Berosus chevrolati Zaitzev, 1908

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 : 75-77

Berosus chevrolati Zaitzev, 1908 Figures 1 a–g 1112a

Berosus aculeatus Chevrolat, 1863: 207 (primary homonym of Berosus aculeatus LeConte, 1855). - Gundlach 1891: 48 (diagnosis and distribution).

Berosus (s.str.) chevrolati Zaitzev, 1908: 358 (replacement name for Berosus aculeatus Chevrolat, 1863). - Van Tassell 1966: 169 (unpublished PhD thesis: redescription, identification key). - Spangler 1981: 155 (diagnosis and distribution). - Hansen 1999: 84 (catalogue). - Peck 2005: 48 (checklist). - Epler 2010: 12.24 (notes on distribution).

Type locality.

Cuba.

Type material examined.

Holotype: female (MNHN): "aculeatus / Ch. Cuba // this must be / Chevr. unique type of aculeatus / PJS [= P. J. Spangler] 1966".

Additional material examined.

CUBA: Santiago de Cuba: 3 exs. (dry-mounted) (NMPC): Dos Caminos, stream, 20°11'2.50"N, 75°46'17.7"W, 150 m a.s.l., 01.viii.2008, leg. A. Deler-Hernández., 1 ex. (dry-mounted) (BSC-E): El Vivero, 1.6 km E of Dos Caminos, 20°11'2.50"N, 75°46'17.7"W, 150 m a.s.l. Guaninicú river, 20-21.vi.2012, leg. Deler-Hernández & Fikáček; 1 ex. (in alcohol) (BSC-E): La Maya, Cuatro Caminos, remanso [backwater] 20°07'58"N, 75°34'01"W, 150 m a.s.l, 24.i.2008, leg. Y. S. Megna, 00019.

Published Cuban records:Pinar del Río: Quemado de Pineda ( Spangler 1981). Matanzas: Este de Matanzas [Eastern Matanzas], Río Canimar (Gundlach, 1891). Camagüey: Río El Manantiales ( Spangler 1981). Sancti Spíritus: Río Caburny ( Spangler 1973); Arroyo Vega Grande ( Spangler 1973). Santiago de Cuba: Contramaestre, Pozo Caliente, Río Contramaestre ( Spangler 1981); II Frente, Arroyo Jarahueca ( Spangler 1981); II Frente, Sabanilla, Río Mayarí ( Spangler 1981); Río Ceiba ( Spangler 1981); III Frente, Matías, Río Mogote ( Spangler 1981). Guantánamo: La Tinta, Río Baracoa ( Spangler 1981); Baracoa, Río Miel ( Spangler 1973); Niceto Peréz, Arroyo de los Berros ( Spangler 1981).

Diagnosis.

Small, widely elongate species, body length 3.6-4.6 mm. Head dark, metallic; pronotum pale, with median unpaired narrow black longitudinal spot mesally, pronotal punctation not darkened; elytra pale with irregular small dark spots in posterior half of elytral intervals. Elytral apices each without subapical tooth. Mesoventral process highly laminar, square-shaped, with large anterior and posterior teeth. Abdominal ventrite 1 with median keel throughout its length. Emargination of abdominal ventrite 5 rectangular with a median teeth. Median lobe of the aedeagus with short basal projection and rounded apex in lateral view.

Differential diagnosis.

Berosus chevrolati resembles Berosus trilobus (with which it may even co-occur) by the small strongly punctate body, metallic head, presence of an unpaired dark spot on the pronotum, mesoventrite with hooded anterior tooth, median keel developed throughout abdominal ventrite 1, emargination of abdominal ventrite 5 rectangular with single median tooth and the median lobe of the aedeagus with long basal lobe projecting far posteriad and enlarged apical portion in lateral view. It differs from Berosus trilobus by the narrow central dark spot on the pronotum (dark spot is large and trilobate in Berosus trilobus ), elytra more evenly convex (subapical area of each elytra forms a bump in Berosus trilobus ), shortbasal projection of the median lobe (long in Berosus trilobus ) and, rounded apex of the median lobe in lateral view (apex is beak-shaped in lateral view in Berosus trilobus ).

Redescription.

Habitus as in Figs 1a, b. Body length 3.4-4.6 mm. Body short and wide, moderately convex. Head black with metallic sheen, labrum black. Antennae testaceous. Maxillary palpi testaceous with palpomere 4 brown at apex. Pronotum testaceous with a central elongate metallic spot. Scutellum black with metallic sheen. Elytra testaceous with small brown spots without discrete borders. Pro-, meso- and metafemora testaceous, basal portion of metafemora sometimes slightly darker.

Head with moderately large and rounded punctures. Pronotum with punctures of the same size as on head. Scutellum with a few deeply impressed punctures slightly smaller than those on the pronotum. Elytral striae well-impressed. Interstriae with small and shallow punctures, irregular long setae on posterior half of elytra; spine-like setae absent. Elytral apices entire and rounded, of same shape in males and females. Mesoventral process highly raised, square-shaped, with hood-like anterior tooth, posterior tooth moderately large (Fig. 1c). Metaventral process wide, slightly raised, square-shaped, with large, deep glabrous rhomboid median depression; posterolateral angles raised and rounded, posteromesal projection carinate. Abdominal ventrite 1 with median carina throughout its length. Abdominal ventrite 5 with deep rectangular emargination, bearing a broad median tooth (Fig. 1g). Basal pubescence on basal 0.7 of meso- and of metafemora, the margin between pubescent and bare portions sinuate. Protarsus of male with adhesive soles on the first basal tarsomeres, first and second tarsomere distinctly thickened, third tarsomere very slightly thickened, fourth tarsomere elongate, almost as long as tarsomeres 1-3 combined. Claws moderately long, slender, arcuate.

Male genitalia (Figs 1 d–f): Phallobase ca. 0.6 × total length of aedeagus. Parameres in lateral view wide basally, apically projecting into rounded apex slightly bent ventrad, bearing a row of subapical setae ventrally. Median lobe C-shaped in lateral view; basal projection short, directing apicad; apex wide and rounded in lateral view.

Distribution.

Currently only known from Cuba. Spangler (1981) recorded this species from several localities across the island, but all new material is from two sites in Santiago de Cuba province.

Habitat.

We collected Berosus chevrolati along the margins of lowland streams and in isolated pools along these streams, in both cases having clear to turbid water and abundant organic matter (Fig. 11a). This species is found at low altitudes (ranging from sea level to ca. 160 m a.s.l.) situated in the Central Valley (Valle Central). Berosus chevrolati is frequently associated with Berosus trilobus in those habitats. Spangler (1981) also collected the species in standing waters.