Diaulota submarina, Ahn, 2023

Ahn, Kee-Jeong, 2023, Description of Diaulota submarina sp. nov. (Coleoptera: Staphylinidae: Aleocharinae) on Korean coasts, Zootaxa 5336 (1), pp. 141-147 : 141-142

Diaulota submarina sp. nov.

( Figs. 1–4 )

Diaulota uenoi: Ahn, 1996: 284 ; Frank and Ahn, 2011: 26; Ahn et al., 2017: 306; Park and Lee, 2021: 240 [misidentification].

Description. Small, body length 2.5–2.9 mm. Body more or less narrow but robust, long setae densely pubescent ( Fig. 1 ). Body reddish brown with blackish brown abdominal tergites VI–VII. Head slightly deflexed, 1.2 times as long as wide ( Fig. 2A ), sculpture reticulate, about 3 pairs of long filiform setae present on each side, infraorbital carina present ( Fig. 2B ). Antennomeres 4–5 more or less subquadrate, 6–10 transverse. Eye small, 0.2 times as long as head ( Fig. 2A ), minute setae present between facets. Labrum ( Fig. 3A ) large, semicircular, 12 long and macrosetae and 4–5 short and microsetae present on each side of midline. Mandibles ( Fig. 3B ) narrow and elongate, more or less symmetrical, small median tooth present. Maxilla ( Fig. 3C ) with galea and lacinia elongate, almost equal in length; galea corneous, apex and internal surface densely pubescent with long filiform setae; lacinia more or less acute, internal surface with comb of single row of about 8 well separated spines followed by several setae, a distinctive row of several setae present on mesal half of lacinial surface; maxillary palpus with 4 articles, robust, article 3 incrassate distally and longer than article 2, article 4 narrowed distally. Labial palpi ( Fig. 3D ) with 3 distinct articles, palpomere 1 slightly longer than wide, palpomere 2 narrower than 1 and almost 2.0 times as long as 1, palpomere 3 narrower than 2 and slightly longer than 1; ligula simple and elongate with 2 minute setae; twin pores, median pore, and distal pore indistinctly present; medial setae absent on prementum, real pores and setal pores present, basal pores absent, pseudopores absent in very narrow median area, about 4 pseudopores present on each side; a pair of indistinct comb-like hypoglossae present. Mentum ( Fig. 3D ) without v setae, anterior margin shallowly emarginate, several setae present, many punctures present. Submentum with numerous punctures and setae. Neck absent. Pronotum 0.9 times as long as wide, narrowest at base and widest near one third, basal margin almost straight but slightly prolonged posteriorly on median region, apical margin slightly prolonged anteriorly; long setae subparallel, uniformly distributed and apical half directed anteriorly, basal half directed posteriorly in a narrow median strip, others curve correspondingly; about 3 pairs of long filiform setae present, 1 on disc, 1 on lateral margin, and 1 on apico-lateral margin. Hypomeron entirely visible in lateral aspect, with longitudinal carina. Scutellum more or less diamond-shaped. Elytron 1.2 times as long as wide; 0.7 times as long as pronotum; long setae uniformly distributed and directed posteriorly; about 2 pairs of long filiform setae present, 1 on disc and 1 on lateral margin. Hind wings absent. Mesocoxal cavities contiguous; mesoventral process short and pointed ( Fig. 2C ). Metaventrite shorter than width of mesocoxa, expanded apico-basally ( Fig. 2C ). Metendosternite Y-shaped ( Fig. 2C ). Tibiae with two thick setae on hind margin. Tarsal formula 4-4-4, tarsus with long setae but spatulate seta absent. Claws narrow, long, sickle-shaped. Abdomen gradually broadening to rounded apex; relatively long numerous setae uniformly distributed, directed posteriorly. Tergites III–VI strongly impressed at base. Sternites not impressed at base. Male sternite VIII ( Fig. 4A ) prolonged posteriorly as broad triangular projection but female unmodified. Male tergite X slightly truncated at posterior margin ( Fig. 4B ). Female tergite X rounded at posterior margin ( Fig. 4C ). Median lobe with complex internal sclerites ( Fig. 4D ). Paramere ( Fig. 4E ). Spermatheca ( Fig. 4F ).

Specimens Examined. Holotype: 1♁ ( CNUIC), with labels as follows: “ KOREA: Chungnam: Anmyeon Isl., Bangpo Beach , 8 VI 1994, K. J. Ahn, ex rocks in low tide | Holotype Diaulota submarina Ahn, 2023 ” . Paratypes: 7 exx. (4 on slides), same data as holotype; 15 exx., KOREA: Chungnam Prov., Muchangpo , 28 III 1998, K.-J. Ahn, ex inside empty barnacles in low tide . Other specimens: 13 exx. (alcohol collection), Chungnam: Anmyeon Isl., Bangpo Beach , 7 VI 1994, K. J. Ahn, ex rocks in low tide; 10 exx. (alcohol collection, 1 on slide), Jeju Prov., Udomyeon , Yeonpyeong-ri , Udo island , 1 III 2007, KJ Ahn; 1 ex., Gyengnam Prov. , Geoje City, Gabae-ri, 1 VII 2000, K.-J. Ahn, H.-J. Kim M.-J. Jeon, ex barnacles .

Distribution. Korea (South).

Etymology. The adjective submarina refers to the microhabitat of the species.

Remarks. There is sexual dimorphism in size (bigger in male) and shape of head (broadening anteriorly in male but more or less parallel in female) in this new species as other Diaulota species ( Fig. 1A ).

This species is similar to D. uenoi and almost indistinguishable by the external morphological characters (see key couplet below). However, it is different from the latter in mouthparts and the external shape and internal structure of the median lobe. Apical process of D. uenoi is broader and more abruptly bent upward (fig. 10L in Sawada, 1971) compared to the new species, narrower and slightly bent upward ( Fig. 4D ; fig. 40 in Ahn, 1996). Especially, the form of internal sclerites of median lobe are different: apical one larger and polygonal in D. submarina ( Fig. 4D ; fig. 40 in Ahn, 1996) but smaller and rounded in D. uenoi (fig. 10L in Sawada, 1971). They can be regarded as cryptic species.

Figures

FIGUER 1. Habitus of Diaulota submarina sp. nov. A Male B Female. Body length = 2.45 mm.

FIGURE 2. Diaulota submarina sp. nov. A Male head, dorsal aspect; B Male head, ventral aspect; C Meso- and Metaventrites, ventral aspect. Scale bars = 0.1 mm.

FIG. 3. Diaulota submarina sp. nov. A Labrum, dorsal aspect; B Mandibles, ventral aspect; C Maxilla, ventral aspect; D Labium, ventral aspect. Scale bars = 0.1 mm.

FIG. 4. Diaulota submarina sp. nov. A Male sternite VIII, ventral aspect; B Male tergites IX–X, dorsal aspect; C Female tergites IX–X, dorsal aspect; D Median lobe, lateral aspect; E Paramere, lateral aspect; F Spermatheca. Scale bars = 0.1 mm.