Grimaldina brazzai Richard, 1892

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 : 11-13

Grimaldina brazzai Richard, 1892 ( Figs 15–25 )

Material examined: +20 parthenogenetic females from Silvituc, Campeche ( Mexico), three females from La Democracia ( Belize).

This species was also mentioned by Garfias­Espejo & Elías­Gutiérrez (2004) but here we include a brief description, including some SEM microphotographs as a reference for future studies.

Body 0.73–0.85 mm, subovoid, with posterior margin convex ( Fig. 21 ). Ventral margin of valve covered in the first two thirds by lanceolate setae ( Fig. 23 ), widest in the middle, and the last third with smaller aciculate setae ( Fig. 24 ). Surface of valves with a uniform squamose appearance forming concentric lines in the whole length of the body ( Fig. 21 ) being especially distinct on the head shield. Head shield lacks a dorsal head pore ( Fig. 22 ). Antennule rod­like, with 6–8 transverse rows of small spinules ( Figs. 29, 30 ), ending in a series of spine­like projections surrounding the distal margin. Nine aestethascs of different length. Second antenna with spine formula: 0–1–0–1/0–0–1, and setal formula: 0–0–1–3/1–1–3 ( Fig 31 ). Postabdomen bilobed ( Fig 25 ), its proximal part compressed laterally and bordered by a double row of small spinules ( Fig. 26, 27 ). Anal region not as compressed as proximal part of postabdomen, with anus subterminal, bordered by a row of strong spines ( Figs. 28 ), and a solitary large anal tooth on proximal side. Postabdominal claw strongly chitinized, with two rows of spinules along concave margin, the internal row with small and external row with larger spinules. Two basal spines of different size ( Fig. 28 ).

G. brazzai is a rather rare cladoceran, hard to find in samples from the tropics, and always represented only by 1­ 2 specimens. It was described from Congo ( Richard, 1892). Since then it has been observed in some tropical regions, including Central and South America, Australia ( Smirnov, 1992), and Africa (Kořínek, 1984). Sars (1901) obtained specimens from dried mud collected in Brazil. Recently the species was analyzed by Silva­ Briano (1998) and Hollwedel et al. (2003). In Mexico G. brazzai was previously recorded only from the southeastern part (Elías­Gutiérrez et al., 1999; Garfias­Espejo & Elías­ Gutiérrez, 2004). In all cases they are represented by few specimens, sometimes by only one. We collected a good number of females of a population from Silvituc. Because the distribution is so wide, it is possible that this species represents a species complex, but this requires further studies.

Figures

FIGURES 15 – 20. Thoracic limbs of Macrothrix spinosa. Numbers for setae follow Kotov et al. (2004). 15) Limb I, endopodite 1 ­ 3; 16) Limb I, ODL and IDL; 17) Limb II, exopodite; 18) Limb III, exopodite; 19) Limb IV; 20) Limb V.

FIGURES 21 – 31. SEM of Grimaldina brazzai, population from Silvituc, Mexico. 21) Lateral view; 22) Head shield, dorso­anterior view; 23) Ventral margin of valve, anterior side; 24) Ventral margin of valve, posterior side; 25) Distal side of postabdomen with claws, lateral view; 26) Proximal side of postabdomen, lateral view; 27) Detail of marginal spines on proximal side of postabdomen; 28) Postabdominal claws, dorsal view; 29) Tip of A 1; 30) A 1, antero­vental view; 31) A 2, endopod and exopod.