Atheta (Alaobia) rigidicornis Lee and Ahn, 2017

Lee, Seung-Gyu & Ahn, Kee-Jeong, 2017, Description of a New Species of Atheta (Alaobia) Thomson, 1858 (Coleoptera: Staphylinidae: Aleocharinae) in Korea, The Coleopterists Bulletin 71 (4), pp. 810-816 : 811-815

Atheta (Alaobia) rigidicornis Lee and Ahn , new species

( Figs. 1–5 )

Type Material. Holotype: Ƌ, labeled as follows: ‘ KOREA: Jeju Prov., Jeju-si, Yeon-dong, Eoseungsaeng reservoir, 20 viii–3 ix 2006, JC Jeong, malaise trap ; HOLOTYPE Atheta (Alaobia) rigidicornis Lee and Ahn 2016 ’. ( CNUIC) . Paratypes: 19 exx. ( CNUIC): 1 ex., same data as holotype; 6 exx., ‘ KOREA: Chungnam Prov., Gongju- City, Mt. Gyeryongsan, Dongwol , N36°19'39.0″ E127°15'46.7″, 1 vi ~ 18 vi 2004, KJ Ahn, SM Choi, JS Park, ex FIT’; 2 exx., same data as former except for ‘ N36°20'27.8″ E127°15'11.5″ ’; 4 exx., same data as former except for ‘Eunseon-waterfall, N36°20'58.7″ E127°12'41.3″, SM Choi, JS Park’; 2 exx., same data as former except for ‘ Nammaetop, N36°21'11.8″ E127°13'20.8″ ’; 2 exx., same data as former except for ‘ N36°22'03.2″ E127°12'50.0″, 31 v ~ 18 vi 2004 ’; 3 exx., same data as former except for ‘ Kapsa’ .

Description. Length 2.2–2.8 mm. Body subparallelsided ( Fig. 1 ); surface fairly glossy, densely pubescent with microsculpture. Body reddish yellow to reddish brown; head and abdominal segments VI–VII almost black; antennomeres 1–3 and legs paler. Head: Slightly transverse ( Fig. 3A ), approximately 1.1–1.2 times as wide as long, widest across eyes, narrower than pronotum; eyes large and prominent, about 1.6–1.8 times as long as temples; gular sutures moderately separated, diverging basally. Antennae ( Fig. 3B ) moderately long and slender, gradually dilated apically; antennomeres 1–3 elongate, 1 longest, 2 slightly longer than 3, 4–10 distinctly transverse, longer than preceding 2 combined and slightly shorter than preceding 3 combined. Mouthparts: Labrum ( Fig. 2A ) transverse, slightly emarginate in anterior margin, with E -sensillum and 8 macrosetae on each side of midline; epipharynx ( Fig. 2B ) with several sensilla, including 2 lateral sensory rows on each side of midline; α- sensillum long and setaceous, about 3.0 times as long as E -sensillum; β- and Ƴ- sensilla short, β- sensillum obtuse at apex, Ƴ- sensillum convergent at apex. Mandibles ( Fig. 2C–D ) asymmetrical, subtriangular, decurved and pointed apically, about 1.4–1.5 times as long as basal width; very few denticles present in molar region; right mandible ( Fig. 2C ) with small internal tooth, internal margin slightly serrulate; prostheca developed. Galea and lacinia of maxilla ( Fig. 2E ) long and slender; lacinia composed of 7 spines in distal comb region, 2 isolated spines present; last spine of distal comb region and isolated spines close together; maxillary palpus elongate and pubescent; palpomere 1 smallest, 2 about 2.7–2.9 times as long as wide, 3 slightly longer than 2, about 2.5–2.7 times as long as wide, 4 digitiform, filamentous sensilla reaching to basal half. Labium ( Fig. 2F ) with ligula divided into 2 lobes in basal half; prementum with 2 medial setae very narrowly separated; 2 basal pores contiguous; few medial pseudopores, several lateral pseudopores, 1 setal pore and 2 real pores present on each side of midline; labial palpus elongate, with many setulae; palpomere 1 largest and dilated basally, about 1.5–1.7 times as long as wide, with Ƴ- setula close to b-seta, 2 shortest, about 1.6–1.8 times 812 as long as wide, 3 narrowly long and about as long as 1, process combined; metaventral process about as long about 4.0 times as long as wide. Mentum ( Fig. 2F ) as or slightly longer than isthmus. Elytra longer and trapezoidal, anterior margin slightly emarginate; wider than pronotum; elytron ( Fig. 3H ) approxiv-seta relatively long, closer to u-seta than w-seta. mately 1.6 times as long as wide, pubescence directed Thorax: Pronotum ( Fig. 3C ) approximately 1.4–1.5 posteriorly and postero-laterally; postero-lateral times as wide as long, widest at basal third to half. margin slightly sinuate; hind wings fully de- Metanotal scutum ( Fig. 3E ) with 1 long seta and veloped, flabellum ( Fig. 3E ) composed of about 4–6 about 3 or 4 short setae on each side of midline. setose lobes. Legs: Slender and long, with dense Mesoventral process ( Fig. 3F ) slightly pointed at pubescence and macrosetae; meso- and metaapex, distinctly longer than isthmus and metaventral tibiae with different lengths of 2 spurs at apex; 814 tarsal formula 4-5-5, length ratio of tarsomeres VIII subtruncate, with long and short marginal setae, 22:23:24:72 (protarsus), 26:32:34:33:75 (meso- minute setae present in median region.

tarsus), 37:40:42:42:86 (metatarsus); 1 empodial seta Distribution. Korea (South).

present, shorter than claw. Abdomen: Subparallel- Remarks. This species is similar to A. scapularis , sided; surface distinctly glossy and densely pu- but it can be distinguished by the male abdominal bescent, with slightly reticulate microsculpture (Fig. tergite VIII with longer processes, the macrochaetal 4B); macrochaetal arrangement of tergites II–VI 01- arrangement of the abdominal tergites, different 02-12-12-13. Aedeagus: Median lobe ( Figs. 4D , shape of the internal sac of the aedeagus, and the 5A–B) narrowly ovate, apical process pointed spermatheca with an elongate umbilicus.

apically in ventral aspect. Apical lobe of paramerites Etymology. Named derived from the Latin ( Fig. 5C ) subparallel-sided, with 4 short setae; d- rigidicornis meaning ‘rigid process’, which is loseta slightly longer than other setae. Spermatheca: cated on male abdominal tergite VIII.

Bursa with elongate umbilicus; duct slender and

recurved, twisted at apex ( Fig. 5D ). Secondary DISCUSSION

sexual characteristics: Male tergite VIII ( Fig. 4A )

with 4 macrosetae on each side of midline, posterior Although Alaobia was proposed as a subgenus of margin with 4 processes; 2 outer processes slender, the genus Atheta by Ganglbauer (1895), it had been pointed at apex, slightly longer than inner processes; treated as a genus by some researchers (Benick and 2 inner processes relatively broad, blunt at apex; Lohse 1974; Sawada 1984). Sawada (1984) noted male sternites V–VI with many small pores; male that it could be distinguished from Atheta by the sternite VIII ( Fig. 4C ) with about 7 macrosetae on following characters: cervical carina not diverged; each side of midline, posterior margin triangular Ƴ- sensillum of epipharynx well developed; ligula convex, with inconspicuous and long marginal se- fusiform. However, we consider that these character tae; posterior margin of female tergite VIII truncate in differences are insufficient to separate the subgenus median region; posterior margin of female sternite as a distinct genus.

The new species is very similar to A. scapularis , including the shape of the median lobe of the aedeagus. However, we recognize them as separate species based on morphological differences provided in the remarks and their geographic distribution. Also, Alaobia is recorded for the first time in East Asia.

Figures

Fig. 1. Habitus of Atheta (Alaobia) rigidicornis, male, 2.5 mm.

Fig. 2. Atheta rigidicornis. A) Labrum, dorsal view, B) Epipharynx, ventral view, C) Right mandible, dorsal view, D) Left mandible, ventral view, E) Left maxilla, ventral view, F) Labium, ventral view.

Fig. 3. Atheta rigidicornis. A) Head, ventral view, B) Antenna, C) Pronotum, dorsal view, D) Prosternum, ventral view, E) Metanotum, dorsal view, F) Meso- and metaventrites, ventral view, G) Scutellum, dorsal view, H) Elytron, dorsal view.

Fig. 4. Atheta rigidicornis. A) Male abdominal tergite VIII, dorsal view, B) Microsculpture of male abdominal tergite VIII, dorsal view, C) Male abdominal sternite VIII, ventral view, D) Median lobe of aedeagus, lateral view.

Fig. 5. Atheta rigidicornis. A) Median lobe of aedeagus, lateral view, B) Median lobe of aedeagus, ventral view, C) Paramere, lateral view, D) Spermatheca. Scale bars = 0.1 mm.