Platymetopus flavilabris ( Fabricius, 1798 )

Kataev, Boris M., 2023, A review of Asian species of the genus Platymetopus (Coleoptera: Carabidae: Harpalini), Zootaxa 5306 (5), pp. 501-536 : 504-508

Platymetopus flavilabris ( Fabricius, 1798)

( Figs. 1–41 )

Carabus flavilabris Fabricius, 1798: 59 . Type locality: “ India orientalis”.

Description. Body length 6.6–9.4 mm. Body proportions in Table 1 . Habitus as in Figs. 1, 2 , 13, 14 , 21–26 , 32, 33 ).

Body blackish brown to black, with unicolorous elytra; dorsum mat or shiny, with or without metallic green or bronze tinge. Palpi, antennae from antennomere 2 to 4 and tarsi more or less infuscate to black, basal palpomeres and antennomeres yellow or brownish yellow; femora and tibiae brownish yellow to black.

Head with large convex eyes; tempora flat, oblique; genae slightly wider than antennomere 1. Labral apex almost straight or very shallowly concave at middle. Supraorbital pore small, located close to supraorbital suture at or slightly before of level of posterior margin of eye. Frons and vertex densely punctate or rugose-punctate, with or without microsculpture between punctures. Labium as in Fig. 3 . Mandibles short, with almost straight mesal margin apically. Antennae either surpassing pronotal basal margin or not reaching it.

Pronotum comparatively wide, widest before middle. Sides rounded along entirely length or almost rectilinearly converging in basal third; lateral bead complete, very narrow throughout; lateral furrow very narrow, shallow; medial lateral seta inserted slightly before widest point. Apical margin deeply emarginate, bordered along entire length. Apical angles markedly prominent anteriorly, very narrowly rounded at apex. Basal margin almost equal to or slightly longer than apical margin, markedly shorter than elytral base, distinctly bordered along entire length, ciliate. Basal angles very obtuse, generally with a tiny obtuse denticle at apex. Disc moderately convex, more or less depressed laterobasally. Basal foveae wide and shallow, indistinct outlines, fused with laterobasal depressions. Median line superficial, short, markedly not reaching anterior and basal margins. Anterior and posterior transverse depressions absent or very wide and indistinct. Surface densely punctate or rugose-punctate, with or without microsculpture between punctures.

Elytra elongate oval, widest behind middle, convex on disc and somewhat gently sloping to apex. Humeri slightly prominent, rounded, generally without denticle, occasionally with a tiny obtuse denticle recognizable behind. Lateral margins smooth along entire length. Preapical sinuation deep and long; sutural angle acutangular, narrowly rounded at tip. Basal border slightly sinuate, forming a very obtuse, indistinct angle with lateral margin. Striae slightly impressed along entire length, coarsely punctate anteriorly, gradually becoming smooth behind middle. Intervals either equally wide or intervals 3, 5 and 7 slightly wider than neighboring. Discal setigerous pores absent. Marginal umbilicate series divided in basal and apical groups, each consisting of 6–8 setigerous pores. Punctation fine and dense, with five to seven punctures across each interval in its middle portion. Microsculpture between punctures present throughout, consisting of slightly transverse meshes.

Prosternal process with border. Proepisternum indistinctly or coarsely punctate. Metepisternum narrow, much longer than wide, strongly narrowed posteriorly. Wings fully developed.

Metatarsus slender, in male slightly longer than HWmin, in female about as long as HWmin, in both sexes densely setose ventrally. Male pro- and mesotarsomeres 1–4 only slightly dilated, each with adhesive vestiture.

Apex of abdominal sternite subtruncate in male and rounded in female, in both sexes with two pairs of marginal setigerous pores.

Female genitalia ( Figs. 4–6 ): laterotergite with well sclerotized rounded apex and bearing one apical seta; distal mesal angle of gonosubcoxite prominent posteriorly forming a shot narrow spur with a long seta at apex; gonocoxite markedly shorter than gonosubcoxite, with one short thin seta on dorsal ridge of outer side.

Median lobe of aedeagus ( Figs. 7–12 , 15, 20 , 27–31 , 35–40 ) with large basal bulb; in lateral view bent before middle; its ventral margin almost straight or slightly convex medially; apex sharply bent ventrally, generally with a small ventroapical denticle; in dorsal view median lobe almost straight or scarcely curved, more or less evenly narrowed apically; terminal lamella slightly longer than wide, rounded apically; internal sac without spines and spiny patches.

Comparison. Platymetopus flavilabris can be recognized among other Asian congeners by the combination of the following distinctive characters: 1, comparatively large body size; 2, unicolorous dark elytra; 3, light, not infuscate basal antennomeres; 4, pronotum rather strongly narrowed basally; 5, median lobe of aedeagus with apex sharply bent ventrally and with a small ventroapical denticle. This species, especially the subspecies P. f. punctulatus , is very similar in its morphological characters to P. tritus , but the latter species is on average smaller, and it can be additionally distinguished by the characters listed in the key including the median lobe of the aedeagus more strongly bent ventrally in the apical third and with apex lacking a ventroapical tubercle. Interestingly, P. flavilabris , especially its nominotypical form, is similar in general habitus and morphological features, including male and female genitalia, to the Afrotropical P. vestitus Dejean, 1829 , which is widely distributed in tropical Africa and very common in the western part of the continent. The latter species differs from P. flavilabris mainly in having the preapical sinuation of the elytra deeper, and the median lobe of the aedeagus, as in T. tritus , more strongly bent ventrally in the apical third and with apex lacking a ventroapical tubercle. The great similarity of the two widely distributed allopatric species suggests that they are closely related.

Distribution ( Fig. 41 ). The species is very widespread from Pakistan, India and Sri Lanka in the west to Korea, Japan and the Philippines in the east and to the Malay Archipelago and Western New Guinea in the southeast.

Remarks. This species is highly variable in external morphological features, both geographically and within the same population, without noticeable differences in the structure of the male and female genitalia. The first researchers, working with very limited material, introduced numerous new names for its various forms, considering them mainly as separate species. Later, Andrewes (1921a, 1930), Csiki (1932) and Schauberger (1933) treated P. flavilabris in a broader sense as a widely distributed species, including several varieties, but their diagnostic characteristics and distribution were different for each author. More recently, Habu (1973) studied the variation of P. flavilabris throughout the whole geographical range and concluded that while some characters (mostly, color of legs, length of antennae, and punctation and microsculpture on head and pronotum) vary considerable, “it seems, however, difficult to draw lines as subspecies”. According to Habu (1973), the legs become darker from west to east, and from south to north; the antennae in the specimens from Japan are shorter than those from Southeast Asia; the head and pronotum are more coarsely punctate and lack microsculpture in the specimens from Japan, mainland China, Hong Kong, Taiwan, the Philippines, Java and in some from Vietnam; and the terminal lamella of the aedeagus is somewhat variable, however not geographically. As a result, he treated all the described forms as synonyms. Although Habu (1973) quite correctly described the general pattern of the geographical variability of this species, according to our data, it does not have a clinal character, since many of the distinctive features of the vicarious populations remain stable over large areas.

Based on the studied material and literature data, four subspecies with more or less wide zones of intergradation between them can be recognized within P. flavilabris : P. f. flavilabris , P. f. thunbergi , P. f. laticeps and P. f. punctulatus . Due to the very wide range of the species and the limited material from some regions, the boundaries between subspecies in places are largely arbitrary. Further study with the involvement of additional material from these regions will make it possible not only to clarify the boundaries, but also to better understand their nature.

Figures

FIGURE 41. Platymetopus flavilabris (Fabricius, 1798), distribution. Shaded area: populations with intermediate characteristics of P. f. thunbergi Quensel, 1806 and P. f. laticeps Dejean, 1829.

FIGURES 1–2. Platymetopus flavilabris flavilabris (Fabricius, 1798), habitus. 1, South India; 2, Nepal. Scale bar = 1.0 mm.

FIGURES 3–12. Platymetopus flavilabris (Fabricius, 1798): P. f. flavilabris (3, 5, 7–12), P. f. laticeps Dejean, 1829 (6). 3–5, 9, 10, Nepal; 6, China (Fujian); 7, 8, Sri Lanka; 11, 12, Myanmar (Yangon). 3, labium; 4, gonocoxite; 5, 6, laterotergite, gonosubcoxite, and gonocoxite; 7–12, median lobe of aedeagus. Lateral (4, 8, 10, 12), ventral (3, 5, 6) and dorsal (7, 9, 11) views. Scale bar = 1.0 mm.

FIGURES 13–14. Platymetopus flavilabris thunbergi Quensel, 1806, habitus. 13, Laos; 14, Southern Vietnam. Scale bar = 1.0 mm.

FIGURES 15–20. Platymetopus flavilabris thunbergi Quensel, 1806, median lobe of aedeagus. 15, 16, Southern Vietnam; 17, 18, Laos; 19, 20, Thailand. Dorsal (15, 17, 19) and lateral (16, 18, 20) views. Scale bar = 1.0 mm.

FIGURES 21–22. Platymetopus flavilabris laticeps Dejean, 1829 (transition to P. f. thunbergi Quensel, 1806). 21, Northern Vietnam; 14, Hainan). Scale bar = 1.0 mm.

FIGURES 23–24. Platymetopus flavilabris laticeps Dejean, 1829, habitus (Japan). Scale bar = 1.0 mm.

FIGURES 25–26. Platymetopus flavilabris laticeps Dejean, 1829, habitus (Philippines). Scale bar = 1.0 mm.

FIGURES 27–31. Platymetopus flavilabris laticeps Dejean, 1829, median lobe of aedeagus. 27, 28, Japan; 29, 39, China (Yunnan); 31, China (Fujian). Dorsal (27, 29) and lateral (28, 30, 31) views. Scale bar = 1.0 mm.

FIGURES 32–34. Platymetopus flavilabris punctulatus (MacLeay, 1825) (32, 33, habitus; 34, labels). 32, Sumbawa; 33, Sulawesi, holotype of P. subrugosus Schauberger, 1938. Scale bar = 1.0 mm.

FIGURES 35–40. Platymetopus flavilabris (Fabricius, 1798):P.f.laticeps Dejean, 1829 (35–38) and P. f.punctulatus (MacLeay, 1825) (39, 40), median lobe of aedeagus. 35, 36, Philippines; 37, 38, Moluccas (Ternate); 39, 40, Sumbawa. Dorsal (35, 37, 39) and lateral (36, 38, 40). Scale bar = 1.0 mm.