Edwardsia alternobomen, Izumi & Fujita, 2019

Izumi, Takato & Fujita, Toshihiko, 2019, Two species of Edwardsia having gigantic nematocysts, E. aff. tuberculata and E. alternobomen sp. nov. (Cnidaria; Anthozoa; Actiniaria; Edwardsiidae) from Japan, Zootaxa 4661 (3), pp. 533-544 : 538-542

publication ID	https://doi.org/ 10.11646/zootaxa.4661.3.7
publication LSID	lsid:zoobank.org:pub:7A7E6A85-B904-4BC2-90A1-8CA19CA86F24
persistent identifier	https://treatment.plazi.org/id/03FD87A5-FFCC-EF65-99D1-FB90FEA160F0
treatment provided by	Plazi
scientific name	Edwardsia alternobomen
status	sp. nov.

Treatment

Edwardsia alternobomen sp. nov.

New Japanese name: gyorai-mushimodoki-ginchaku

Figs. 3 View FIGURE 3 , 4 View FIGURE 4 ; Table 1 View TABLE 1

urn:lsid:zoobank.org:act:74DA6AE3-8828-4B63-ADE6-A29C8BDCC8F0

Material examined. The holotype: NSMT-Co 1657, dissected specimen, histological sections (7 slides), and prepared cnidae (5 slides), October 13th, Hokabira-coast , Hinoshima Island , Amakusa Islands, Kumamoto Prefecture (32°23′39″N, 130°25′21″E; Fig. 1B View FIGURE 1 ), 1 m depth, collected by Takato Izumi; 3 paratypes: NSMT-Co 1656, histologi- cal sections (3 slides), and prepared cnidae (5 slides), June 24th, 2014, same locality as holotype, collected by Naoto Jimi; NSMT-Co 1658, 1659, dissected specimen, same date, locality and collecter as NSMT-Co 1657 GoogleMaps .

External anatomy. Column cylinder-like, both in living and preserved specimens, wrinkled by huge nemathybomes, 25–30 mm in whole length (30 mm in NSMT-Co 1657 [holotype]), and 2–4 mm in width (3 mm in NSMT-Co 1657) in expanded specimens, ( Fig. 3A View FIGURE 3 ). Body divided into capitulum, scapus and physa ( Fig. 3A View FIGURE 3 ). Scapus covered with bright orange periderm. Nemathybomes of two types: huge, up to 1.5 mm in diameter, protruding like papillae, and small, less than 300 µm in diameter, covered by periderm. Nemathybomes queued in eight-rows: four rows of larger ones and four rows of smaller ones arranged alternately: all larger nemathybomes in four rows, and never in the other four rows ( Fig. 3B View FIGURE 3 ). Compared to E. tuberculata , large nemathybomes sparse in each row. Aboral physa differentiated from scapus, naked, a little rounded, without nemathybomes ( Fig. 3A View FIGURE 3 ). Tentacles transparent with a row of white patches and two rows of winered tiny patches on surface, 2-4 mm in length, 12 in number, in two cycles of six tentacles each ( Fig. 3C View FIGURE 3 ). Oral disk 1 mm in diameter, light in color, with wine red circle, and pale white rhomb only on dorsal side ( Fig. 3C View FIGURE 3 ).

Internal anatomy. Eight perfect mesenteries, macrocnemes, distributed along whole body from distal to proximal end. Paired dorsal and ventral directives plus four lateral, unpaired mesenteries ( Figs. 3F, H View FIGURE 3 ). Four tiny microcnemes, one of the fewest in Edwardsiidae , each without muscles, limited only to distal-most column. Two microcnemes between dorso- and ventro-lateral mesenteries and two between ventro-lateral mesenteries and ventral directives. One tentacle in each end- or exo- coel. All macrocnemic mesenteries bear retractor and parietal muscles. Retractor muscle of each lateral mesentery faces ventrally ( Fig. 3F View FIGURE 3 ). Each retractor muscle distinctly developed as pennon, restricted to filament side; with 15–20 multiply branched muscular processes next to actinopharynx, and with 10–15 multiply branched muscular processes in lower part ( Fig. 3H View FIGURE 3 ). Parietal muscles of macrocnemes comparatively distinct, semi-elliptic or triangular shape with 3–4 slightly branched muscular processes in each side ( Fig. 3E View FIGURE 3 ). Actinopharynx very short, grooved, with no distinct siphonoglyph. Tentacular longitudal muscle ectodermal but indistinct. Marginal sphincter muscle and basilar muscle absent ( Fig. 3D View FIGURE 3 ). Mesoglea generally thin in mesenteries, and comparatively thick in body wall (Fig, 3F, H). Larger nemathybomes, however, far thicker than mesoglea, greatly protruding from the body wall and containing very large basitrichs ( Fig. 3F, I View FIGURE 3 ). Dioecious: gonads between retractor muscle and filaments; oocytes in gonads of NSMT-Co 1656.

Cnidome. Spirocysts, basitrichs, and microbasic p -mastigophores ( Table 1 View TABLE 1 , Fig. 4 View FIGURE 4 E–H; NSMT-Co 1656 [paratype]). Two sizes of basitrichs in actinopharynx; three sizes of basitrichs in nemathybomes.

Etymology: the specific epithet consists of alterno (alternately in Latin) and bomen (meaning nemathybome). This name is derived from the alternately arranged nemathybomes.

Deriviation of Japanese name. “Gyorai” in Japanese means torpedoes. This name derives from the elongated shape of large nemathybomes, which contain nemathybomes densely arrayed like torpedoes in a hanger.

Remarks. This species has two characteristic features: 12 tentacles and huge basitrichs reaching 200 µm in length. There are a few Edwardsia species that have only 12 tentacles: E. andresi Danielessen, 1890 , E. duodecemtentaculala Car 1gren, 1931, E. fusca Danielessen, 1890 , E. jonesii Seshaiya and Cuttress, 1969 , and E. juliae Daly and Ljubenkov, 2008 . Edwardsia alternobomen can be distinguished from the former three species by the arrangement of nemathybomes: it has rows of nemathybomes whereas the nemathybomes of E. andresi , E. duodecemlentaculata and E. fusca are scattered (see England. 1987). Concerning the other two species, E. alternobomen can be distinguished from E. jonesii in having extremely large nemathybomes and no nemathybomes in two rows: nemathybomes of E. jonesii are very small and sometimes become double rows in mid scapus ( Seshaiya and Cuttress, 1969), and can be distinguished from E. juliae in having two cycle of slender tentacles, whereas the tentacles of E. juliae are blunt and in a single cycle ( Daly and Ljubenkov, 2008). In addition, E. alternobomen can be distinguished from all species mentioned above by its huge basitrichs, which reach 200 µm in length. The maximum length of basitrichs in the nemathybomes of E. alternobomen is the longest reported for Edwardsiidae .

This new species have many basitrichs> 150 µm in length. Such large basitrichs are also observed in four other species of Edwardsia , E. tuberculata , E. californica , E. claparedi , and E. maroccana (see Remarks of E. tuberculata , above). However, E. alternobomen sp. nov. can be distinguished easily by having only 12 tentacles, while the other Edwardsia species here with very large basitrichs all have 16 tentacles. Because E. alternobomen sp. nov. is sexually mature, we do not think that it is a juvenile. Beyond the differences in size and arrangement of nemathybomes, Edwardsia tuberculata has larger and far more densely arranged nemathybomes than E. alternobomen sp. nov. Moreover, in E. tuberculata the physa is flattened whereas in E. alternobomen it is rounded. The muscular processes of E. tuberculata are about as twice as numerous as those of E. alternobomen ( Carlgren, 1921) . In Ed- wardsia californica , the mesenterial muscle has a distinctive shape ( Carlgren, 1936) and far more processes than the muscles of E. alternobomen . The body of Edwardsia claparedi is approximately four times longer and broader than E. alternobomen ( Manuel 1981) . Edwardsia maroccana has far more developed retractor muscles (with 30 processes: Carlgren, 1931) than does E. alternobomen . In addition, E. alternobomen sp. nov. has two sizes of nemathybomes alternatively arranged in eight rows ( Fig. 3B View FIGURE 3 ), whereas any other previously described Edwardsia species does not. This unusual arrangement of nemathybomes is one of the most prominent morphological feature for this new species.