Trechus terrabravensis Borges, Serrano and Amorim, 2004

Borges, P. A. V., Serrano, A. R. M. & Amorim, I. R., 2004, New species of cave-dwelling beetles (Coleoptera: Carabidae: Trechinae) from the Azores, Journal of Natural History 38 (10), pp. 1303-1313 : 1304-1306

Trechus terrabravensis Borges, Serrano and Amorim , new species

( figure 1 )

Diagnosis

Dark pigmentation, with some lighter parts; normal and convex eyes; wingless; lateral furrows of pronotum narrower than other Azorean species. Integument wellpigmented with pronotum darker than elytra. Appendages less pigmented (light brown), with tibiae and tarsomeres darker than femora. First antennomere slightly brown and the remaining darker. Epipleura light brown and abdomen brown. Subnitidous with pronotum and head brighter. Microreticulation isodiametric on the head, but transverse on the pronotum and on the elytra.

Type series HOLOTYPE: „, Açores, Terceira, Terra-Brava , 18 July–2 August 2001 (P. A. V. Borges and F. Pereira) . PARATYPES: 2””, same locality as holotype, 5–19 May 1998, 1–15 August 1998 (D. Silva) .

Note. In addition one male and four females were collected in the same locality for molecular analysis. These are also used for measures. Additional specimens were recently collected in another locality at Terceira (Caldeira da Serra de Santa Bárbara).

Description

Length of holotype: 3.85 mm. Length of remaining specimens: 3.36–3.76 mm. Medium size, convex and ovalate.

Head almost 1.13X as wide as long, 0.76X narrower than pronotum; eyes welldeveloped, convex, diameter of eyes 2.4X larger than temples; temples with microchaetae. Frons highly convex, the frontal furrows deeply curved and rounded, with darker pigmentation. Anterior margin of labrum very concave. Maxillary palpi long and slender. Chaetotaxy: two pairs of supraocular setae; four setae in clypeus (outer ones larger); six setae on labrum, the outer ones being the largest. Antennae 2.05 mm long (others: 1.80–1.98 mm), surpassing only the first quarter of elytra; the 3rd antennomere subequal to the 2nd; 1st to 6th antennomere 2X longer than wide, 7th antennomere 1.66X longer than wide, 8th to 10th antennomere 1.3X longer than wide, 11th antennomere 2.36X longer than wide. Pronotum convex, cordiform, highly transverse, 1.29X as broad as long (others: 1.27–1.35X); side margins curved till hind angle; anterior angles obtuse; hind angles obtuse, well marked and not protruding; basal border emarginated; lateral furrows narrower than in the other Azorean Trechus ; basal fovea well marked. Chaetotaxy: the anterior setae is located in anterior quarter and the posterior seta located in the hind angle. Elytra ovate with rounded shoulders, 1.58X wider than pronotum (others: 1.48–1.60X) and 1.44X as long as broad (others: 1.35–1.48X); apex rounded, lateral furrows canaliculated; striae all well marked and interstriae convex. Recurrent striae well connected to the 5th. Chaetotaxy: umbilical series typical of Trechus ; preapical seta equidistant of suture and apex; the first discal seta in the 3rd stria is located in the anterior quarter and the second discal seta approximately in the centre.

Aedeagus with apex of median lobe straight and pointed (lateral view) ( figure 1a ); apex rounded (dorsal view) ( figure 1c ). Left and right parameres with four and five setae each, respectively ( figure 1b ).

Ecological notes

All specimens were collected by means of pitfall traps baited with Turquin (a mixture of dark beer with preservatives) or liver, located deep inside very humid laurel forests on Terceira. More recently, several specimens were collected in leaf litter, suggesting that this is a litter species. In both Terra-Brava and Caldeira da Serra de Santa Bárbara, the terrain is basaltic with a system of cracks and deep holes and the forest floor is covered by a dense carpet of mosses and ferns with little light reaching the ground.

Taxonomic notes

The aedeagus of this new species clearly resembles those of the cavernicolous troglobitic species Trechus jorgensis (S. Jorge) and T. pereirai n. sp. (Pico).

Figures

FIG. 1. Aedeagus of Trechus terrabravensis n. sp. (a) Median lobe, lateral view; (b) left and right parameres; (c) median lobe, dorsal view. Scale: 0.4 mm.