Petraphaenops, 2020

Delić, Teo, Kapla, Andrej & Colla, Andrea, 2020, Orogeny, sympatry and emergence of a new genus of Alpine subterranean Trechini (Coleoptera: Carabidae), Zoological Journal of the Linnean Society 189, pp. 1217-1231 : 1222-1226

PETRAPHAENOPS DELIĆ ET AL. , gen. nov.

urn:lsid:zoobank.org:act:AC14ED47-6530-4921-93C4-4CDEA055F5EE

Type species: Petraphaenops unguiculatus sp. nov., here designated.

Etymology: The generic name is composed of the Greek πέτρα, petra rock, and ‘ Aphaenops ’, name of the famous Pyrenean trechine genus, which represents a classical example of troglomorphic subterranean Carabidae and defines the so called ‘ type aphénopsien’ (Jeannel, 1926) morphology.

Diagnosis: Anophthalmous genus of trechine ground beetles, medium-sized (type length 6.11 mm), pale brown, shiny, characterized by an aphaenopsian habitus, showing a high degree of troglomorphism. The head as wide as the pronotum, both proportionally thinner than in the closely related Aphaenopidius , with six supraorbital setae. Pronotum hairless, without setae in the anterior marginal position and in the posterior angles. Elytra elongated, without humeral shoulders, with all the umbilicate setigerous pores aligned in an arch along the marginal gutter, and two discal setae. Tarsi with disproportionally long claws, about twice or more as long as in Anophthalmus or other average to large-bodied trechines. Aedeagus elongated, similar to that of Aphaenopidius , but thinner and less curved in the median lobe, with its axis forming almost a right angle with that of the basal lobe. Isotopic copulatory piece, anteriorly bilobate ( Figs 5-9). Known only from the type species.

Description: Medium-sized genus of subterranean trechines, blind, with a high level of troglomorphism; body elongated, glabrous, with head as wide as the prothorax, the latter short, elytra without humeral angles; legs extremely long, especially the femurs, tarsi with claws indicating specialization to a specific ecological niche within the cave environment – presumably cave hygropetric; posterior wings absent; depigmented, colour pale brown, almost amber, shiny. Head as wide as the pronotum, elongated but robust, about twice as long as wide with closed mandibles included, with the maximum width at level of a section between the anterior and intermediate supraorbital setae, progressively narrowing to its posterior part and neck, without prominent temples (the cuticle between the ocular region and neck); neck robust and wide but elongated, with a large articular surface between the neck constriction and the pronotal anterior margin (with the head in the same axis as the body); frontal furrows well marked, but incomplete, parallel, suddenly stopping at the level of the intermediate supraorbital setae; head surface glabrous, with six supraorbital setae (three on each side), the front pair at the level of half the length of the frontal furrows, the middle pair equidistant from the clypeofrontal suture and the neck constriction; the hind pair of setae at level of the temples; eyes totally absent; vertex frontally convex; clypeus with the anterior margin weakly convex, with a glabrous central area between the setae, that are two or three on each side (character asymmetrical in the holotype); labrum concave in the middle, bilobate, normally sexsetose; mandibles long and robust, gently curved in the middle, then arcuate at the acute apex, bidentate in the molar region; maxillae almost as long as the mandibles; maxillary palps long, thin, the penultimate and ultimate articles each as long as half of the third antennomer, the ultimate in the shape of a narrow bowling pin; antennae reaching about 84% of the total body length, with the scapus more than twice as long as wide, the second article almost four, the third, fourth and the fifth article about ten, the sixth and seventh article more than eight, the eighth and ninth more than six, and the tenth and 11 th article almost six times longer than wide. Prothorax small, thinner than a single elytron, less than a third of the maximum body width at elytral level, about as long as wide, round-ovate, with shallow and narrow marginal gutters; regularly arched lateral margins, barely sinuated in correspondence to the small anterior and posterior lobes, the later with rounded hind angles; front angles more acute anteriorly, as a consequence of the concavity of the pronotal front margin, resembling a widely open ‘V’; hind margin shorter than the front one, only slightly concave; transverse sulcus present; disc convex, shiny, glabrous, without any visible setae or setigerous pores, apart from three asymmetrically inserted setae near the anterior margin. Elytra elongated, slightly longer than half of the total body length, pair of elytra approximately 1.8 times as long as wide, maximum width slightly behind middle, at the level of the third discal setigerous pore; surface flat in the first third, moderately convex in the central and apical part, with shallow but still recognizable inner striae, external ones almost vanishing; oblique prehumeral margins, almost straight or only slightly concave, gently connected with the arched posthumeral margin, without humeral angles; elytral chaetotaxy with all the pores of the umbilicate marginal series close to the marginal gutter; first four pores in the humeral region, more or less equidistant from each other; the fifth pore at the level of the second discal or slightly anterior (the holotype is asymmetrical), in a slightly inner position; the distance between the fifth and the sixth pore the same as the distance between the third and fourth; the seventh pore distally three times that distance; the basal setigerous pore present; two discal setigerous pores on the third stria, the second about at the level of the maximum elytral width; the front pore of the apical triangle distant backwards; a shallow apical carina; elytral suture posteriorly divergent, with a small pointed apical protrusion on each elytron. Legs long, especially the femora and tarsi; the anterior tibiae not sulcate; long pubescence on the external distal third of the femora and on the tarsi, shorter and less dense on the tibiae; male protarsi with the first two tarsomeres dilated; tarsal claws developed, long and slender, slightly arcuate. Aedeagus well sclerotized, elongated, similar to that of Aphaenopidius , but thinner, tubular, with the median lobe almost straight, its axis forming an almost right angle with that of the basal bulb, apex short and folded upwards; styles with four stout setae in the apex; inner sac with thorny scales, armed with a small isotopic copulatory piece, sclerotized, bilobate, comprising two branches basally fused and frontally divergent, giving the copulatory piece the shape of a narrow ‘V’. The branches are kept parallel and adherent to each other in retracted position inside the inner sac.

Remarks: From the morphological point of view, characters like the three pairs of supraorbital setae, the absence of humeral angles, the genitalia, etc., suggest that Petraphaenops is a new genus related to the syntopic Aphaenopidius Müller, 1913 , a narrowly distributed, large aphaenopsian genus of isotopic trechine. However, the presently known Aphaenopidius taxa are incomparably larger in size, macrocephalic, with a transverse pronotum clearly wider than it is long and heart-shaped because of the distinct and sinuate lateral margins, with four pronotal setae normally positioned. According to these differential characters and the original description by Müller (1913), the new taxon cannot be included in that genus. Petraphaenops is easily distinguishable from Aphaenopidius being about half its size, with a thinner head and pronotum, the last totally different in shape and lacking any pronotal setae. This complete lack of setae is not only a differential character from Aphaenopidius , but it is generally unusual among southern calcareous Alpine and Dinaric Trechini . Moreover, the general shape of the aedeagus resembles also that of some Duvalius s.l. and Anophthalmus species. The isotopic copulatory piece also resembles that of Aphaenopidius spp. and of some Duvalius s.l.

These morphological considerations agree with the genetic ones.

PETRAPHAENOPS UNGUICULATUS DELIĆ ET AL., SP.