Carinaulus (Tesař, 1945) Tesař (1945): 66. Type species: Aphodius vseteckai Tesař, 1945 = Carinaulus vseteckai (Tesař, 1945). Elevated to genus by Dellacasa et al. (2001): 113.

Aphodius (Carinaulus) Tesař, 1945 Tesař (1945): 66. Type species: Aphodius vseteckai Tesař, 1945 = Carinaulus vseteckai (Tesař, 1945).

Aphodius (Oxyaphodius) Balthasar, 1965 Balthasar (1965): 314. Type species: Aphodius (Oxyaphodius) sikkimensis Balthasar, 1965 = Carinaulus sikkimensis (Balthasar, 1965). syn. by Červenka (2000): 30.

The members of the genus Carinaulus can be distinguished from other Aphodiinae taxa by the following combination of characteristics [modified from Červenka (2000) and Dellacasa et al. (2001)]: clypeus wide, margin weakly to moderately concave at the middle; with or without cephalic tubercles (occasionally in sexual diamorphism); elytral striae wide and deep, strial puncture distinctly crenulated; intervals tectiform or carinate; sixth and eighth intervals joined before pre-apical area; carina generally lacking in apical area of elytral intervals; meso- and metatibia apical spinules more or less equal in length, exceptionally unequal in length.

Aphodius (Agrilinus) inexspectatus Balthasar, 1935 [original spelling] Balthasar (1935): 121. — spelling later corrected to inexpectatus by subsequent authors. comb. in Carinaulus by Červenka (2000): 44.

Aphodius (Carinaulus) nigrocarinatus Nikolajev, 1979 Nikolajev (1979): 99. syn. by Stebnicka and Galante (1991): 727.

Aphodius (Carinaulus) coreensis Kim, 1986 Kim (1986): 8. syn. nov.

Records from the Korean Peninsula

Agrilinus inexpectatus: Minkina (2022): 237 (North Korea).

Aphodius (Agrilinus) inexpectatus: Stebnicka (1980): 243 (North Korea); Stebnicka and Galante (1991): 727 (North Korea).

Aphodius (Agrilinus) inexspectatus: Kim (1989): 4 (North Korea); Kim (2000): 100 (North Korea); ESK and KSAE (1994): 148 (North Korea) [Korean Checklist].

Aphodius (Carinaulus) coreensis: Kim (1986): 8 (South Korea); Kim (2000): 87 (South Korea); Dellacasa and Dellacasa (2006): 117 (North and South Korea) [Palaearctic Catalogue]; Kim (2012): 108 (South Korea); KSAE and ESK (2021): 262 (South Korea) [Korean Checklist].

Aphodius (Carinaulus) inexspectatus: Dellacasa and Dellacasa (2006): 117 (North Korea) [Palaearctic Catalogue]; Kim (2012): 109 (North Korea); KSAE and ESK (2021): 262 (North Korea) [Korean Checklist].

Carinaulus coreensis: Dellacasa et al. (2016): 116 (South Korea) [Palaearctic Catalogue].

Carinaulus inexpectatus: Dellacasa et al. (2016): 116 (North and South Korea) [Palaearctic Catalogue].

Total body length: 5.1−6.7 mm. Medium to large-sized beetles.

Colouration (Fig. 1A; Fig. 2A; Fig. 3A): Body colour reddish-brown to brown, surface shiny. Antenna lamellate colour yellowish.

Male (Fig. 3A): Body elongate oval shape.

Head (Fig. 4A): Clypeal margin rim distinct and thin, somewhat distinctly reflexed; clypeus moderately bordered, anterior margin weakly concave at the middle, its lateral apex area widely arcuate, antero-lateral margin nearly transverse. Genae rather strongly protruded laterally, lateral margin arcuate, slightly exceeding eyes; dorsal surface punctation structure similar with frontal ones; apex of lateral margin rim with seven to ten rather long setae (in dorsal view). Clypeal suture rather feeble (discernible); anterior margin rim nearly transverse, but distinctly soared at the distal area of clypeal suture. Frontoclypeal suture nearly transverse, rather distinctly marked. Epistoma medial area weakly convex; clypeal surface distinctly microreticulated, rather densely punctate and its punctures denser and larger to laterally; Surface below the frontoclypeal suture with three protuberances, medial protuberance distinctly soared, lateral protuberances moderately soared. Frontal area with fine punctures, moderately to rather densely distributed; medial area surface smooth, without punctuation, and slightly pressed.

Epipharynx (Fig. 4C and D): Anterior margin slightly convex medially; lateral angles rounded; lateral margins moderately narrowed posteriorly. Epitorma-tylus structure rounded-triangular, slightly exceeding anterior margin of epipharynx; tylus area with two distinct lengths of celtes, closely grouped: one to two long celtes basally; three to five short celtes apically (median region). Epitorma anterolateral area with numerous heli. Acropariae with homogenous chaetae, moderately dense. Acanthopariae chaetae distinctly shorter than acropariae chaetae, becoming sparser posteriorly. Prophobae with microsetae moderately dense, denser proximally; chaetopedia moderately distributed in three to four irregular rows. Chaetopariae with dense row of stout spinules, slightly longer, but thinner than chaetopedia. Apophobae with a few rows of microsetae, moderately distributed along chaetopariae. Dexiotorma slightly longer than laeotorma.

Pronotum (Fig. 3A and B): Pronotum disc sub-rectangular (Fig. 3A), widest in posterior 1/3 area to posterior angle; pronotum maximum width very slightly narrower than that of the elytra. Pronotum margin rim distinct, moderately thick in lateral margin (Fig. 3B), very thin in posterior margin; anterior margin nearly transverse in dorsal view; anterior angle more weakly protruded than anterior margin; lateral margin very weakly arcuate; posterior angle widely round; posterior margin weakly sinuate, slightly convex at the middle, along the margin rim with very narrow and shallow furrow. Dorsal surface with two different-sized punctures; rather densely punctate, larger punctures 3x to 4x larger than fine punctures; punctures sparsely in medial area, denser to laterad.

Scutellum (Fig. 1A; Fig. 3A): Small and triangular; surface microreticulated; surface with few shallow irregular-shaped punctures distributed moderately.

Elytra (Fig. 3A and B): Moderately convex (Fig. 3A), very slightly widened posteriorly; without humeral teeth; with clearly visible ten striae intervals; most striae joined or shortened before apex. Striae very distinct and somewhat wide and deep; strial punctures very densely punctate, its moderately indenting margin of intervals at the anterior half; strial punctures distinctly larger than micropunctures of intervals. 1^st and 10^th striae mostly joined at the apical; remaining striae generally not joined, nearly confluent near the base (especially 9^th and 10^th striae); 4^th and 5^th, 7^th to 9^th striae occasionally joined; [Second joining] (7^th+8^th) and 9^th striae occasionally joined. 6^th to 8^th striae shortened before basis, 6^th stria slightly longer than 7^th stria at the basis (Fig. 3B); 8^th stria starting from anterior 2/7 area of elytra. Intervals surface weakly microreticulated; central area somewhat distinctly convex (carinate), especially in posterior area, intervals lateral border rather flattened; micropunctures moderately punctate, forming three to five rows in intervals. Elytral margins border very adjacent with 10^th stria.

Legs (Fig. 1A; Fig. 3A and C): Meso- and metatrochanter with two to three rather long setae at the ventral ridges. Femora surface microreticulated and punctate finely and moderately distributed; profemoral ventral surface punctures larger than meso- and metafermoral ones, antero-ventral ridge with two rows of somewhat densely distributed long setae; ventral surface of mesofemora anterior area with three to five large setigerous punctures, medio-apical area with a row of two to three setigerous punctures and its setae long and stout (Fig. 3C). Protibiae (Fig. 3A) anterior area surface smooth; outer margin tridentate, remaining area with two to three fine teeth (smaller to proximally); apical spurs very slightly curved downwardly and apex relatively sharp, not reaching half of 2^nd protarsomere. Meso- and metatibiae with two strong transverse carinae; bristle of spinules rather long and two different lengths in carinae (occasionally subequal lengths); most apical rim spinules variable in length, usually two to three size classes, generally subeqaul; variation also within an individual, differences possibly due to abrasion, especially on the metatibial rim. Metatibiae superior apical spur as long as 1^st metatarsomere; inferior apical spur shorter than 1^st metatarsomere. 1^st metataromere (= basimetatarsomere) slightly longer than next two combined (Fig. 1A; Fig. 3A). Claws rather fine, regularly, arcuate.

Venter (Fig. 3C): Mesosternum with medial surface microreticulated; coarse, irregular punctures sparser medially, denser laterally; medial area with numerous very thin vertical furrows. Metasternum very shiny; medial area slightly elevated, surface weakly concave; with a thin vertical furrow medially; micropunctures moderately to rather densely distributed. Abdominal sternites weakly shiny, with distinct microreticulation; setigerous punctures rather densely distributed; setae of two distinct lengths, longer setae present on the medio-lateral areas of ventrites. Pygidium similar in structure to abdominal sternites; with six to eight long setae on the medial area; posterior margin with moderately dense, medium-length setae.

Aedeagus (Fig. 5): Parameres symmetrical and simple shape (Fig. 5A); phallobase slightly longer than parameres length. Parameres slightly curved downwardly; gently narrowed anteriorly; ventral surface microgranulate (Fig. 5C); ventral area slightly concave at the basal 1/4 area (Fig. 5B); apex round and microgranulated (Fig. 5D).

Female (sexual diamorphism) (Fig. 2A, B; Fig. 4B). Similar to male, with the following differences.

Head (Fig. 4B): Frontoclypeal central protuberance less protruded than male. Head dorsal surface punctation slightly denser than male.

Pronotum (Fig. 2A, B): Pronotum dorsal punctation denser than male. Pronotum less convex than male.

Venter: Metasternum medial soared area, its surface nearly flattened.

Korea (South, North), Russia (Far East) (Fig. 6).

Carinaulus coreensis (Kim, 1986) was originally described, based on the holotype, allotype and 13 paratypes (Kim 1986). Examination of the designated type repository, the Sungshin Women’s University Insect Collection (SWUIC, Seoul), revealed that the holotype and majority of paratypes are not currently traceable. However, two female paratypes (Fig. 2) and one additional voucher specimen were recovered from the collection of the NIBR (Incheon). Additionally, one male and one female voucher specimen, identified by Kim, were located in the NASIC (Wanju). For comparative analyses, photographs of the holotype of C. inexpectatus (Balthasar, 1935), housed in the Czech National Museum (Prague), were examined (Fig. 1). Three additional male specimens collected from Mt. Geumgang, North Korea and housed in NIBR were also studied. These served as reference material for evaluating the taxonomic status of C. coreensis. See the discussion below for the justification of the synonymy.