Taridius Chaudoir, 1875

Fedorenko, Dmitri N., 2012, Notes on the genus Taridius Chaudoir, 1875 (Coleoptera, Carabidae, Lebiini), with descriptions of six new species from Vietnam, ZooKeys 244, pp. 67-89 : 68-72

Genus Taridius Chaudoir, 1875

Type species:

Taridius opaculus Chaudoir, 1875, by monotypy.

Redescription.

Body medium-sized, subconvex to flattened. Dorsum glabrous, ventral surface glabrous or sparsely ciliate. Body dark brown to black, mouthparts, clypeus anteriorly, antennae, legs, propleura, reflexed side margin of pronotum, pronotal apex before site of front transverse impression, as well as base behind basal transverse impression mostly pale, yellow. Elytra black or dark brown, usually with a pale, yellow to pale brown, side border, epipleura and an ornate pattern which sometimes bears very slight bronzed reflexions over dark color. This pale pattern (Fig. 1) is generally composed of a large apical spot (PAS) and a humeral vitta (PHS) subdivided into two. Its external part, PHSe, long, running on intervals 6 and 7 and expanded onto 5th behind, while a shorter and smaller internal part, PHSi, occupying intervals 2 to 4 or 3 and 4 before middle. When increasingly extended backwards, PHSe makes a subequally wide, dark, subtransverse, medial fascia (DMF) constricted in interval 6 first (Figs 3-5) and divided into a common (post)median spot (DMS) and a submarginal strip (DLS) after (Figs 8-10). DLS runs on intervals 7 and 8, while tending to be reduced to a small patch at the middle and another one, vague to missing, behind shoulder. The remaining part of the dark pattern, a rounded to quadrate dark spot around scutellum on intervals 1 to 4-5 (DSS) is extended into a sutural strip (DSF) running on intervals 1-2 and tapering behind DMF or DMS. When entire, the dark pattern resembles a flying bird with open wings. Middle of prosternum, meso- and metaventrite mostly pale, reddish or reddish-yellow.

Microsculpture isodiametric on head and elytra, before anterior transverse impression and behind basal transverse impression of pronotum, as well as along its side margin and often also over its more or less wide, posterolateral area. Microsculpture on pronotal disc grated, composed of transverse, very wide and evenly rectangular meshes, rarely these being isodiametric ( Taridius coriaceus sp. n.). Sometimes longitudinal meshes traceable along side margin between antero- and posterolateral setigerous pores ( Taridius piceus sp. n.). Elytral microsculpture conspicuous, that on head and pronotal disc often obsolete. Head and pronotum minutely and sparsely punctate.

Eyes convex, genae short to rather long but not or barely projecting, head mostly broadest level to a little before 1/2 length of eye tubercle (eye and gena combined); frontal longitudinal carinae 2-5, rarely seven, on each side. Labrum rectangular, wider than long, very slightly emarginate at and sexsetose along front margin. Submentum bisetose, tooth of mentum stout, rather widely rounded apically, with two setae at middle. Ligula rather wide, truncate, bisetose, paraglossae adnate, slightly surpassing ligula, widely rounded apically. Penultimate labial palpomere plurisetose internally, apical joint fusiform to subtriangular. Antennae filiform, pubescent from antennomere 4 onwards, about last three joints surpassing elytral base, antennomeres 1, 3 and 4 subequally long, 3rd two thirds to nine tenths longer than 2nd; basal three joints with several cilia or very short hairs in addition to standard setae, 2nd mostly with three, preapical, lateral setae anteriorly.

Pronotum bisetose on each side, exceptionally trisetose anteriorly ( Taridius opaculus ), subcordate, broadest far before middle, with front margin slightly sinuate, front angles angles which barely projecting in the latter case. Anterior border interrupted medially, straight or barely sinuate before base; hind angles subrectangular to predominantly obtuse or highly so and rounded. Base oblique towards and often rounded at hind angles which hardly projecting in the latter case. Anterior border interrupted medially, basal border entire, sometimes weaker or interrupted in the middle. Side margin rather widely explanate and strongly reflexed, more so basad, often with more or less dense and large but shallow punctures throughout or only basally. Mid-line fine but moderately deep, extremities excluded, both front and basal transverse impressions weak to indistinct, basal foveae wide, shallow, mostly reduced to a small but rather deep pit just before basal border, giving rise to side gutter, basal transverse impression and a fine to indistinct paralateral line as internal border of basal fovea. A flattened area between this line (or its virtual forward extension) and side border rather densely transversely rugulose, sometimes coriaceous, a sparser and shallower rugosities over disc.

Elytra oblong-oval, humeri rounded, apical truncature slightly oblique, a little sinuate, with outer angle widely or obtusely rounded, apices truncate and mostly sharp, rectangular to slightly obtuse, with an almost indistinct re-entrant angle in the latter case. Angle between side and basal borders (humeral angle) absent or, exceptionally, highly obtuse opposite stria 7, basal border entire and slightly sinuate. Elytral striae moderately deep all along, impunctate or crenulate at base, intervals flat, sometimes (individual variability) odd narrower and a little more convex than even ones. Interval 8 sharply carinate internally in anterior three fourths. Dorsal setigerous pores two, evenly spaced along stria 3, exceptionally ( Taridius nilgiricus Andrewes, 1935) serial on intervals 3 and 5. Umbilicate series uninterrupted and composed of ca 16 setigerous pores. Wings well-developed in all congeners examined but Taridius piceus sp. n. Metepisterna long.

Apical margin of last abdominal sternite (VII) bisetose in both sexes but quadrisetose in females of Taridius disjunctus sp. n., Taridius wrasei Kirschenhofer, 2010 and Taridius andrewesi Emden, 1937.

Profemur unisetose in the middle of postero-ventral edge, metacoxa bisetose along outer margin of its posterior part, metatrochanter unisetose, metafemur bisetose; meso- and metatibia dorsally with a more or less distinct, longitudinal sulcus, its edges carinate or at least sharp. Tarsi glabrous dorsally, claw joint setose beneath, claws pectinate. Meso- and metatarsomere 1 as long as the following two combined. Basal three protarsomeres of male dilated and furnished with adhesive vestiture.

Penis (Figs 17-28) in dorsal view mostly with a wide, premedian, swell on right side, apical lamella subtriangular to parallel-sided, widely rounded at tip. Parameres of similar shape in different species (Figs 29-32).

Female gonocoxite IX with two, inner (dorsal) and outer (ventral), ensiform setae varying in size between species. The best developed gonocoxite and setae, especially inner ones, tend to be reduced from Taridius disjunctus sp. n. to Taridius coriaceus sp. n. (Figs 39-46), inner seta becoming very small and invisible in some species (Figs 43-46).

Geographic distribution.

Widespread in South and South-East Asia, from North India and Indochina in the north to Borneo and Java in the south.

Habits and habitats.

The beetles occur at the altitudes of 150-1800 m asl where they dwell in leaf-litter of monsoon, broad-leaved, tropical or subtropical forests. Only two specimens of Taridius ornatus were taken in coniferous forests, among them a paratype collected in a Pinus dalatensis forest using pitfall traps and a female from Chu Yang Sin caught by hands in leaf-litter of an elfin wood under trees of Chamaecyparis hodginsii (Dunn, 1908). At higher altitudes, the adults were predominantly taken by pitfall trapping. This is true of Taridius ornatus and Taridius piceus found to occur syntopically. At low altitudes, beetles mostly flew to lights at night. These were Taridius fasciatus and Taridius abdominalis taken together, as well as a paratype of Taridius disjunctus . A specimen of Taridius abdominalis sp. n. was sifted from bamboo leaf litter and individual specimens of the other species ( Taridius coriaceus , Taridius disjunctus , Taridius wrasei ) were only occasionally collected by hand on the soil surface.

It follows also that up to five species can live sympatrically and at least two syntopically as well. The sympatric species were found to be as follows: (1) Taridius ornatus , Taridius piceus , Taridius disjunctus , Taridius coriaceus and Taridius fasciatus in the Bi Doup - Nui Ba Nature Reserve, (2) (1) Taridius ornatus and Taridius disjunctus in the Chu Yang Sin National Park, (3) Taridius fasciatus and Taridius abdominalis in the Bu Gia Map National Park.

In addition, the fact that different species or their groups show female styli of strongly different structure implies differences in the substrates, soil or leaf-litter of different kind, the larval stages inhabit.

Comments.

(1) The congeners are all alike because of a great similarity in body shape. Yet, when combined, the color patterns of both the elytra and the ventral sur face of the hindbody are features sufficiently distinctive to discriminate most of the species with certainty.

(2) According to Kirschenhofer (2010), two structural characters, the shape of the last labial palpomere and the number of pronotal anterolateral setae, separate the subgenus Perseus from the nominate one which comprises Taridius opaculus only. In particular, a spindle-shaped palpomere and a single, standard, seta on the pronotum are peculiar to the former subgenus, whereas a subcylindric palpomere, combined with three anterolateral setae, to the latter. However, the palpomere has been found to be somewhat variable in shape. Firstly, it is subcylindric in males but fusiform in females. Secondly, the apically broadest palpomere is that of Taridius piceus sp. n., the species showing only one anterolateral seta on the pronotum. This leaves the polymerous anterolateral setae on the pronotum as the only support to an isolated position of Taridius opaculus . Yet, the support is weak because some other characters taken separate, eg, the serial dorsal setae on the elytra in the case of Taridius nilgiricus , could also provoke the erection of a monobasic subgenus if necessary, polymerous pronotal and elytral setae are deemed hardly different for that purpose. Based on the above evidence, I refrain here from subdividing the genus into the subgenera pending a comparative analysis of male and female genitalia, as well as the number of setae on abdominal sternite VII of the female.

At least two lineages have been traced within the genus. The members of the first lineage share the last abdominal sternite bisetose in both sexes, as well as rather weak female styli supplied with strongly reduced ensiform setae. In addition, the dark elytral pattern is mostly entire, the facial carinae are more numerous, and often also the dorsal microsculpture is superficial on the head and pronotum. In the second lineage which includes Taridius wrasei , Taridius disjunctus sp. n., Taridius andrewesi and probably also Taridius pahangensis (Kirschenhofer, 2003), females are distinctive in showing four setae on the last abdominal sternite. A rather pale elytral pattern, conspicuous dorsal microsculpture, less numerous frontal carinae and strongly armed female styli, albeit this feature has been examined in but two species, are among additional characters of the lineage.

Key to species of Taridius