Vatellus ventralis Miller, 2005

Miller, Kelly B., 2005, Revision of the New World and south-east Asian Vatellini (Coleoptera: Dytiscidae: Hydroporinae) and phylogenetic analysis of the tribe, Zoological Journal of the Linnean Society 144 (4), pp. 415-510 : 452-454

VATELLUS VENTRALIS (SHARP, 1882) COMB. NOV.

Macrovatellus ventralis Sharp, 1882b: 285 ; Zimmermann, 1920: 30; Trémouilles, 1995: 27.

Type information: Holotype (by monotypy) ♀ in MNHN labelled, ‘[small, light purple square]/Haag [handwritten, black line around label]/Brazilia [handwritten, green label with black line around border]/ HOLOTYPE Macrovatellus ventralis Sharp, 1882 [red label with black line border].’ Sharp (1882b) had a single specimen that he apparently borrowed from Wehncke. Wehncke’s specimens are in the MNHN. A single specimen was found among the MNHN vatelline material that matches Sharp’s description of the species (including the absence of tarsi) and is apparently a Wehncke specimen since it is labelled exactly the same as the type of V. haagi Wehncke. Therefore, I have concluded that it must be the holotype of this species.

Type locality: Brazil .

Diagnosis: This species may be distinguished from other Vatellus by the following combination of characters: (1) dorsal and ventral surfaces alutaceous, elytra with punctures and fine microreticulation between them; (2) eyes moderately large, not strongly protruding ( Fig. 109 ); (3) transverse pronotal crease indistinct; (4) apical lobe on abdominal sternum VI very large, flat, apically rounded ( Fig. 113 ); (5) anterior clypeal margin produced into distinct anteriorly directed rim; (6) pronotum prominently cordate, lateral margins strongly sinuate; and (7) ventral surface of dorsal margin of orifice to speleum with small, but prominent, longitudinal carina, dorsal surface of ventral margin distinctly bilobed to fit over dorsal carina. This species is similar in many respects to V. grandis and similar species because they are elongate, evenly coloured, dorsoventrally flattened and have the anterior margin of the clypeus distinctly produced. However, in V. ventralis the dorsal surfaces are alutaceous, the punctation is moderately fine and evenly distributed on the head and pronotum, the anteromedial margin of the metasternum is not swollen, and the female receptacle is relatively large. Also, in other species of Vatellus the ventral surface of the dorsal margin of the orifice to the speleum has a cavity that receives a corresponding prominence on the dorsal surface of the ventral margin. Vatellus ventralis has a longitudinal, sharp carina on the ventral margin and a bilobed prominence on the dorsal margin. The dorsal lobe is extremely thick and has an apical, posteriorly directed prominence as well. These characters are subtle, but they make V. ventralis unique.

Description:

Habitus. Lateral outline strongly discontinuous in dorsal aspect, lateral elytral margins moderately rounded ( Fig. 109 ), distinctly dorsoventrally flattened. Measurements are given in Table 1.

Coloration. Head brown; pronotum brown; elytron brown, immaculate ( Fig. 109 ); venter and appendages brown.

Sculpture and structure. Head with punctation distinct, small, dense, evenly distributed over entire surface except posterior quarter, interpuncture surfaces prominently microreticulate, surface posterior to eyes alutaceous, rough, slightly swollen; anterior clypeal margin anteriorly produced; eyes moderately large, somewhat protruding. Pronotum densely punctate, punctures moderately large, pale setae inconspicuous; pronotum strongly cordate, lateral pronotal margin rounded anteriorly, broadest near anterior angles, posterior angles acute ( Fig. 109 ); lateral bead obscured; transverse sulcus slightly impressed; surface alutaceous. Elytron with punctation moderately dense, punctures moderately large, interpuncture surfaces prominently alutaceous, pale setae inconspicuous, surface similar to pronotum ( Fig. 111 ). Prosternum short, roughly sculptured, glabrous; prosternal process broad with distinctly rounded medial carina, lateral margins rounded, apex moderately triangularly produced, glabrous, apex obtusely pointed. Metasternum with punctation fine and sparse, obscured by alutaceous surface sculpture; anteromedial margin not produced ventrally. Abdominal sterna sutures not unusually modified; sterna with punctation sparse and fine, obscured by surface sculpture; sixth abdominal sternum with apical lobe very large, broad, flattened, apically rounded ( Fig. 113 ); speleum broad basally, narrowed and parallel sided, apically narrowly rounded ( Fig. 114 ). Metacoxae with lateral portion moderately punctate over entire surface, punctures shallow, somewhat obscured by alutaceous sculpturing; metacoxal lines approximate posteriorly, strongly divergent anteriorly ( Fig. 110 ); medial portion moderately punctate, punctures finely setose. Metatrochanter rounded, strongly offset ( Fig. 112 ); metatarsal claws dentate.

Female genitalia. Gonocoxosternite broad, robust, medial margin broad, apical angle about 90∞; anterior margin concave; anterior lobe moderately long, narrow ( Fig. 115 ). Gonocoxa moderately broad, subtriangular, apodeme moderately narrow, longer than main portion, numerous setae along apicoventral margin and on dorsal surface ( Fig. 115 ). Bursa copulatrix moderately small, with two anterior lobes, one on each side; spermathecal duct relatively long, slender; receptacle spherical, slightly smaller than spermatheca; intermediate duct short, sinuate ( Fig. 116 ); spermatheca nearly spherical, triangular process broad; fertilization duct short, curved ( Fig. 115 ).

Distribution: This species is known only from the type locality, ‘Brazil’.

Phylogenetic relationships: This species occupies an unresolved, basal position within Vatellus ( Fig. 316 ). The lack of information about male character states undoubtedly contributes to its alternative placements in the most parsimonious trees, but it also lacks some of the more distinctive characters used to group taxa within Vatellus .

Material examined: Only the holotype was examined of this species.

Figures

Figures 109–114. Vatellus ventralis. 109, dorsal habitus; 110, medial portion of metacoxae; 111, elytral sculpture in area indicated on habitus by dotted square; 112, left metatrochanter and metafemur, anterior aspect; 113, sternum VI, ventral aspect; 114, speleum abdominal sterna V, VI, dorsal aspect.

Figures 115–116. Vatellus ventralis. 115, female genitalia, ventral aspect; 116, spermatheca and associated structures, dorsal aspect.

Figures 315–316. Vatellini species, consensus cladograms. 315, Consensus cladogram of 72 most parsimonious cladograms (length = 78, CI = 67, RI = 92) resulting from cladistic analysis of Vatellini including Calicovatellus petrodytes. 316, Consensus cladogram of five most parsimonious cladograms (length = 74, CI = 70, RI = 93) resulting from cladistic analysis of Vatellini not including Calicovatellus petrodytes. Numbers above branches are Bremer support values.