Trechus bohemorum Pawlowski, 1973

Kostova, Rumyana & Bekchiev, Rostislav, 2025, New insights into the taxonomy of Trechus Clairville, 1806 (Coleoptera: Carabidae) in the Balkans, with the first description of the male of Trechus bohemorum Pawlowski, 1973, Zootaxa 5661 (4), pp. 538-552 : 540-544

Description of male Trechus bohemorum Pawlowski, 1973 .

Type material: BULGARIA: Holotype: 1 ♀ ‘Šarlir, Pirin, Mac.VII.32, Mař & Táb.’ ( NMPC) ; Paratype: 1 ♀ ‘Samokov, M. Hilf 1911, coll. O. Leonhard’ ( NMPC) .

Additional material examined: T. bohemorum BULGARIA: 1 ♀ ‘ Šarlir, Pirin, Mac. VII.32, Mař & Táb’ (NMPC); 1 ♂ ‘ BG Zemen Gorge, N42.450278 E22.708611, 23.X. 2000, 583 m a.s.l., leg. D. Gradinarov’ (BFUS-CAR000001); T. kobingeri Apfelbeck, 1902 ALBANIA: 1 ♂ ‘ Shkoder, m. e. Cukalit m-t, 1300 m, 27.VI.2001, P. Moravec lgt.’ (PMLC); T. kobingeri pawlowskianus BULGARIA: 2 ♂♂ ‘Rilo Dagh., Collectio de Obenberger, Mus. Pragense’ (NMPC); T. pirinicus Pawlowski, 1972 1 ♂ ‘ BULGARIA mer., Pirin b., 3.VI. 1998, Kalugera Cerna gora, 1600–1800 m n.m., L. Mencl lgt.’ (PMLC); T. merkli Pawlowski, 1973 BULGARIA: 1 ♂ ‘ Stara planina, Berkovska pl.: Kom hut, 1650 m 23.VII.2000, P. Moravec lgt.’ (PMLC); 1 ♂ same as previous but 24.VII.2000 (PMLC) BULGARIA: 1 ♂ ‘bor, Stara planina, Kom : 1700–2000, 17.VI.1996, Libor Klima lgt.’ (PMLC); T. obtusiusculus Ganglbauer, 1889 MONTENEGRO: 1 ♂ ‘ Durmitor Mont , Savin Kuk , 2000 m, 30.VI.1958, Mař. Hoberl. lgt.’ (NMPC); T. zarandicus Moravec, 1986 ROMANIA: holotype: 1 ♂ ‘ Mt. Zarand : vf. Drocea-Madrigesti , 17.VII.1984, 400–600m, P. Moravec lgt.’; paratypes: 2 ♀♀ same as previous (PMLC).

Despite being described from female specimens, T. bohemorum has quite distinct diagnostic characters—its elytra shape (elongated with slightly arcuated sides) and the presence of wings ( Pawlowski 1973). In the zoological collection of Sofia University BFUS, a male specimen of the “ obtusiusculus ” group was deposited that has characters matching the description of T. bohemorum . The material was compared with female type specimens of T. bohemorum of deposited at the NMPC. In addition to the two specimens described by Pawlowski (1973), a third female specimen of the species bearing the same label as the holotype was found and identified by Pavel Moravec in 1997 in the NMP collection. We found that the male specimen from the BFUS collection matches morphologically both the type series and the description with illustrations of the habitus by Pawlowski (1973). Thus, this specimen represents the first documented male of T. bohemorum .

Diagnosis

T. bohemorum differs from the other representatives of the T. “ obtusiusculus ” group in less elongated median lobe of male genitalia without clear constriction near basal bulb, straight and rather wide distal portion in dorsal view, and small button-like apex in lateral view. Additionally, it differs from most representatives of the group in elongate habitus with parallel-sided elytra widest in apical third (EL/EW = 1.4 ÷ 1.5; L/EL = 1.5 ÷ 1.7), a short and broad pronotum (PW/PL = 1.3 ÷ 1.6), and the presence of well-developed wings ( Fig. 1 ). The median lobe of the aedeagus in T. bohemorum , is similar to that of T. kobingeri pawlowskianus but differs in the basal bulb, with no narrowing at the place of junction with the main part in T. bohemorum . The bended upward tip of the apical part is also smaller in T. bohemorum in relation to T. kobingeri pawlowskianus , and the copulatory piece distally ends with a very small, thick spine in T. bohemorum ( Fig. 2 ). In addition, T. kobingeri pawlowskianus is wingless, the elytra are shorter, and the lateral margins of the elytra are more oval, while T. bohemorum has well-developed wings and more parallel elytra margins. In terms of elytral proportions, T. bohemorum resembles T. cephalonicus Winkler, 1914 but differs in the shape of the posterior angles of the pronotum, less pointed and projected in the former than in the latter. T. bohemorum also clearly differs from T. cephalonicus in the shape and internal structure of the aedeagus, which in the latter is clearly narrowed near the basal bulb, with much larger, strongly upward curved apical disc tip in lateral view and copulatory piece with long, protruding apical part. The variation in the metric characters and indices of the studied specimens are shown in Table 1 .

Description of the male

Body length 3.6 mm. Colour: dark brown; antennae, legs, and mouthparts paler, as in holotype. Microsculpture isodiametric, well visible at the head, pronotum and elytra base at magnitude 50×, disc shiny. Habitus as in Fig. 1 .

Head: Maximum head width (0.78 mm) at level of eyes, which are well-developed. Antennae reaching anterior third of elytra.

Pronotum: Transverse (PW/PL = 1.47), subcordate, with maximum width in first third; Lateral sides rounded anteriorly, slightly sinuate posteriorly, posterior angles obtuse with clearly visible protruding denticles (PW/PBW = 1.19). Basal margin protruding medially. Marginal setae: One in anterior third and one at posterior angle on each side.

Elytra: Elongate, almost parallel with maximum width in apical third, elytral apex with a prominent tooth near suture (EL/EW = 1.51). Striae 1–4 clearly visible, deeper in basal half and shallower towards apex. Only stria 1 deeply impressed along its entire length. Remaining striae obsolete, progressively fading laterally. Two discal setae on third interval close to third stria. Lateral marginal (umbilical) series consisting of four humeral setae, concentrated and narrowly spaced in basal third, and 2 + 2 setae widely spaced in posterior two-thirds. Reverse apical stria well-developed up to half of elytra apical third. Hind wings well-developed.

Male genitalia: Median lobe in lateral view, bent at nearly right (slightly obtuse) angle distal to basal bulb. The apical portion attenuate ventrally, ending in a distinct apical disc tip curved upward (see lateral and dorsolateral views in Fig. 2 ). The copulatory piece relatively long, triangular-shaped in lateral view, broad basally and pointed and slightly bent upward apically, distally ending with a miniature spine. Endophallus with hairy areas.

Habitat

Small riparian meadow along the Struma River surrounded by deciduous forest. Collected manually by soil sampling.

Geographical distribution

The known collecting localities are situated in southwestern Bulgaria, relatively distant from each other. There is also a big difference in their altitudes from 2172 m a.s.l. (‘Šarlir’, possibly a misspelling of the Sharaliya peak in the Pirin Mts.) to 583 m a.s.l. (Zemen Gorge) ( Fig. 3 ). However, the retention of functional wings is a prerequisite for a broader distribution.

Systematic position

The presence of functional wings in T. bohemorum — unique character among group members—led Pawlowski to consider it a basal species of the group ( Pawlowski 1973). The relatively simple archaic morphology of the median lobe—its medium size and small apical disc—is consistent with this interpretation.

Figures

FIGURE 1. Male habitus of Trechus bohemorum Pawl.

FIGURE 2. Median lobe of the male genitalia (A—lateral view, B—dorsal view, C—latero-dorsal view) of Trechus bohemorum Pawl.

FIGURE 3. Map of the currently known distribution of Trechus bohemorum Pawl.