Sarsiella murrayana Scott 1894

Sarsiella murrayana Scott, 1894

Sarsiella Murrayana Scott, 1894:140, pl. 14: fig. 58; pl. 15: figs. 24, 28, 29. 31.

Sarsiella murrayana.—Müller, 1912:37 [key, diagnosis].

MATERIAL.—Through the courtesy of Dr. Roger Lincoln, I received from the British Museum (Natural History) the two specimens in alcohol described by T. Scott (1894) from Lagoon, Sao Tome Island. Only the attached valves of the larger specimen of the two were in the vial. The smaller specimen was complete and undissected, except both 2nd antennae seem to be missing. The vial contained a label with the words “Sarsiella murrayana”, Buccaneer, W. coast of Africa.”

In his description Scott (1894:140) does not mention ribs on the carapace, nor does his illustration (pl. 14: fig. 58) show them. In a key, Muller (1912:37) used the absence of ribs on S. murrayana to separate that species from S. tumida A. Scott, 1905. Therefore, I was surprised to find on the type-specimens both an upper and lower horizontal rib. The carapace of the larger of the two specimens is reillustrated herein. Some of the appendages of the smaller specimen were partly visible through the shell, or were extending from it, so I was able to illustrate them, but details are lacking. Also, because the valves on the smaller specimen were slightly agape, I was able to draw the main features of inner side of the caudal process of both valves.

Scott (1894:140) stated that he was describing a male. It is obvious, however—because of the lack of brushlike filaments on the 5th joint of the 1st antenna that he illustrated (pl. 15: fig. 24)—that the specimen is not an adult male. The shape of the carapace suggests that the specimen is a juvenile, but study of additional specimens are necessary in order to be certain of that and to establish the sex.

SUPPLEMENTARY DESCRIPTION.—Surface of carapace punctate with upper and lower horizontal rib tending to meet at posterodorsal corner of each valve (Figure 27); anteroventral surface of each valve outside ribs with 3 very faint, low radial riblets (these visible only with valve tilted); punctae (Figure 28c) filled with debris so that spines, if present, not visible; no spines observed between punctae; long bristles with broad base extremely sparse on valve surface except along margins.

Infold: Caudal process of each valve of smaller specimen with 3 bristles (Figure 28a,b).

Size: Larger specimen: length excluding caudal process, 0.82 mm; length including caudal process, 1.08 mm; height, 0.66 mm. Smaller specimen: length, 0.56 mm; height, about 0.38 mm. Scott (1894) gave the length as 0.93 mm; presumably, this was of the larger specimen.

First Antenna (Figure 28d): The b-bristle of 7th joint only slightly longer than a-bristle; remaining bristles of 7th and 8th joints about same length as sensory bristle of 5th joint; no filaments observed on bristles.

Second Antenna: Missing on specimen. Endopodite unknown.

Mandible: Visible parts typical for genus (Figure 28e).

Maxilla: Partly visible, typical of genus (Figure 28f).

Seventh Limb: Not visible on specimen.

Furca (Figure 28g,h): Each lamella with 5 claws followed by few minute spines; claw 1 joined to lamella without suture, claws 2–5 separated from lamella by sutures; claws 1–3 with teeth forming single row along posterior margins; large teeth alternate with several smaller teeth.

Lateral Eye: Each eye with 3 ommatidia (Figure 28i).

Medial Eye and Rod-shaped Organ: Medial eye larger than lateral eye, pigmented (Figure 28i). Rod-shaped organ elongate with rounded tip; suture not seen with certainty (Figure 28i).

This family contains three genera: Rutiderma Brady and Norman, 1896, Alternochelata Kornicker, 1958, and Scleraner Kornicker, 1975. Only Rutiderma is represented in the collection.

This genus is represented in the collection only by Rutiderma leloeuffi, new species. It is widespread between latitudes 45°N and 52°56′S and in depths of 1–196 m.