Diaphanosoma bergamini Paggi

Elías-Gutiérrez, Manuel, Kotov, Alexey A. & Garfias-Espejo, Tania, 2006, Cladocera (Crustacea: Ctenopoda, Anomopoda) from southern Mexico, Belize and northern Guatemala, with some biogeographical notes, Zootaxa 1119, pp. 1-27 : 7

Diaphanosoma bergamini Paggi & da Rocha, 1999 ( Figs. 2–8 )

Material examined: Many parthenogenetic females from Silvituc lagoon.

Body 0.60–0.70 mm, elongate. Head small, slightly directed downward. Second antenna almost reaching posterior margin of valves ( Fig. 2 ). Ventral margin of valves with a wide inflexion, armed with several thin setae ( Fig. 3 ). A dorsal spine with long setules near posterior margin of valves ( Fig. 4 ). Antennal setae 4–7/0–1–4, spines 1–1/0–1–1 ( Fig. 5 ). Rows of fine spinules on lateral side of postabdomen. Postabdominal claws armed laterally with two rows of fine denticles ( Fig. 8 ) and three long spines on the base, two of them wavy.

Diaphanosoma bergamini was described from the Amazon and Orinoco basins in Venezuela (Paggi & da Rocha, 1999), under the generic name Neodiaphanosoma Paggi & da Rocha, 1999. This genus was based on a numerical phenetic analysis, and supported mainly by the presence of a long finger­like sensillum at the tip of two­segmented antennal branch ( Fig. 5 , arrow). However, we agree with Korovchinsky (2004) that separation of the genus Neodiaphanosoma is not justified, because all characters proposed to support the genus Neodiaphanosoma are present in other species of the genus Diaphanosoma , and the only specific feature is the presence of the finger­like seta.

Silvituc is the northernmost locality of this rare species, which is closely related to Diaphanosoma volzi Stingelin from the Old World. According to Paggi & da Rocha (1999), both taxa have restricted their distribution to the tropics and subtropics, but apparently some other unknown factors limit their distribution inside this geographical range, at least for D. bergamini , since we have not detected it in any other system in the studied region. It was co­existing with Diaphanosoma brevireme Sars , a much more common species in this area.

Figures

FIGURES 2 – 8. Diaphanosoma bergamini, parthenogenetic female from La Esperanza 1 lagoon; 2) Lateral view; 3) Ventral flap and posterior margin of valves; 4) Spine on dorsal side near posterior margin of valve; 5) Second antenna, lateral view; 6) Distal part of basal segment of A 2; 7) Distal side of first segment of upper 2 ­ segmented branch; 8) Postabdomen and claws.