Trechus strandzhensis, Kostova & Bekchiev, 2023

Kostova, Rumyana & Bekchiev, Rostislav, 2023, Trechus (s. str.) “ subnotatus ” species group (Coleoptera: Carabidae) in Bulgaria, Zootaxa 5264 (4), pp. 505-525 : 513-515

5. Trechus strandzhensis sp. n.

Type locality: Bulgaria, Strandzha Mts. , Slivarovo Vill. , along Rezovska River, “Shafariitsa” Place , N41.960506 E27.659671 .

Holotype: 1♂, Bulgaria, Strandzha Mts., Slivarovo Vill. , along Rezovska River, “Shafariitsa” Place , N41.960506 E27.659671, 08.05– 09.06.2009, R. Kostova leg. ( NMNHS), median lobe of the aedeagus dissected and mounted on a separate plate, pinned with the specimen.

Paratypes: Bulgaria, Strandzha Mts.: 4♀♀, 2♂♂, same data as holotype but 15.04– 02.07.2009 ( NMNHS) ; 1♀, same data as holotype but, 25.09.2009, R. Bekchiev leg. ( NMNHS); 1♂, Bliznak Vill., Protected Area “Bataka” , N42.193694 E27.326611, 05.05.2009, R. Bekchiev leg. ( NMNHS); 1♂, Balgari Vill., Protected Area “Marina reka” , N42.111583 E27.764722, 11.06.2009, R. Bekchiev leg. ( NMNHS); 1 ♂ Kosti Vill. Cave “ Maharata ”, N42.005505 Е27.825647, 25.09.2006, B. Petrov leg. ( NMNHS); 3♂♂, 1♀, same data as above but, 01.07.2007, leg. B. Petrov ( NMNHS); 1♂, 2♀♀, Malko Tarnovo , “Indipasqua” Place , N42.004694 E27.652556, 25.05.2009, R. Bekchiev leg. ( NMNHS); 1♂, Malko Tarnovo , “Propada” Place , N41.980445 E27.490472, 26.07.2009, R. Bekchiev leg. ( NMNHS); 1♂, Sinemorets Vill., “Butamyata” Place , N42.052861 E27.987056, 15.04- 08.05.2009, R. Kostova leg. ( NMNHS); 1♀, 1♂, Stoilovo Vill. , “Sredoka” Natural Reserve , along Mechi dol River, N42.030861 E27.513917, 23.08.2009, R. Bekchiev leg. ( NMNHS); 1♀ Gradishte Vill. 18.04.2010, leg. R. Bekchiev ( NMNHS) ; Turkey, Strandzha Mts. (= Yıldız Mts. ): 2♂, 2♀♀, Demirköy , Dökümhanesı , N41.81933 E27.81200, 30.05.2009, R. Kostova & R. Bekchiev leg. ( NMNHS); 2♂, 3♀♀, Demirköy surroundings , N41.79936 E27.73400, 06.07.2009, R. Bekchiev leg. ( NMNHS); 1♀, Sarpdere Vill., Dupnisa Cave , N41.840472 E27.556083, 29.09.2009, R. Bekchiev leg. ( NMNHS); 1♂ Sarpdere Vill., Dupnisa Cave surroundings, N41.840556 E27.556222, 01.10.2009, leg. R. Bekchiev ( NMNHS); 1♂ same data as above but, 26.05.2011 ( NMNHS) ; 1♀, Igneada , Hamam Gölü , N41.828667 E27.958639, 02.10.2009, R. Bekchiev leg. ( NMNHS)

Diagnosis: Relatively small: the body length of males is 3.5–4.5 mm, and that of females is 3.7–4.3 mm. The habitus is typical for the T. “ subnotatus ” species group, the species is wingless. The body’s dorsal surface is unicoloured brown, shiny, and slightly iridescent; the antennae, palpi, and legs are light brown. A reliable distinction from the other members of the species group could be made only by using the male genitalia. The median lobe of the aedeagus in lateral view is gradually and markedly curved, with a prolongated, well-differentiated apex. In dorsal view, the apex narrows. The apical lamella is elongated and slightly twisted to the right, separated from the remaining part by a distinct constriction. The copulatory piece is humpbacked in the proximal part and slightly concave in the distal part. The metric characteristics of the specimens from the type series are shown in Table 1 .

Description of the holotype: The habitus is typical for the T. “ subnotatus ” species group, as shown in Fig. 5 . The body length from the clypeus to the apex of the elytra is 4.2 mm.

Colour: The dorsal surface is unicoloured brown, shiny, and slightly iridescent; the antennae, palpi, and legs are paler light brown. The microsculpture consists of fine polygonal meshes that are clearly visible on the head at a magnification of 80х and reduced on the pronotun and elytra.

Head: The maximum width is at the eyes level (0.9 mm). The eyes are well developed, 1.5 times longer than the temples, head with deep frontal furrows. The antennae are moderately long and do not proceed half the length of the elytra.

Pronotum: Transverse (PW/PL=1.44), strongly heart-shaped, with the maximum width in the front one-third and lateral margins gradually narrowing to sharply protruding outward posterior angles, forming a right angle (PW/ PBW=1.35). Basal margin slightly concave laterally and slightly protruding medially. There are two marginal setae at the first anterior third and at the posterior angles.

Elytra: Oval, with slightly curved margins, wider at the last third (EL/EW=1.35). Inner striae 1–5 are clearly visible, shallow, and finely dotted, with the rest striae fading towards the margins. There are three discal setae (including the preapical one) on the third interval closer to the third stria. The umbilicate series consists of 8 setiferous pores located along the lateral margin as follows: four humeral setae at equal distances from each other, two medial setae, and two preapical setae, with a large distance between medial and preapical groups. On the apical slope there are two apical setae. The reverse apical stria is clearly visible and deep. The hind wings are fully reduced.

Male genitalia: The median lobe of aedeagus is 0.8 mm long. In lateral view, it is strongly arched. The apex is well differentiated, elongated, and directed slightly downward. In the dorsal view, the apical lamella is elongated, clearly separated by narrowing, slightly twisted to the right, and rounded at the tip. Endophallus with a clearly visible dihedral sclerotised plate—the copulatory piece—is slightly concave and saddle-shaped in the distal half; the proximal half is straight to slightly convex ( Fig. 6 ).

Etymology: The name of the species is taken from the mountain chain Strandzha, type locality and only locality known so far.

Affinities: Morphologically, the species is close to the subspecies of Т. cardioderus , based on the apex of the median lobe of the aedeagus and the coloration of the body. But it clearly differs in the shape of the copulatory piece, which is slightly concave distally in T. strandzhensis and strongly curved upward in T. cardioderus .

The species is found only in the inner part of the Strandzha Mountains. Other species of the “ subnotatus ” group with the nearest known localities are T. asiaticus (Black Sea Coast, Cape Maslen nos, Kiten and Bolyarovo Vill.) and T. byzantinus (Istanbul Distr.). T. strandzhensis is easily distinguishable from T. asiaticus by the median lobe of the aedeagus more arched in the lateral view, with the apex pointed smoothly downward versus median lobe less arched and the apex sharply curved downward in the latter species. Additionally, T. strandzhensis is smaller and has the pronotum more narrowed to the base. T. strandzhensis differs clearly from T. byzantinus in the median lobe of the aedeagus which has a distinct constriction before the apex and a rounded tip in dorsal view. Meanwhile, in T. byzantinus , the apex is slightly and gradually narrowed to the tip, which is broad and straight. In addition, the copulatory piece in the lateral view is slightly concave distally in T. strandzhensis and strongly curved upward in T. byzantinus .

Distribution and habitat: Bulgarian and Turkish part of the Strandzha Mts in leaf litter of deciduous forests, often near rivers and streams: riparian forest of Alnus glutinosa Gartn. , Quercus cerris L. with undergrowth of Lusula sp., Festuca sp. , Geranium sp. , and others; old-growth forest of Quercus hartwissiana Stev. and Q. cerris with undergrowth of Carpinus orientalis Mill. , Cornus mas L., Cornus sanguinea, Fraxinus ornis L., Acer campestre L., Fritillaria pontica Wahlenb. , Geranium sp. , and others; old-growth forest of Fagus orientalis Lipsky , single trees of Carpinus betulus L. with scarce undergrowth of Daphne pontica L., Cyclamen coum Mill. , Asperula odorata L., cereals and others; old-growth forest of F. orientalis , Q. polycarpa Schur. with thick undergrowth of Rhododendron ponticum L., single shrubs of Daphne pontica L., Ruscus hypoglossum L., Cyclamen coum, Lusula sp. and others, wind-blown coastal forests of Quercus frainetto Ten., Q. cerris with undergrowth of Ruscus aculeatus L., Asparagus acutifolius L., Symphhytum taurium Willd., Fritillaria pontica Wahlenb. , Primula acaulis ssp. rubra (L.) and others; caves surrounded by old-growth Quercus forest.

Figures

FIGURE 5. Trechus strandzhensis sp.n.: a—habitus of male paratype from “Indipasqua” Place, Strandzha Mts. Scale: 2 mm.

FIGURE 6. Variability in the median lobe of the aedeagus of Trechus strandzhensis sp.n in lateral and dorsal view (a,b— paratype: Strandzha Mts., Slivarovo Vill., along Rezovska River, “Shafariitsa” Place; c,d—holotype: Strandzha Mts., Slivarovo Vill., along Rezovska River, “Shafariitsa” Place; e,f— paratype: Strandzha Mts., Malko Tarnovo, “Indipasqua” Place; g,h— paratype: Strandzha Mts., Demirköy surroundings). Scale: 0.2 mm.