Pterostichus Koreonialoe Park & Kwon, 1996

Yin, Wen-Qi, Shi, Hong-Liang & Liang, Hong-Bin, 2021, Revision of the Chinese species of subgenus Koreonialoe (Coleoptera: Carabidae: Pterostichus), with descriptions of two new species, ZooKeys 1063, pp. 1-21 : 1

Subgenus Pterostichus Koreonialoe Park & Kwon, 1996

Pterostichus Koreonialoe Park & Kwon, 1996: 93. Type species: Pterostichus teretis Park & Kwon, by original designation. Park and Park 2013: 66. Bousquet 2017: 717.

Pterostichus Natalianoe Berlov & Plutenko, 1997: 4. Type species: Pterostichus microps Heyden, by original designation. Sundukov 2013: 130 (as junior synonym of Pterostichus Koreonialoe ).

Pterostichus opacipennis " Pterostichus opacipennis species-group" of Pterostichus Nialoe : Nemoto 1988: 39. Sasakawa et al. 2008: 174. Sasakawa et al. 2013: 430.

Diagnosis.

Medium to large-sized Pterostichus ; head large and thick, with elongate mandibles; eyes small, temporae swollen, a little wider than width across outer margins of eyes; pronotum cordate with posterior angles nearly rectangular; elytra entirely opaque; sternite VI or VII of males without secondary sexual modification.

Comparison.

Pterostichus Koreonialoe species all share two external morphological features not found in other Pterostichus Nialoe species (= Pterostichus Nialoe sensu lato: Kasahara 1988; Sasakawa 2005a): elytra entirely opaque from dense, isodiametric microsculpture; males without secondary sexual modification of sternite VII. Pterostichus Koreonialoe is considered to be a clade sister to the Pterositchus macrogenys species group ( Sasakawa 2005b). These two groups are similar in their enlarged head with elongate mandibles and swollen temporae. But the latter group differs in the dorsal surface of elytra shiny and sternite VII of males is more or less concave.

Subgeneric characters.

Body robust, medium to large size, body length 12-25 mm, elongate and macrocephalic. Dorsally black, dark brown or reddish brown; pronotum finely punctate, more or less opaque; elytra entirely opaque, without metallic luster. Palpi and tarsi brown, other parts of legs similar color as elytra. Head large and thick; eyes small and convex, tempora strongly swollen, generally a little longer than length of eyes; frons with shallow and sparse punctures throughout; frontal grooves shallow and wide, reaching midpoint of eyes. First antennomere shorter than combined length of following two segments. Mandibles long, outer surface nearly straight, apex hooked; apical margin of labrum and clypeus deeply emarginate; terminal segment of labial palpus fusiform, a little dilated in males; mentum tooth bifid, mentum with a pair of longitudinal depressions, submentum with two setae on each side. Pronotum strongly cordate, widest near anterior third, one-sixth to one-fifth wider than length. Surface more or less opaque, with fine punctures, sub-anterior transversal sulci well defined, strongly curved. Lateral margins slightly arched from anterior angles to the middle, strongly sinuate and then nearly straight before posterior angles; posterior angles nearly rectangular; posterior margin strongly emarginate at middle. Mid-lateral setae present near anterior fifth of lateral margins; lateral expansions narrow, equally wide at anterior and posterior portions. Basal foveae with inner and outer grooves faintly defined and partly fused, forming deep depression between them; outer groove slightly shorter than inner one (definition of pronotal inner and outer grooved see Shi et al. 2013: 103); middle area between two basal foveae with strong transverse wrinkles or heavy punctures. Elytra entirely opaque, length a little greater than one-half of width, widest a little behind middle. Shoulders widely rounded; basal ridge and lateral margins forming obtuse angle; striae regular, parascutellar dorsal pore present on the end of first stria; two or three discal pores on third interval, all adjoining to second stria. Umbilicate series on ninth interval continuous, sparse at middle. Ventral side: metepisternum slightly shorter than basal width, nearly smooth; stermite VII with one seta on each side in males, with two in female, male sternite VI or VII without secondary sexual modification. Mesofemora with two setae; metacoxae with two setae; metatrochanters without setae; fifth tarsomere glabrous or setose ventrally. Male genitalia with median lobe of aedeagus stout, curved at basal one-third to one-fourth; right paramere short and straight. Endophallus straight or directed ventrally, with two or more lobes at anterior part. Female genitalia: Gonocoxite II of ovipositor falciform in ventral view, length ca. three times basal width; outer margin with two or three short and fine ensiform setae irregularly arranged, inner margin without ensiform setae; apex strongly compressed, rounded in lateral view, with two nematiform setae in a groove (Figs 28-31 ). Spermatheca with seminal canal and receptaculum differentiated, receptaculum digitate, shortly branched at base, seminal canal much slenderer than receptaculum, three to five times length of receptaculum; spermathecal gland inserted on the base of receptaculum (Figs 32-35 ).

Distribution.

A total of 18 species distributed along the Korean Peninsula and adjacent areas, including the eastern part of Jilin and Liaoning (China), Primorskiy Kray (Russia), Tsushima Island (Japan).

Remarks.

Different species of the subgenus Pterostichus Koreonialoe are extremely similar in their external appearances. All known species are almost indistinguishable from each other by external characters, and even difficult to differentiate by the sclerotized part of male genitalia. Thus previous species delimitation under this subgenus was mainly based on the male endophallic characters, especially the number, location, and shape of apical lobes ( Nemoto 1988; Park and Kwon 1996; Sasakawa et al. 2008).

The endophallus of male genitalia is also important for inferring phylogeny ( Sasakawa 2005a). Previous studies showed that most species (11 of 14) in Pterostichus Koreonialoe have their endophallus short and straight, but the remaining three species ( P. bellatrix , P. syleus , and P. togyusanus ) have the endophallus more elongate and clearly directed ventrally ( Sasakawa et al. 2013). In the present study, we found that the ventrally directed and elongate endophallus present in all four species distributed in China, as well as in P. microps which was not treated by Sasakawa et al. (2013).

To better interpret the infra-subgeneric taxonomy of Pterostichus Koreonialoe , names of two groups are introduced: 1) the Pterostichus opacipennis group (sensu stricto, nec. Nemoto 1988): containing twelve species distributed in the Korean Peninsula and Tsushima, with a short and straight endophallus, gonopore that opens apically to the aedeagus, the ostium very weakly turn left. 2) the Pterostichus microps group: containing six species in Northeast China, the Korean Peninsula, and Primorskiy Kray, with elongate and ventrally directed endophallus, gonopore that opens basally to the aedeagus, aedeagal apex more or less deflected ventrally, the ostium more evidently turned left. Although these two groups included in the subgenus Pterostichus Koreonialoe are not based on a phylogenetic analysis, it seems likely that the Pterostichus opacipennis group (sensu strict) could be monophyletic for their highly specialized endophallus.

The determination of female specimens of Pterostichus Koreonialoe is very difficult sometimes. In most subgenera of Pterostichus , sibling species usually can be differentiated by the outline of pronotum, pronotal basal foveal characters, including the punctuation, length and depth of basal foveal grooves, chaetotaxy on elytra and legs, elytral striae depth and punctation, microsculpture, and male modification on the sternum. But in Pterostichus Koreonialoe , these important characters are always identical for most species. Moreover, the female ovipositor and reproductive tracts also do not help in species determination (Figs 28-35 ). In a few cases, the body size and color are helpful, for example in the two sympatric species P. micropoides and P. bellatrix , the latter one is always much larger and darker in color. But many allopatric species are usually extremely similar to each other. In these cases, females can be determined only through the males collected in exactly the same locality. Therefore, in the present study, the key to species is mainly based on the characters of male genitalia, and this key does not help determine females. But under each Chinese species, we provide comparisons to similar species on external features as well.

Figures

Figures 28 - 35. Female genitalia of Pterostichus (Koreonialoe) spp. from China, Figs 28 - 31 ventral view and inner lateral view of ovipositor. Figs 32 - 35 female reproductive system. 28, 32 P. tetralobatus, Paratype from Laopingding, Liaoning 29, 33 P. syleus, a female from Baishilazi, Liaoning 30, 34 P. micropoides, female, Paratype from Antu county, Jilin 31, 35 P. bellatrix, a female from Fusong county, Jilin. Scale bar: 0.5 mm. Abbreviations: g 1: gonocoxite I; g 2: gonocoxite II; es: ensiform setae; ns, nematiform setae; bc: bursa copulatrix; co: common oviduct; sc: seminal canal; rc: receptaculum; spc: spermathecal canal.