Berosus quadridens Chevrolat, 1863

Deler-Hernandez, Albert, Fikacek, Martin & Cala-Riquelme, Franklyn, 2013, A review of the genus Berosus Leach of Cuba (Coleoptera, Hydrophilidae), ZooKeys 273, pp. 73-106 : 87-91

Berosus quadridens Chevrolat, 1863 stat. restit. Figures 7 a–g8e–h 11

Berosus (Anchialus) quadridens Chevrolat, 1863: 206.

Berosus quadridens : - Gundlach 1891: 47 (diagnosis and distribution). - Zaitzev 1908: 357. - Mouchamps 1963: 121 (synonymized with Berosus truncatipennis Castelnau, 1840). - Van Tassell 1966: 56 (unpublished PhD thesis: redescription, identification key). - Spangler 1981: 156 (diagnosis and distribution). - Hansen 1999: 82 (as synonym of Berosus truncatipennis ). - Peck 2005: 48 (checklist). - Deler-Hernández and Cala-Riquelme 2010: 73 (diagnosis, distribution, identification key).

Type locality.

Cuba.

Type material.

Not examined.

Additional material examined CUBA: Pinar del Río: 1 ex. (dry-mounted) (IRSNB): S of Pinar del Rio, 12/23.ix.1913. Isla de la Juventud: 7 exs. (in alcohol) (BSC-E): Punta del Este, Laguna temporal [temporal pool], 21°33'43"N, 82°33'18"W, 1 m a.s.l., 21.v.2006, leg. Y. S. Megna, 00142. Granma: 3 exs. (in alcohol) (BSC-E): Cauto Cristo, Laguna permanente-I [permanent pool-I], 20°33'33.1"N, 76°28'44"W, 44 m a.s.l., 04.i.2005, leg. L. Chávez, 00087; 1 ex. (in alcohol) (BSC-E): Cauto Cristo, Laguna permanente-I [permanent pool-I], 20°33'33.1"N, 76°28'44"W, 44 m a.s.l., 13.vi.2004, leg. L. Chávez, 00174. Santiago de Cuba: 1 ex. (in alcohol) (BSC-E): Palma Soriano, Monte Barranca, 20°20'13.5"N, 76°1'11.6"W, 203 m a.s.l., 05.xii.2007, leg. A. Deler-Hernández and B. Téllez, 00052. MEXICO: Sinaloa:1 ex. (dry-mounted) (IRSNB): Los Mochis Station, x.1921 leg. R. V. van Zwaluwenburg. Veracruz:2 exs. (dry-mounted) (IRSNB): without more detailed locality, leg. Höge. GUATEMALA: 4 exs. (dry-mounted) (IRSNB): Paso Antonio, 400 ft., leg. Champion. NICARAGUA: Chinandega: 1 ex. (dry-mounted) (IRSNB): Posoltega, 06.v.1984, UV light, leg. Algodon. COSTA RICA: Guanacaste:10 exs. (dry-mounted) (KSEM, NMPC): 11.5 km W of Cañas, 15 m a.s.l., HG light by ditch/field [AS-04-026], leg. A. E. Z. Short & D. J. Lebbin; 1 ex. (dry-mounted) (NMPC): Highway 1, 13.1 km SW of Liberia, roadside ditch/pools, 16.vi.2003, leg. A. E. Z. Short.

Published Cuban records:Cuba: Isla de la Juventud: Laguna Base Julio Antonio Mella ( Spangler 1981). Matanzas: Cárdenas ( Gundlach 1891). Holguín: Gibara, Arroyo Landivar at Finca Pozón ( Spangler 1981).

Diagnosis.

Large elongate species, body length 6.2-6.7 mm. Head testaceous with darker central part of clypeus and frons; pronotum pale, with a pair of vaguely defined narrow black longitudinal spots mesally, pronotal punctation darkened; elytra pale with dark elytral striae, interval punctation and variable number of larger dark spots on elytral intervals. Elytral apices each with a large subapical tooth, sutural angle sexually dimorphic, rounded in males, sharply pointed in females. Mesoventral process highly laminar, subtriangular in shape, anterior tooth weakly developed. Abdominal ventrite 1 with median keel developed only between metacoxae. Emargination of abdominal ventrite 5 deeply and narrowly excised in males, shallowly semicircular in females. Aedeagus large, with joint parameres pointed apically, with subbasal tuft of setae on dorsal surface, ventral membranous lobes minute, median lobe slender and long.

Differential diagnosis.

Berosus quadridens is easily distinguishable from Berosus truncatipennis by the relatively larger and more sclerotized aedeagus having stouter and relatively longer phallobase, by ventral face of parameres bearing subbasal tuft of setae (Fig. 8g) (whereas bearing a series of setae (Fig. 8c) in Berosus truncatipennis ), by relatively longer and narrower median lobe and minute membranous dorsal projections of the parameres (Figs 8e, f, h) (in contrast to moderately large ones present (Figs 8a, b, d) in Berosus truncatipennis ). The aedeagus of Berosus quadridens may resemble that of Berosus megaphallus by its large size and presence of subbasal tuft of setae on ventral face of the paramere, but both species distinctly differ by the size and proportions of the phallobase (ca. half as long as the whole aedeagus and very robust in Berosus megaphallus ; ca. third as long as the whole aedeadus and less robust in Berosus quadridens ) and by the proportions of the ventral membranous lobe of the paramere (minute in Berosus quadridens , nearly as long as paramere in Berosus megaphallus ). In general, the aedeagus of Berosus quadridens looks like an enlarged aedeagus of Berosus truncatipennis on the first view, whereas that of Berosus megaphallus clearly differs from both Berosus truncatipennis and Berosus quadridens by the general proportions of its parts. We failed to find any realiable external differences between Berosus truncatipennis and Berosus quadridens ; Van Tassell (1966) indicates the differences in the shape of the apical portion of elytra - these were found rather constant in shape in examined specimens of Berosus quadridens , but seem to be very variable in examined specimens of Berosus truncatipennis and the character seems to be therefore unrealiable for distinguishing both species at the moment. Based on the differences mentioned above, we confirm that Berosus quadridens is a valid species, distinct from Berosus truncatipennis .

Redescription.

Habitus as in Figs 7a, b. Body length 6.2-6.7 mm. Head, labrum and antennae testaceous. Maxillary palpi testaceous with palpomere 4 dark at apex. Pronotum testaceous with two metallic black central spots developed throughout pronotum. Scutellum testaceous. Elytra testaceous with oblique series of dark brown spots in posterior half and laterally, interval punctuation and elytra striae darkened. Pro- and mesofemora testaceous; metafemora with pubescent portion brown, glabrous portion testaceous.

Head and pronotum with punctures moderately fine and rounded. Elytral striae narrow well impressed. Interstriae fine and flat, bearing spine-like setae on posterior half of elytra. Scutellum with few impressed punctures. Elytral apices bidentate, each bearing a projection on sutural angle and subapically; shape sexually dimorphic, with sutural angle rounded in males (Fig. 7d), sharply pointed in females (Figs 7c). Mesoventral process highly laminar, triangular in shape, anterior tooth barely visible, followed by a convex and smooth ridge (Fig. 7e). Metaventral process raised, triangular in shape, with elongate and deep glabrous median depression; posterolateral angles produced into triangular laminae, posterior projection pointed. Abdominal ventrite 1 with median carina only between metacoxae and with large, deep, rounded lateral depressions. Abdominal ventrite 5 with a deep rounded emargination without tooth in males (Fig. 7g), in females with semicircular apical notch (Fig. 7f). Basal pubescence of meso- and metafemora covering basal two thirds of femoral length, borderline between pubescent and glabrous portion sinuate on meso- femur, straight on metafemur. Protarsus of male with adhesive soles on the two basal tarsomeres, protarsomeres 1-2 thickened, tarsomere 1 longer than tarsomere 2, tarsomere 3 elongate; tarsomere 4 elongate, as long as tarsomeres 1-3 combined. Claws long, slender and curved.

Male genitalia (Figs 8 e–h): Phallobase robust, ca. 0.4 × as long as whole aedeagus, slightly widening basad in lateral view. Parameres joint mesally, together forming a dish-like structure surrounding median lobe; apical portion rounded in lateral view, pointed in ventral view; ventral portion of each paramere with minute membranous lobe; dorsal face of each paramere with a tuft of setae situated subbasally. Median lobe stick-shaped, reaching to apical 0.75 of paremeres.

Taxonomic comments.

Described from Cuba, Berosus quadridens was considered endemic to the island, whereas the continental form was supposed to represent the widely distributed South American species Berosus truncatipennis (e.g., Zaitzev 1908, Knisch 1924). Based on two females from Cuba (one of which we reexamined in this study), Mouchamps (1963) synonymized Berosus quadridens with Berosus truncatipennis . This was questioned by Van Tassell (1966) who followed the unpublished opinion of J. Balfour-Browne and considered Berosus quadridens as a species separate from Berosus truncatipennis occurring not only in Cuba, but also in Central America. The thesis by Van Tassell (1966), and therefore the revalidation of Berosus quadridens ,remained unpublished and was only adopted without any explanatory comments in the catalogue of Cuban beetles by Peck (2005). Hansen (1999) considered Berosus quadridens as a dubious synonym of Berosus truncatipennis pending revision ( Hansen 1999). Oliva (1989) considered the size and proportions of the genitalia of Berosus truncatipennis as geographically variable, being larger and wider in subtropical areas. Recently, Oliva and Short (2012) described the specimens with the large aedeagus from Venezuela and Guyana as a separate species Berosus megaphallus Oliva & Short, 2012, but the identity of the Central American and Caribbean specimens remained unsolved.

We were not able to examine the unique type of Berosus quadridens from “Cuba”, as it was not found in MNHN after our loan request in 2012. A single species of Cuban Berosus matching the original description by Chevrolat (1863) was found in Cuba in our survey; no closely related or similar species was recorded from Cuba. We therefore do not have doubts that the Cuban specimens examined correspond to Chevrolat’s (1863) understanding of Berosus quadridens . Moreover, Van Tassell (1966) mentioned that J. Balfour-Browne has examined the type of Berosus quadridens and found it to be conspecific with Central American specimens identified previously as Berosus truncatipennis . This corresponds with our findings, as we found that all examined Central American specimens of " Berosus truncatipennis "are conspecific with the Cuban ones, and clearly differ from the South American species (see Diagnosis above for diagnostic characters).

By confirming the separate species status of Berosus quadridens , the originally widely understood Berosus truncatipennis is shown to consist of three species: the widely distributed South American Berosus truncatipennis , Berosus quadridens confined to the Caribbean and Central America, and Berosus megaphallus known so far from Venezuela and Guyana. In the material from IRSNB we examined for this study, we have found few specimens from Bolivia ( Río Beni) and southern Peru (Ica) which male genitalia are extremely similar to those of Berosus quadridens by their large size, strong sclerotization and relatively longer phallobase; however, they seem to differ from Berosus quadridens by the presence of the series of setae on the paramere (as in Berosus truncatipennis ) and the dorsal membranous lobe of the paramere being ca. as long as in Berosus megaphallus (examined only in the Bolivian specimen, indistict in dissected Peruan ones). We suppose that these specimens may represent yet another undescribed species of the formerly broadly understood Berosus truncatipennis .

Habitat.

The Cuban specimens examined in the present work were collected in highly exposed freshwater pools with turbid water, muddy bottom and without cover vegetation. Gundlach (1891) also reports this species from permanent ponds in the Matanzas Province.

Distribution.

Based on the specimens examined for this study, we may confirm the occurrence of Berosus quadridens for Mexico, Guatemala, Nicaragua, Costa Rica and Cuba. Van Tassell (1966) also maps one record from Panama, but does not cite label data. In Cuba, the species is known from the western (including Isla de la Juventud special municipality) and eastern regions.