Paranesidea sterreri Maddocks, 1986
Paranesidea sterreri: female right and left valve exteriors
Taxonomic Characterization: Paranesidea sterreri appears translucent white in alcohol with an elaborate opaque-white patch pattern. However, the fresh carapaces have dark brown lining the interior except for a small, irregular clear spot in the anterodorsal region and sometimes a smaller clear spot posteromedially. The carapace exterior is densely pitted with small, round punctae. The species has long brown external setae. The male left valve has rounded contours in lateral view, and the ventral margin is gently rounded without angles. The left valve is angulate, upright, with anteroventral and posteroventral striate marginal frills. The hemipenis has slender basal and middle lobes, and a small, elongate-oblong distal lobe, without heavily chitinized protuberances, swellings or setae. The copulatory tube is short and somewhat arched. In comparison to the male, the female is larger and proportionately much higher (Maddocks & Iliffe, 1986).
Disposition of Specimens: All specimens were deposited in the United States Museum of Natural History: male holotype (USNM 216432), paratypes (USNM 216433-216435).
Ecological Classification: Possibly stygophilic or accidental.
Size: Length of right valve of adult female 0.78 mm, adult male 0.79 mm.
Number of Species in Genus: At least 6.
Species Range: Known from Deep Blue Pool, Harrington Sound, Grenadier Pool, Castle Harbor, Ferry Reach, North Lagoon, and South Shore reefs in Bermuda (Maddocks & Iliffe, 1986).
Closest Related Species: Paranesidea sterreri is most similar to three species described from the Bahamas and Florida: P. harpago, P. gigacantha and P. arostrata. However, these three species have different shapes, opaque patterns, and differently structured hemipenes. Also, P. gigacantha has a smooth exterior (Maddocks & Iliffe, 1986).
Habitat: Anchialine limestone caves and open water environments
Ecology: P. sterreri specimens were collected in sediment and algal samples. Bairdiacea are sediment-eating epibenthos. Unable to swim, they climb freely over all benthic surfaces. The noticeable high diversity of Bairdiacea characterizes coralline faunas and those of other habitats with coarse-grained sediments and abundant sessile invertebrates. The presence of this species in Deep Blue and Grenadier cave pools shows open connection to the outside.
Life History: Collected specimens included 21 specimens and 187 subfossil specimens.
Evolutionary Origins: P. sterreri is very common in open water environments and is one of the most common species of Bairdiacea on Bermuda. Their presence in caves shows open connection to the outside (Maddocks & Iliffe, 1986).
Contributor: Dr. Rosalie F. Maddocks, University of Houston, Houston, Texas USA
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