oblong, with 5-9 short setae, and genital plate transversely oval with 14-20 short setae.
a) Posterior view of Tonicia fremblyana from Peru, with the last intermediate plate (red arrow), fused with the anal plate
(black arrow), b) dorsal view of Chiton magnificus, with a reduction of the IV plate (red arrow), and c) dorsal view of the posterior end of Plaxiphora mercatoris with hypomerism, the broken plates reveal the impression on the mantle for the last intermediate plate (red arrow) and the anal plate
Preopercular pores arranged in a small compact group of 14-19 pores present anterior of anal plates
, with another small group of 11-19 pores dorsad to a point midway between antennal bases.
Remarks: The specimens reported here have striated anal plate
lobes as those described by Rao and Ganapati (1967), Westheide (1967) and Hulings (1971); contrasting to the specimens described by Vieitez et al.
It is different from Achradocrinus in the conical rather than rounded cup, wider radial facets that are inclined rather than subvertical, in the larger anal plate
, different plating of the anal opening, and the broad rather than narrow axial canal of the stem facet.
Preopercular pores (prop) scarse, present in a midline on mid-dorsum anterior to anal plates
. Dorsal tubercles (dtub) present, totaling 10 to 12 around body margins.
convex, with numerous short and medium-size setae.
According to Frota-Pessoa (1954), the representative characteristics of the tripunctata group are: the mesonota are without markings, the carina are never sulcate and the anal plates
are separated from the genital arch.
Isofemale lines were sampled in four separate experiments corresponding to four sets of trait measurements: (1) posterior lobe area; (2) anal plate
area and tibia length; (3) sternite bristle number; and (4) bristle number for anal plates
, clasper, sex comb, and vaginal plate.
2G); supra anal plate
yellowish brown, with anterior margin slightly concave, lateral ones constricted on median portion and posterior rounded, with thick bristles (Fig.
and identified these structures as anal plates
. However, Deonier (1970) neither described the morphology of the anal plates
in detail, nor attempted to delineate a function.
Supra anal plate
triangular, with a weak medial depression basally, the tip rounded.