Hydrochus cf. obtusicollis, Fairmaire, 1877

Benamar, Loubna, Bennas, Nard, Henegouwen, Arno Van Berge, García-Meseguer, Antonio José, Hassoun, Mustapha, Benali, Naouar & Millán, Andrés, 2024, The Hydrochidae (Coleoptera) of Morocco with a redescription of Hydrochus cf. obtusicollis Fairmaire, 1877, Zootaxa 5458 (2), pp. 197-228 : 202-203

Redescription of Hydrochus cf. obtusicollis

Hydrochus cf. obtusicollis Fairmaire, 1877: 141

Type locality: “ Morocco ”.

Type material: We were unable to confirm that Hydrochus cf. obtusicollis is the same taxon that Fairmaire described under this name, since, despite our efforts, we have not been able to locate the types, which appear to be lost. As a consequence, we refer to this distinct North African taxon as H. cf. obtusicollis here.

Material examined: 2 ♂♂ “ Morocco, Chefchaouen , 2.04.2018; Rif, on the road to Fifi// Large crowfoot (Ranunculus) pond with muddy edge and oak leaves// N 35° 1.398’ W 5° 12.417’ // G. Foster and S. Foster leg.” (Abdelmalek Essaadi University, Tetuan) ; 1 ♂ “ Morocco, Chefchaouen , 2.04.2018 // Rif, Bab Berred (or BabBerret). Large pool// N 35° 1.130’ W 4° 59.963’ // G. Foster and S. Foster leg.” (Abdelmalek Essaadi University, Tetuan) ; 1 ♂ “ Morocco, Tétouan , 8.02.1931, Smir.” (Natural History Museum, London) .

Redescription. Habitus as in Fig. 2A . Body length (front of labrum to elytral apices) 4.0–4.2 mm, elongate shape, body colour black with metallic reflects.

Head: Black shining, with deep, sparse, and irregular punctuation; micropunctures also irregularly distributed, many of the micropunctures with setae. Antennae and maxillary palpi brown dark; apex of the last segment of maxillary palpi black.

Pronotum: Black shining, with a large round discal depression, two smaller, round, contiguous depressions in the posterior half, and two elongated depressions along lateral sides, deeper anteriorly; surface with similar punctation and micropunctation as on the head, coarse punctures more regularly distributed than on the head. The two lateral edges of the pronotum are crenellated, and the denticles are lighter on the mesoposterior side.

Scutellum : Rectangular with a rounded edge.

Elytra: length: 2.9–3.1 mm, width: 1.1–1.2 mm. Elongate, black, abruptly expanded to the humeral angle, then parallel sided to a quarter of the way from the apex, where they are constricted to just before the apex, which is truncate; regular punctuation with ten lines in each elytrum, interstices finely punctuated; the striae are a little finer apically, and the inner apical angles have one larger puncture followed by a transverse one.

Legs: Uniform, dark like the pronotum and elytra with femur bearing fine hairs and the last tarsal segment elongate and gradually dilated toward the apex, which is black and bearing fine hairs.

Aedeagus: In dorsal view ( Fig. 2B, C ), presents a tubular and thin median lobe, curved to the left, without flagellum, and shorter than parameres. The parameres are dissimilar, being the right paramere bisinuate towards the left as is the median lobe. The left paramere presents a characteristic bisinuate shape, with the external lateral apex with three characteristic invaginations, ending with a sub-arched apex.

Differential diagnosis. Hydrochus cf. obtusicollis can be distinguished from H. flavipennis by the following features: body strongly elongated with parallel margins, the base of the pronotum as broad as the base of elytra, body darker with metallic lustre, larger size ( H. flavipennis size average: 2.8–3.6 mm); the denticles of the posterior part of the pronotum are more pronounced than those of H. flavipennis . This species can be also differentiated from H. angustatus by the metallic reflections of its body, smaller apical punctures of the elytra, and a wider pronotum. The aedeagus of H. cf. obtusicollis is also clearly different to that of H. flavipennis ( Fig. 3A ), and more similar to H. angustatus ( Fig. 3B ), differing by a more curved shape of the median lobe, the distinct right paramere, and the three sinuosities at the apex of the left paramere.

Ecology: Sites supporting this species are characterized by their stagnant character, their strictly silty substrate, mixed with plant debris, and by water with limited mineralization (50-450 µs / cm). In the case of the Ras el Ma (Jbel Ouetka) spring, the impoundment area is very small in extent (0.75 m 2) and depth (5 cm), that of Fifi is a little larger, around 1.5 m 2, whilst Anasar bog exceeds 50 m 2, of which more than 50% is covered by sub-submerged macrophytes.

Figures

FIGURE 2. Hydrochus obtusicollis. A) Habitus; B–C) Male genitalia in dorsal view.

FIGURE 3. Hydrochus aedeagi, ventral view:A) Hydrochus flavipennis; B) Hydrochus angustatus; C) Hydrochus tariqi; D) Hydrochus obtusicollis; ventral and lateral views: E–F) Hydrochus aljibensis; G–H) Hydrochus smaragdineus; I–J) Hydrochus grandicollis; K–L) Hydrochus nitidicollis.