Lesticus Dejean, 1828

Fedorenko, D. N., 2022, New or little-known Lesticus Dejean, 1828 (Coleoptera: Carabidae: Pterostichini) from Vietnam, Russian Entomological Journal 31 (3), pp. 260-275 : 261-264

Lesticus Dejean, 1828

Dejean, 1828: 189; Lacordier, 1854: 312; Chaudoir, 1868: 155; Tschitschérine, 1900: 186; Kuntzen, 1914: 43; Andrewes, 1930: 194; Dubault et al., 2008: 239; Roux et al., 2016: 22–25, 229; Zhu et al., 2018: 156. — Triplogenius Chaudoir, 1852: 71 (type species: Trigonotoma bicolor Laporte de Castelnau, 1834 = Lesticus viridicollis ( Macleay, 1825) , designated by Moore [1987]). — Trigonomina Motschulsky, 1865: 349 (type species: T. politocollis Motschulsky, 1865 , by monotypy). — Trigonomima Csiki, 1929 et auct. [nom. nud., incorrect spelling]. — Celistus Tschitschérine, 1900: 186 (type species: L. andamanensis Chaudoir, 1878 , by original designation).

Type species: Lesticus janthinus Dejean, 1828 (by monotypy).

DIAGNOSIS. A member of the ‘Trigonotomi’ group distinctive in having the combination of antennal scape short, pedicel with seta; labral setae evenly spaced; clypeus anteriorly truncate; gula moderately wide; mentum tooth transverse and slightly bifid (vs. subtruncate and slightly rounded); elytral stria 7 with 3 preapical setae.

Other characters as for the group: abdominal sternites transversely sulcate; mentum with deep labial pits; elytral umbilical seta series (USS) continuous. Aedeagus with medi- an lobe more or less symmetrical, slightly flattened dorsoventrally and slightly curved in lateral view; right paramere short; internal sac dorsal or almost so; right paramere short.

REDESCRIPTION. Body macropterous to apterous, mostly large, BL 11–35 (mostly 16–30) mm, shiny, uniform black to bright metallic. Eyes ( Figs 1–12 ) moderately convex, gena distinct, neck constriction mostly shallow yet distinct. Mandibles moderate in length, with apex very pointed and strongly incurved. Labrum slightly sinuate at middle of apical margin. Frontal sulci mostly long, reaching the level of posterior supra-ocular seta, deep and sinuous.

Pronotum ( Figs 13–24 ) cordiform to quadrate or round- ed, with basal angles acute to completely rounded, respectively. Lateral bead from narrow all along to distinctly broadened and flattened toward base, more so in basal fourth. Basal foveae moderately deep and rather flat at bottom, smooth to densely punctate or rugose, inwardly limited by a distinct, mostly deep, inner basal sulcus; outer basal sulcus running close to lateral margin and merged, i.e., directly extended, into lateral groove inside lateral bead. Base without bead.

Elytra mostly parallel-sided or almost so. Basal ridge entire to missing. Striae mostly deep and distinctly punctate or crenulate; parascutellar striole separate and long; stria 1 adjoining parascutellar seta. Interval 3 with three discal setae, d1 adjoining stria3, d2 and d3 adjoining stria 2; these setae varying between species in position, as well as in number, from 4–5 to missing. Intervals mostly becoming more convex toward apex and often toward lateral margin.

Leg setation: profemur with posterior face trisetose, metacoxa bisetose (inner seta missing), metafemur with one seta (basal), metatibia externally setose, Tarsi without lateral setae; ventral setae strong, spiniform, arranged in two rows, tarsomere 5 ventrally setose; tarsomeres 2 and 3 with dorsoapical setae. Meso- and metatarsomeres 1–4 with anterolateral (outer) carina varying between species from long and sharp through blunt and apically shortened to missing, with only ventrolateral sulcus (that beneath the carina) only traceable.

Ventral side smooth, propleura, sides of meso- and metathorax more or less punctate, abdominal sternites II (along base) and III (at middle) less so. Prosternal process not beaded, with posterior inclination rather wide and flat. Metepisternum long to short.

Secondary sexual characters. Protarsomeres 1–3 dilated and biserially squamose on ventral side in male (vs. not dilated, without ventral pad, in female — for details see also ‘Comments’ below). Labial palpomere 3 more dilated toward apex in male than in female, while varying from species to species considerably in shape, from very slightly dilated, subtriangular, to broadly triangular. Elytra often slightly shorter in female than in male, with apices truncate combined (vs. somewhat pointed but blunt tips); intervals flattened, more so behind middle (vs. more convex before apex than on disc). This is especially true of interval 2 which is equally wide throughout its length or slightly broadened toward apex and almost flat in apical third, often with a few punctures just before apex (vs. distinctly narrowed and increasingly convex toward apex, and impunctate).

Aedeagus ( Figs 25–39 , 40–45 ): everted and inflated internal sac with more or less homologous bulbs, a–f. Two sclerotized strips, or lateral ligules, left and right, are traceable on each side of apical orifice. Left ligule much reduced, short and vague, right one (= basal band sensu Zhu et al. [2018]) mostly very distinct, long or very long.

Female pregenital segment, genitalia and reproductive tract (Figs 46–53): Tergite VIII with latero-apical membranous parts sclerotized, extended, and curved ventrad. Sternite VIII moderately densely setose along apical margin. Urite IX: laterotergite densely setulose at apical margin; gonocoxite falcate, long and smooth. Spermatheca moderately long, somewhat helminthoid, and forked, one branch being much shorter than the other. Common oviduct and spermatheca each with a well-developed rounded bulb, probably sphincter, at base, these being large or small, respectively.

COMMENTS. Triplogenius having been described, Lacordier [1854] soon after recognized this genus as synonymous with Lesticus , and Tschitschérine [1900] considered the two taxa as subgenera defined chiefly by long or short metepisternum, respectively. The recent authors [ Roux et al., 2016; Zhu et al., 2018] avoid this division or subdivision and I incline to their opinion, too. Zhu et al. [2018] also briefly discussed evolution of some characters, including the length of metepisternum. This varies much between species of the genus, ranging from much longer than wide in some species to slightly wider than long in the others. The two character states are known to depend on a particular wing condition, macropterous or apterous, respectively. This latter condition has been observed in species from different and not closely related species groups, which satisfies doubts about parallel development of characters resulted from the aptery. As a general rule, apterous species live in mountains at higher altitudes, whereas their macropterous allies prefer to inhabit lowland places.

Zhu et al. [2018] also described four types, I to IV, of the internal sac of aedeagus, with type I subdivided into ‘the auricollis -form’ and ‘the chalcothorax -form’. All these types covered more than one species while type III was found in L. magnus only. These names, including L. insignis as illustrative of the aedeagus type IV, are here used for species groups chiefly defined by endophallic characters, i.e., the auricollis - group, the chalcothorax -group, and the insignis -group. My understanding of endophallic types observed within Lesticus , as well as species groups based on these types, is similar but three minute exceptions: (1) ‘the auricollis -form’ and ‘the chalcothorax -form’ are considered as separate and very different types; (2) L. andamanensis seems to be different enough from L. praestans and L. nubilus to recognize the former and the latter two as distantly related and thence belonging to different species groups; (3) endophallus type III is supposed to be a far advanced variant of the chalcothorax - type, which invites L. magnus to be placed within the chalcothorax -group.

Very few morphological characters other than endophallic ones are useful to discriminate between species groups. Among them, lateral (precoxal) longitudinal ridges of the mesoventrite are either entire (the insignis -, the chalcothorax - and the putzeysi -group) or interrupted just in front of mesocoxa to form a small tooth visible in posterolateral or anterolateral and diagonal view (the auricollis -, the janthinus -group, etc.). Another significant character is the labial palpomere 3. It is of particular shape in at least male, either broadly triangular, slightly shorter at apex than long at inner margin (many species, including those of the auricollis -, the chalcothorax -, the putzeysi -group, etc.), or slender and slightly triangular, much longer than wide at apex (for instance, the janthinus -group and the insignis -group).

Some characters are interesting in terms of character and/ or phyletic evolution.

(1) Right paramere is short, with apex narrowly rounded to truncate, and similar in shape in many species, while varying considerably within a species, which results in very slight interspecific differences if at all. Some species ( Figs 35–39 ) exhibit a small, membranous, preapical region. It is observed in all specimens examined ( L. auricollis , L. bellus sp.n., L. verticillatus sp.n.) or only in some of them ( L. attenuatus sp.n.).

(2) Pronotal anterolateral seta is doubled on one or both sides in some specimens of L. janthinus while single anterolateral seta is characteristic of most congeners.

(3) Some closely and distantly related species of the genus have evolved protarsomere 1 with a rudimentary ventral pad in female (Fig. 54). This, very special, character is peculiar to L. nubilus and L. laevis sp.n., while being observed in some specimens/populations of L. praestans , L. bellus sp.n. and L. lakhonus . This may suggest that the missing ventral pad is plesiomorphic state in the genus or at least in its some species groups.

Altogether ten species have been recorded in Vietnam, all similar in body shape due to the elytra more or less parallel-sided and pronotal sides not or vaguely sinuate in front of basal angles; these being obtuse and blunt or narrowly rounded. Of these species, two belong to the insignis -group, 1–2 to the chalcothorax -group, and six to the auricollis -group.

The species of the latter group are large-sized, with dorsum mostly metallic, often bright metallic, and the pronotum subquadrate; no appreciable sexual differences in body ratios, notably EL/EW, has been found in them. Three of six species reviewed, L. auricollis , L. praestans , and L. nubilus , are well-known and widespread, all being macropterous and dwelling in lowlands or at lower altitudes in mountains. The remaining three species have species ranges restricted following apterous condition of their adults.

Lesticus auricollis , L. bellus sp.n. and L. verticillatus sp.n. have similar facies, resulting from similar body colour, proportions, elytral and, especially, pronotal sculpture. Their aedeagi ( Figs 25–45 ) also are similar, which is due chiefly to the bulb c divided into two because of its dorsal process cd well separated, rather short and straight, while ranging from large to indistinct (vs. cd long, apically curved and not separated from bulb c in the remaining three species of this group). Lesticus bellus sp.n. and L. verticillatus sp.n. seem to be closer to each other than to L. auricollis , as they share bulb a missing, whereas it is well-developed in the other four species. This suggests the interrelationships: ( L. praestans + ( L. nubilus + L. attenuatus sp.n.)) + ( L. auricollis + ( L. bellus sp.n. + L. verticillatus sp.n.)) or ( L. praestans + ( L. nubilus + L. attenuatus sp.n.)) + L. auricollis ) + ( L. bellus sp.n. + L. verticillatus sp.n.)).

Among the species recorded in Vietnam, I have not seen L. latissimus only, which thus is not included in the key below. This species was described from Kep (‘Kep, Tonkin’), Bac Giang Province, northern Vietnam, and said in the description [ Dubault et al., 2012] to be different from similar congeners from the region they populated in having the elytra long, with apices rounded separately each. Aedeagus [ Roux et al., 2016: 341] is peculiar due only to its apex being triangular in dorsal view (vs. rounded in L. buqueti as the most similar species from there). The two species otherwise are very similar in virtually all characters, including body appearance, and all body ratios are within variation ranges of L. buqueti .

GEOGRAPHIC DISTRIBUTION. Throughout the Oriental region and the adjacent parts of southernmost Palearctic subregion within China to Japan.

Five specimens of L. janthinus , each with a handwritten label ‘ Сингапур. [ Singapore], V. 1902 г.’ or ‘МалайЯ, Джохор. [Malay Peninsula, Johore], 1902 г.’, have been found to be in no way different from a long series of specimens from Java (all kept in ZIN collection). Because this species and its close relatives are known to be confined to Java only, except for L. lautus Andrewes, 1930 from Sumatra, the labels cited are certain to be wrong.

HABITATS AND HABITS. The adults of many species are forest-dwellers of nocturnal activity; those of macropterous species flight to light at night. Many macropterous species prefer lowland habitats, mostly forests. Some of them, e.g., L. p. praestans , L. lakhonus , L. buqueti , were found to occur in numbers in a locality explored; among them, the former two and the latter being aboundant in a floodland forest or cornfields, respectively.

Figures

Figs 1–12. Head: 1–2 — Lesticus nubilus, 2♂♂; 3 — L. attenuatus sp.n., ♂ paratype; 4 — L. p. praestans, ♂ from Cuc Phuong NP, Vietnam; 5 — L. p. mouhotii, ♀ from Mondulkiri Prov., Cambodia; 6 — L. auricollis, ♂ from Bac Giang Prov., Vietnam; 7–8 — L. verticillatus sp.n., ♂ paratype from Song Thanh NP and ♂ holotype; 9 — L. bellus sp.n., ♀ holotype; 10 — L. buqueti, ♀; 11 — L. lakhonus, ♀; 12 — L. laevis sp.n., ♂ holotype; 1, 10–11 — Cat Tien NP, Vietnam; 2 — Mae Vong env., Thailand. Рис. 1–12. Голова: 1–2 — Lesticus nubilus, 2♂♂; 3 — L. attenuatus sp.n., паратип ♂; 4 — L. p. praestans, ♂ иЗ Нац. парка Кыкфыонг, Вьетнам; 5 — L. p. mouhotii, ♀ иЗ пров. Мондулкири, Камбоджа; 6 — L. auricollis, ♂ иЗ пров. БакЗЯн, Вьетнам; 7–8 — L. verticillatus sp.n., паратип ♂ иЗ нац. парка Сонгтхань и голотип ♂; 9 — L. bellus sp.n., голотип ♀; 10 — L. buqueti, ♀; 11 — L. lakhonus, ♀; 12 — L. laevis sp.n., ♂ голотип; 1, 10–11 — Нац. парк Катьен, Вьетнам; 2 — окр. Мае Вонг, Таиланд.

Figs 13–24. Pronotum: 13–14 — Lesticus nubilus, 2♂♂; 15 — L. attenuatus sp.n., ♂ paratype; 16 — L. p. praestans, ♂ from Cuc Phuong NP, Vietnam; 17 — L. p. mouhotii, ♀ from Mondulkiri Prov., Cambodia; 18 — L. auricollis, ♂ from Bac Giang Prov., Vietnam; 19– 20 — L. verticillatus sp.n., ♂ paratype from Song Thanh NP and ♂ holotype; 21 — L. bellus sp.n., ♀ holotype; 22 — L. buqueti, ♀; 23 — L. lakhonus, ♀; 24 — L. laevis sp.n., ♂ holotype; 13, 22–23 — Cat Tien NP, Vietnam; 14 — Mae Vong env., Thailand. Рис. 13–24. Переднеспинка: 13–14 — Lesticus nubilus, 2♂♂; 15 — L. attenuatus sp.n., паратип ♂; 16 — L. p. praestans, ♂ иЗ Нац. парка Кыкфыонг, Вьетнам; 17 — L. p. mouhotii, ♀ иЗ пров. Мондулкири, Камбоджа; 18 — L. auricollis, ♂ иЗ пров. БакЗЯн, Вьетнам; 19–20 — L. verticillatus sp.n., паратип ♂ иЗ нац. парка Сонгтхань и голотип ♂; 21 — L. bellus sp.n., голотип ♀; 22 — L. buqueti, ♀; 23 — L. lakhonus, ♀; 24 — L. laevis sp.n., ♂ голотип; 13, 22–23 — Нац. парк Катьен, Вьетнам; 14 — окр. Мае Вонг, Таиланд.

Figs 25–39. Aedeagus: 25–26 — Lesticus praestans mouhotii; 27–28– L. nubilus; 29–30, 38–39 — L. attenuatus sp.n., paratypes; 31– 32, 35 — L. auricollis; 33–34, 36 — L. bellus sp.n., paratype; 37 — L. verticillatus sp.n., paratype; 25–34 — median lobe with everted and inflated internal sac; 25, 27, 29, 31, 33 — caudal aspect; 26, 28, 30, 32, 34 — anterodorsal aspect; 35–39 — right paramere, left aspect; a, b, bb, c, cd, d, e, ed, ev, f — bulbs of internal sac. Scale bars 2 mm (25–34) or 1 mm (35–39). Рис. 25–39. Эдеагус: 25–26 — Lesticus praestans mouhotii; 27–28– L. nubilus; 29–30, 38–39 — L. attenuatus sp.n., паратипы; 31– 32, 35 — L. auricollis; 33–34, 36 — L. bellus sp.n., паратип; 37 — L. verticillatus sp.n., паратип; 25–34 — среднЯЯ долЯ с вывернутым и надутым внутренним меШком; 25, 27, 29, 31, 33 — каудально; 26, 28, 30, 32, 34 — антеродорЗально; 35–39 — праваЯ парамера, слева; a, b, bb, c, cd, d, e, ed, ev, f — пуЗыри внутреннего меШка. МасШтаб: 2 мм (25–34) или 1 мм (35–39).

Figs 40–45. Aedeagus, median lobe with everted and inflated internal sac: 40–41 — Lesticus buqueti, ♂♂ from Java (40) or Vietnam (41); 42–43 — L. lakhonus; 44–45 — L. laevis sp.n., holotype; 40–41, 43, 45 — right dorsolateral aspect; 42, 44 — left ventrolateral aspect; b, c, d, e — bulbs of internal sac. Scale bars 1 mm. Рис. 40–45. Эдеагус, среднЯЯ долЯ с вывернутым и надутым внутренним меШком: 40–41 — Lesticus buqueti, ♂♂ с Явы (40) и иЗ Вьетнама (41); 42–43 — L. lakhonus; 44–45 — L. laevis sp.n., голотип; 40–41, 43, 45 — справа и сверху; 42, 44 — слева и сниЗу; b, c, d, e — пуЗыри внутреннего меШка. МасШтаб: 1 мм.