Edwardsia mcmurrichi, Daly, Marymegan & Ljubenkov, John C., 2008

Daly, Marymegan & Ljubenkov, John C., 2008, Edwardsiid sea anemones of California (Cnidaria: Actiniaria: Edwardsiidae), with descriptions of eight new species, Zootaxa 1860, pp. 1-27 : 10-11

Edwardsia mcmurrichi sp. nov.

Figs. 1 , 6 ; Table 2

123°32.99'W, 16­Oct­2000, 2650 m; CAS 175243, San Francisco, California, SF­DODS Sta. 64, 37°36.01'N 123°33.01'W, 25­Sep­2002, 3136 m; CAS 175236, San Francisco, California, SF­DODS Sta. 64, 37°35.98'N 123°32.96'W, 26­Sep­2003, 3130 m; CAS 175249, San Francisco, California, SF­DODS Sta. 116, 37°35.00'N 123°29.00'W, Fall 2004, 3000 m.

External anatomy. Tentacles filiform, 16. Scapus with prominent nemathybomes forming distinct longitudinal rows distally, scattered proximally ( Fig. 6 A). Periderm thin, fluffy, of fine sediment. Mesenterial insertions visible as furrows with nemathybome rows forming ridges between them distally ( Fig. 6 A). Physa naked, may be retracted inside scapus ( Figs. 6 A, C).

Internal anatomy and histology. Parietal and retractor muscles restricted, relatively weak ( Figs. 6 B, D). Retractor muscle with pennon; branches of pennon relatively short ( Fig. 6 B). Parietal muscle ovoid to trianguloid; branches closer to body wall ramified and longer, central lamella thicker than lateral branches ( Fig. 6 D). Gonochoric: all examined specimens either male or female. Nemathybomes large, single, sunken into mesoglea, with top edge protruding into epidermis ( Fig. 6 E). Epidermis and mesoglea of scapus irregular, forming troughs and valleys ( Figs. 6 C, E). Mesoglea of scapus thicker than that of physa; epidermis thicker and more glandular on physa than on scapus ( Fig. 6 C).

Cnidom. Spirocysts, basitrichs, microbasic p ­mastigophores ( Figs 6 F–M; see Table 2 for size and distribution).

Etymology. Named for J. Playfair McMurrich (1859–1939), our predecessor in the study of southern California Edwardsiidae . Dr. McMurrich described 65 species of Hexacorallia (including E. californica ) and was president of both the American Association for the Advancement of Science and the Royal Society of Canada.

Distribution and habitat. Known only from the basin floor of the Farallons Escarpment, at depths of 2100–3100 m, co­occurring with P. h e i a. This region blends into the greater Pacific Basin, thus E. mcmurrichi and P. h e i a may occur more widely in the Pacific abyssal plain.

Similar species. This species resembles E. californica in general size and external anatomy. Despite their similar body size, the retractor muscles of E. mcmurrichi are much smaller than those of E. californica . The two differ in cnidom: E. mcmurrichi has a single, smaller size of nemathybome nematocyst. Additionally, E. mcmurrichi occurs in deep basins of central California, whereas E. californica occurs at intertidal and shallow shelf depths in southern California.

Remarks. None.

Figures

FIGURE 1. Comparative external anatomy of Edwardsiidae from southern and central California. Scale bar = 5 mm. A. Edwardsia californica (McMurrich, 1913). B. Edwardsia handi sp. nov. C. Edwardsia juliae sp. nov. D. Edwardsia mcmurrichi sp. nov. E. Edwardsia olguini sp. nov. F. Edwardsia profunda sp. nov. G. Paraedwardsia heia sp. nov. H. Scolanthus scamiti sp. nov. I. Scolanthus triangulus sp. nov.

FIGURE 6. Edwardsia mcmurrichi sp. nov. A. External anatomy, holotype CAS 175239. Scale bar = 3 mm. B. Cross section of retractor muscle, CAS 175328. Scale bar = 300 μm. C. Longitudinal section through aboral end, CAS 175328. Black arrow demarcates physa; note region of physal epidermis missing. D. Cross section of parietal muscle, CAS 175328. Scale bar = 100 μm. E. Cross section of scapus showing nemathybome, CAS 175328. Note relatively thick mesoglea and relatively thin epidermis. Scale bar = 200 m. F – M, Cnidae. Scale bar below I and J = 20 μm, applies to all capsules. F. Large spirocyst. G. Large basitrich of tentacle. H. Large basitrich of actinopharynx. I. Small basitrich of actinopharynx. Cnidae of similar size and morphology are found in filaments. J. Microbasic p ­ mastigophore of filament. Cnidae of similar size and morphology are found in actinopharynx. K. Large basitrich of filament. L. Basitrich (or pterotrich?) of nemathybome. M. Small spirocyst.