Ochthebius (Cobalius) vilanovensis, Villastrigo & García-Esquivel, 2024

Villastrigo, Adrián & García-Esquivel, Eva, 2024, Overlooked coastal habitats expose a new species: Ochthebius vilanovensis sp. nov. (Coleoptera, Hydraenidae), Zootaxa 5538 (5), pp. 439-447 : 442-443

Ochthebius (Cobalius) vilanovensis sp. nov.

Type locality. Spain, Barcelona province , Vilanova i la Geltrú, 41.21786N 1.749349E.

Type material. Holotype ♂ ( ZSM): “ Spain: Barcelona, Vilanova i / la Geltrú 26.05.2024 / 41.21786N 1.749349E / E. García & A. Villastrigo ”; with holotype label. Aedeagus dissected and mounted in the same card . Paratypes ( ZSM, CHC, AVC): 2 ♂, 7 ♀, same data as holotype, with paratype labels .

Description. Habitus as in Figure 2 . Length: 1.6–1.9 mm; maximum width: 0.56–0.70 mm. Body colour uniformly black, appendages from brown to dark brown, with lighter tibiae.

Head microreticulated and rugose; with short whitish hook-like setae; frontoclypeal suture impressed; clypeus and labrum shiny and dark brown with transparent setae; anterior margin of labrum slightly emarginated; with two fovea on vertex. Eyes large, prominent.

Pronotum with very convex side margins with dented lateral margins and anterior margin straightened; dense irregular setiferous punctures; densely covered by whitish hook-like setae; anterior and posterior margins with an expanded hyaline band.

Elytra elongated, oval; serrated margins laterally, less serrated in the distal section; regular series of punctures with short whitish hook-like setae as in pronotum. Apterous.

Short, robust legs with rows of spine-like setae plus an external row of hook-like setae on the tibiae; without natatorial setae.

Metaventrite weakly microreticulate. Abdominal ventrites (i-v) densely pubescent with thin recumbent setae and well-impressed rugose microreticulation; ventrites vi-vii with longer brownish and thicker setae on posterior margin; finer microreticulation.

Aedeagus ( Figures 2 and 3 ) with curved median lobe in lateral view, middle part slightly compressed, apex pointed. Distal lobe wide, with an approximately 90º angle on the dorsal margin and ventral margin convex, apex hyaline. Parameres inserted near the basal third of the median lobe, not reaching its apex.

Sexual dimorphism: Almost identical morphologies and body sizes in males and females. Females have a more strongly emarginated labrum than males, although the character is slightly variable and requires further study with a longer series of specimens before this apparent difference can be confirmed.

Etymology. Named after the type locality, Vilanova i la Geltrú. The specific name is an adjective in the nominative singular.

Distribution. Only known from the type locality ( Figure 4 ).

Habitat. Specimens were found in crevices close to rockpools in the supralittoral zone, often in vertical crevices with a fine humus layer.

Differential diagnosis. Members of the Ochthebius biltoni species group are morphologically cryptic, but rather strongly divergent genetically. Most have geographically isolated distributions (on the Mediterranean islands of Sicily, Malta or Sardinia), with the only previously described species inhabiting mainland areas being Ochthebius evae , along the Mediterranean coast of the Iberian Peninsula. Despite its external morphological resemblance to Ochthebius evae , the distal lobe of the aedeagus of Ochthebius vilanovensis sp. nov. is distinctly larger, with its dorsal margin forming a pronounced 90º angle, and a slight middle compression on the main piece of the aedeagus (for direct comparison see Figure 3 ). Additionally, molecular evidence delineates this species, with a divergence greater than 7.63% for COI-3, 7.44% for COI-5 and 2.46% in 16S. Nuclear genes also display differences despite their slow evolutionary pace; 5 differences for 28S and 2 differences for 18S. The new species has only 1 difference in 18S with respect to Ochthebius cortomaltese , which may point to a closer relationship, although the two species are strongly differentiated overall (see Figure 1 ).

Figures

FIGURE 1. Selected Bayesian analysis of the subgenus Cobalius. White circles on nodes for support values higher than 0.95. Blue branches represent the Ochthebius biltoni species group.

FIGURE 2. Ochthebius vilanovensis sp. nov.: (A) male habitus, (B) female habitus and (C) aedeagus in lateral view.

FIGURE 3. Comparison of the male genitalia of Ochthebius evae Villastrigo, Hernando, Millán & Ribera, 2020 (A and C) and Ochthebius vilanovensis sp. nov. (B and D).

FIGURE 4. Distribution map (A) and habitat of Ochthebius vilanovensisis sp. nov. (B and C) plus the known localities of Ochthebius evae Villastrigo, Hernando, Millán & Ribera, 2020 in Spain (red dots in Figure 3A).