviduct situated at ventroapical part, diverticulum and spermathecal duct arising from apex; diverticulum moderately long, about 0.12 times body length, evenly thinned apically, slender tube-shaped and spiral; spermathecal duct much shorter than diverticulum; spermatheca slender tube-shaped and spiral, obviously thinner than spermathecal duct and slightly longer than diverticulum, with basal part extended into short tube, where accessory gland opening. Accessory gland thin and obviously shorter than spermatheca.

Remarks
This species was originally described based on a single female type (Pic 1930). During our study, the type was located at MNHN, as well as some additional specimens, making it possible for us to study this species in detail. The morphological characters, especially the structure of the aedeagus, show that it belongs to Stenothemus and not to Cantharis.

Stenothemus pallicolor
HEAD. Subquadrate, surface sparsely and fi nely punctate, each side with smooth and rectangular impression behind antennal socket; eyes strongly protruding, head width across eyes 1.2 times as wide as pronotum; terminal maxillary palpomeres long-triangular, widest in basal third; antennae fi liform, extending to two-thirds length of elytra; antennomere II about twice as long as wide at apices, III about 2.5 times as long as II, IV longest, XI slightly longer than X, pointed at apex.
PRONOTUM. Subquadrate, about 1.1 times as long as wide, anterior margin nearly straight, anterior angles roundly truncate, lateral margins slightly sinuate, posterior margin straight and narrowly bordered, posterior angles nearly rectangular and slightly protruding, disc distinctly convex on posterolateral parts, surface fi nely and sparsely punctate.
ELYTRA. Slightly dilated posteriorly, about 4.3 times as long as humeral width, 6.0 times as long as pronotum, surface densely and fi nely punctate, present with hardly visible longitudinal costae. AEDEAGUS ( Fig. 3D-F). Strongly swollen dorsally at basal part, nearly parallel-sided in apical part; basal piece obviously as long as dorsal plate of each paramere, with a large, bifurcate conjoint middle nodule at base of ventral side; ventral process of each paramere nearly parallel to each another, long and slightly thickened apically, bent dorsally in lateral view; dorsal plate nearly as long as ventral process, strongly narrowed and even in width along the whole length, acute at apex and folded ventrally; apical parts of laterophyses depressed and separate from each other, apex acute and almost reaching middle emargination between dorsal plates.

Female
Similar to male, but body stouter, eyes less protruding, head width across eyes slightly wider than anterior margin of pronotum; antennae shorter, extending to elytral mid-length; elytra about 4.0 times as long as humeral width. ABDOMINAL STERNITE VIII (Fig. 8B). Strongly narrowed posteriorly, latero-apical angles obtusely widetriangular, posterior margin deeply and rectangularly emarginate in middle and hardly emarginate on both sides, behind notch with membrane which presents small traverse-triangular sclerite at center. (Fig. 6B).Vagina stout, with median oviduct situated at ventroapical part, diverticulum and spermathecal duct arising from apex; diverticulum moderately long, about 0.12 times body length, evenly thinned apically, slender tube-shaped and spiral; spermathecal duct long but shorter than diverticulum; spermatheca slender tube-shaped and spiral, slightly thinner than spermathecal duct and shorter than diverticulum, with basal part extended into short tube, where accessory gland opening. Accessory gland thin, and shorter than spermatheca.

Remarks
The morphological characters, including the aedeagus, indicate that this species should belong to Stenothemus.

Stenothemus limbatipennis
HEAD. Subquadrate, surface densely and fi nely punctate, each side with smooth rectangular impression behind antennal socket; eyes moderately protruding, head width across eyes 1.3 times as wide as pronotum; terminal maxillary palpomeres long-triangular, widest in middle; antennae fi liform, extending to two-thirds length of elytra, antennomere II about twice as long as wide at apices, III about 2.5 times as long as II, IV-XI each with smooth longitudinal impression in middle of outer edge, VI longest, XI slightly longer than X, pointed at apex.
PRONOTUM. Subquadrate, about 1.1 times as long as wide, anterior margin slightly arcuate, anterior angles obtuse, subrounded, lateral margins nearly parallel and slightly sinuate, posterior margin straight, posterior angles moderately sharp and protruding, disc strongly convex on posterolateral parts, surface lustrous, fi nely and densely punctate.
ELYTRA. Parallel-sided, about 3.4 times as long as humeral width, 4.8 times as long as pronotum, humeral lustrous, the rest of surface densely and fi nely punctuate, with hardly indicated longitudinal costae.

AEDEAGUS (Fig. 3G-I).
Moderately swollen laterally at basal part, shrunk apically in diameter; basal piece nearly as long as dorsal plate of each paramere, with a moderately large, bifurcate conjoint of? middle nodule at base of ventral side; ventral process of each paramere approaching to each other, short and slightly narrowed apically, bent ventrally in lateral view; dorsal plate slightly longer than ventral process, abruptly narrowed near base and bent to each other, apex acute and directing ventrally; apical part of laterophyses depressed and separated far from each other, apex acute and reaching middle emargination between dorsal plates.

Female
Similar to male, but more robust, eyes smaller, slightly protruding, antennae thinner and shorter, roughly extending to elytral mid-length, IV-XI without smooth longitudinal impressions; pronotum slightly wider.
ABDOMINAL STERNITE VIII (Fig. 8C). Strongly narrowed posteriorly, latero-apical angles widely rounded, posterior margin widely and roundly emarginate in middle and feebly sinuate on both sides, behind notch with membrane which is weakly sclerotised and tapered at apex. (Fig. 6C). Vagina elongate, with median oviduct situated at ventro-apical part, diverticulum and spermathecal duct arising from apex; diverticulum relatively short, about 0.08 times body length, evenly thinned apically, slender tube-shaped and spiral; spermathecal duct moderately long but obviously shorter than diverticulum; spermatheca slender tube-shaped and spiral, obviously thinner than spermathecal duct and extremely long, much longer than diverticulum, basal part extended into a moderately long tube, where accessory gland opening. Accessory gland moderately thin and shorter than spermatheca.

Variation
Head sometimes orange at vertex, pronotum more or less darkened at anterior part or both sides, elytra light yellow at more or less parts of margins.

Remarks
The type was not located in MNHN although we tried several times; several specimens with labels written by Dr W. Wittmer with the specifi c name were found in NHMB. According to the previous work done by Wittmer (1969Wittmer ( , 1972, it is speculated that he had examined the types during his working period, so the specimens determined by him are our references for the identifi cation. Kazantsev (2007) introduced the new name Lycocerus limatus for L. limbatipennis (Pic, 1926) (originally in Podabrus), which was preoccupied by Lycocerus limbatipennis (Pic, 1906) (Pic, 1926) (ICZN Article 59.4).

Stenothemus nigriceps
HEAD. Subquadrate, surface densely and fi nely punctuate, each side with smooth rectangular impression behind antennal socket; eyes strongly protruding, head width across eyes about 1.2 times as wide as pronotum; terminal maxillary palpomeres long-triangular, widest in middle; antennae fi liform, extending to two-thirds length of elytra; antennomeres II about 2.5 times as long as wide at apices, III about twice as long as II, IV longest, XI slightly longer than X, pointed at apex. PRONOTUM. Subquadrate, about 1.2 times as long as wide, anterior margin nearly arcuate, anterior angles widely rounded, lateral margins nearly parallel, posterior margin straight, posterior angles moderately sharp, protruding, disc distinctly convex on posterolateral parts, surface fi nely and densely punctate.
ELYTRA. Parallel-sided, about 4.0 times as long as humeral width, 4.2 times as long as pronotum, surface densely and fi nely punctate, with hardly indicated longitudinal costae. AEDEAGUS (Fig. 4A-C). Weakly swollen dorsally in basal part, weakly contracted in diameter basally; basal piece obviously shorter than dorsal plate of each paramere, each with triangular protuberance but without conjoint middle nodule at base of ventral side; ventral processes of parameres approaching to each other, long and slightly widened at apices, bent dorsally in lateral view; dorsal plate slightly longer than ventral process, strongly narrowed apically, narrow-triangularly protuberant in middle, apex acute and approaching to each other; apical part of laterophyses compressed and next to each other in middle, apex hooked and directed laterally, slightly exceeding middle emargination between dorsal plates.

Female
Similar to male, but body stouter, eyes less protruding, head width across eyes slightly wider than anterior margin of pronotum; antennae narrower and shorter, extending to elytral mid-length; pronotum wider, nearly as long as wide; elytra slightly dilated posteriorly, about 3.1 times as long as humeral width.
ABDOMINAL STERNITE VIII (Fig. 8D). Obliquely narrowed posteriorly, latero-apical angles widely triangular, posterior margin deeply and roundly emarginate in middle and nearly straight on both sides (membrane missing behind notch). (Fig. 6D). Vagina moderately elongate, with median oviduct situated at ventro-apical part, diverticulum and spermathecal duct arising from apex; diverticulum moderately long, about 0.16 times body length, evenly thinned apically, slender tube-shaped and spiral; spermathecal duct much shorter than diverticulum; spermatheca slender tube-shaped and spiral, obviously thinner than spermathecal duct and shorter than diverticulum, with basal part extended into short tube, where accessory gland opening. Accessory gland thin and shorter than spermatheca.

Remarks
In this study, the structure of abdominal sternite VIII of the female is incomplete. Because there is only one female specimen, the structural description of abdominal sternite VIII needs to be improved.

Remarks
Furthermore, the holotype male of Leiothorax atrosanguineus shows that it has no differences from S. chinensis comb. nov.; also, a large series of additional material from several localities is available for examination though their type localities are far away. Therefore, L. atrosanguineus is considered to be a junior synonym of S. chinensis.

Differential diagnosis
The new species is related to S. melleus Švihla, 2005 (located in Sichuan, China), but can be distinguished by its larger body (no more than 9.0 mm length in the latter); femur orange, darkened only at base (in the latter, darkened at least at apical third part); aedeagus: middle emargination between dorsal plates deep, nearly as long as half its length (shallow in the latter, much shorter than half length).

Etymology
The specifi c name is derived from the Latin 'fl avus', meaning 'golden-yellow' and referring to its body coloration.
Male (Fig. 2B) COLORATION. Body yellow, head and prothorax testaceous, pronotum orange at anterior angles, mouthparts, antennae, tarsi, tibiae and bases of femora black brown. Body densely mixed with short recumbent and slightly longer semi-erect light yellow pubescence.
HEAD. Subquadrate, surface sparsely and fi nely punctate, each side with smooth and rectangular impression behind antennal socket; eyes strongly protruding, head width across eyes 1.2 times as wide as pronotum; terminal maxillary palpomeres long-triangular, widest at basal third; antennae fi liform, extending to two-thirds length of elytra, antennomere II about 2.3 times as long as wide at apices, III about 1.7 times as long as II, IV longest, XI slightly longer than X, pointed at apex.
PRONOTUM. Subquadrate, about 1.1 times as long as wide, anterior margin nearly straight, anterior angles roundly truncate, lateral margins slightly sinuate, posterior margin slightly sinuate, posterior angles moderately sharp and protruding, disc strongly convex on posterolateral parts, surface fi nely and densely punctate.
ELYTRA. Moderately dilated posteriorly, about 3.6 times as long as humeral width, 5.1 times as long as pronotum, surface densely and fi nely punctate, with hardly indicated longitudinal costae. AEDEAGUS (Fig. 4D-F). Strongly swollen dorsally at basal part, nearly parallel-sided in apical part; basal piece nearly as long as dorsal plate of each paramere, with a large, bifurcate conjoint middle nodule at base of ventral side; ventral processes of parameres nearly parallel to each other, short and slightly narrowed apically, bent dorsally in lateral view; dorsal plate slightly longer than ventral process, abruptly narrowed in middle, near to each other at basal part, acute at apex and folded ventrally; apical part of laterophyses depressed and separate from one another, apex acute and not reaching middle emargination between dorsal plates.

Female
Similar to male, but stouter, eyes less protruding; antennae shorter, reaching elytral mid-length, pronotum wider, nearly as wide as long.
ABDOMINAL STERNITE VIII (Fig. 8E). Moderately narrowed posteriorly, latero-apical angles widely rounded, posterior margin widely and rectangularly emarginate in middle and truncate on both sides, behind notch with membrane which sclerotised and triangularly bilobed at apex and present with traverse-triangular sclerite at center and small rounded sclerite on each side. (Fig. 7A). Vagina stout, with median oviduct situated at ventroapical part, diverticulum and spermathecal duct arising from apex; diverticulum moderately long, about 0.16 times body length, evenly thinned apically, slender tube-shaped and spiral; spermathecal duct longer than diverticulum; spermatheca slender tube-shaped and spiral, obviously thinner than spermathecal duct and much longer than diverticulum, with basal part extended into short tube, where accessory gland opening. Accessory gland thin and much shorter than spermatheca.

Differential diagnosis
The new species resembles S. hajeki Švihla, 2011 (from N Yunnan, China), but differs in the following characters: antennae without impressions on middle antennomeres (with small oval impressions on antennomeres IV-XI in the latter), pronotum obviously longer than wide (nearly as long as wide in the latter); elytra more elongate, about 3.5 times humeral width (3.2 times in the latter); aedeagus: parameres approaching each other (far from each other in the latter).

Etymology
The specifi c name is derived from the Latin 'longus', meaning 'long', and 'cornus', meaning 'horn', and referring to its long antennae. COLORATION. Body black, mouthparts light brown, reddish brown at apices of mandibles, more or less darkened at maxillary and labial palpi, prothorax reddish brown, femora light brown at basal. Body densely covered with short, recumbent yellow pubescence.

Holotype
HEAD. Subquadrate, surface densely and fi nely punctate, each side with smooth and rectangular impression behind antennal socket; eyes strongly protruding, head width across eyes about 1.4 times as wide as pronotum; terminal maxillary palpomeres long-triangular, widest at basal two-thirds; antennae quite long, obviously exceeding apices of elytra; antennomeres II slightly longer than wide at apices, III about 2.6 times as long as II, III-XI fl attened and subparallel-sided, IV widest, V to XI gradually narrowing towards apex, VIII longest, XI slightly longer than X, pointed at apex.
PRONOTUM. Subquadrate, about 1.2 times as long as wide, anterior margin rounded, anterior angles obtuse, subrounded, lateral margins nearly parallel and slightly sinuate, posterior margin straight and fi nely bordered, posterior angles obtusely rectangular, disc strongly convex on posterolateral parts, surface fi nely and densely punctate.
ELYTRA. Parallel-sided, about 3.5 times as long as humeral width, 4.8 times as long as pronotum, surface densely and fi nely punctate, with hardly visible longitudinal costae. AEDEAGUS (Fig. 4G-I). Moderately swollen laterally at basal part, strongly contracted in diameter apically; basal piece nearly as long as dorsal plate of each paramere, with a large, bifurcate conjoint middle nodule at base of ventral side; ventral processes of parameres approaching each other, short and slightly thickened apically, bent ventrally in lateral view; dorsal plate slightly longer than ventral process, strongly narrowed near base, approaching to each other, apex acute and directed ventrally; apical part of laterophyses separate from each other, apex wide-triangular and bent dorsally, feebly exceeding middle emargination between dorsal plates.

Female
Unknown.

Supplementary description
Male AEDEAGUS ( Fig. 5A-C). Strongly swollen laterally in basal part, contracted in diameter apically; basal piece nearly as long as dorsal plate of each paramere, with a large, bifurcate conjoint middle nodule at base of ventral side; ventral processes of parameres nearly parallel to one another, distinctly thickened apically, bent dorsally in lateral view; dorsal plate slightly longer than ventral process, abruptly narrowed in middle and wide-triangularly protuberant at apical part, near to each other at basal part, apex acute and folded ventrally; apical parts of laterophyses depressed and separate from each other, apex acute and bent dorsally, reaching middle emargination between dorsal plates.

Female
ABDOMINAL STERNITE VIII (Fig. 8F). Moderately narrowed posteriorly, posterior margin deeply and triangularly emarginate in middle and feebly emarginate on both sides; behind notch with membrane, narrowly bilobed at apex and present with longitudinal sclerite at center. (Fig. 7B). Vagina stout, with median oviduct situated at ventroapical part, diverticulum and spermathecal duct arising from apex; diverticulum extremely long, about 0.33 times body length, evenly thinned apically, slender tube-shaped and spiral; spermathecal duct much shorter than diverticulum; spermatheca slender tube-shaped and spiral, obviously thinner than spermathecal duct and nearly as long as diverticulum, with basal part extended into short tube, where accessory gland opening. Accessory gland thin and nearly as long as spermatheca.

Distribution
China (Zhejiang, Fujian). Wittmer, 1979 Fig  Fig. 5D-F). Strongly swollen dorsally in basal part, contracted in diameter basally; basal piece obviously shorter than dorsal plate of each paramere, with a large, bifurcate conjoint middle nodule at base of ventral side; ventral process of each paramere nearly parallel to one another, long and fl attened, apex rounded; dorsal plate slightly shorter than ventral process, nearly parallel-sided, layered in middle, external layer roundly emarginate in middle, internal layer feebly emarginate, apex subrounded; apical parts of laterophyses compressed and next to each other in middle, apex rounded and obviously exceeding middle emargination between dorsal plates.

Remarks
In the original publication (Wittmer 1979), the aedeagus of this species was illustrated only in ventral view; here, it is also illustrated in dorsal and lateral views.