Molgula tzetlini Sanamyan 1993
Molgula tzetlini Sanamyan, 1993 (Figure 6) Molgula tzetlini Sanamyan, 1993: 129. Material examined: Four specimens collected during July and August 1995 on Medny Island (Commander Islands), 8–20 m, KBPIG 700 / 3, 723/5, 725/6, 741/7; Kamchatka, Avacha Bay, 5 m, one specimen, KBPIG 1066 /8. Previous...
| Main Authors: | , |
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| Format: | Other/Unknown Material |
| Language: | unknown |
| Published: |
2007
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| Subjects: | |
| Online Access: | https://zenodo.org/record/5098331 https://doi.org/10.5281/zenodo.5098331 |
| Summary: | Molgula tzetlini Sanamyan, 1993 (Figure 6) Molgula tzetlini Sanamyan, 1993: 129. Material examined: Four specimens collected during July and August 1995 on Medny Island (Commander Islands), 8–20 m, KBPIG 700 / 3, 723/5, 725/6, 741/7; Kamchatka, Avacha Bay, 5 m, one specimen, KBPIG 1066 /8. Previous records: NW Pacific, Commander Islands (Sanamyan, 1993). Description. All specimens are small, 5.5–11 mm in diameter and heavily incrusted with sand. Sand grains are attached directly to the test and hair-like processes are not present. The shape of the body removed from the test is characteristic (Fig. 6B). Both siphons are long and muscular and have well marked pointed lobules fringing the rim of the apertures. Body muscles are present only on the anterior half of the body and consist of 1) crowded thick circular siphonal muscles present only on the siphons and not extending outside the bases of the siphons; 2) spaced thick muscle bands radiating from siphons to about the middle of the body; 3) compact field of short muscle fibers crossing the intersiphonal area and completely covering the region of neural ganglion and dorsal tubercle; 4) rows of short transverse muscles running along mid-ventral and middorsal lines in the anterior half of the body. The branchial sac has a regular structure of seven longitudinal rows of 12 (in the most ventral row) or six (in all other rows) square spirals separated by five transverse vessels. There are seven branchial folds, all except the most ventral one being well developed with 4–6 internal longitudinal vessels. The most ventral fold is represented by only one longitudinal vessel in all the specimens. The typical formula is: (1)(5)(5)(6)(6)(6)(6)DL(5)(6)(5)(6)(4)(4)(1). Longitudinal vessels are not present between the folds or, rarely, a single vessel is between the dorsal lamina and adjacent fold on the right side of the branchial sac. Radial and rather irregular parastigmatic vessels are present and bear minute papillae (recognizable only after staining). The dorsal lamina ... |
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