Diadumene leucolena (Verrill, 1866)

Raghunathan, C. & Choudhury, Smitanjali, 2017, New distributional records of Actiniarian sea anemones from Andaman and Nicobar Islands, Records of the Zoological Survey of India 117 (1), pp. 26-26 : 26-

Diadumene leucolena (Verrill, 1866) , Figure 4

Synonyms

Sagartia leucolena Verrill, 1866 (Original description) Cylista leuconela (Verrill, 1866)

Sagartia (Thoe) leucolena Verrill, 1866

Diadumene kameruniensis (Carlgren, 1927)

Material Examined: Five specimens were collected from the intertidal regions of Chouldari (Lat. 11°37.224’N; Long. 92°40.285’E), South Andaman on 9.I.2015. Registration No. ZSI/ ANRC -13005.

Description: The pedal disc is well developed with 5.94 mm in diameter ( Figure 4a ). Column is 15 mm length which is divisible into scapus and capitulum ( Figure 4b & d ). The column appears smooth from a distance, but is studded with small dark bumps when looked at closely. The double stripes are prominently seen on the column ( Figure 4a & c ). Mouth is present with prominent lips ( Figure 4e ). The capitulum is smooth. The scapus is with cinclides ( Figure 4f ). The tentacles are about 66 number, hexamerously arranged in four cycles (12+12+18+24 = 66) ( Figure 4a ). The tentacles are long, tapered, numerous, more regularly arranged, which are not retractile ( Figure 4a ). All of the inner tentacles are typically thicker than the outer tentacles ( Figure 4a ). Acontia is well developed.The retractor muscles are observed ( Figure 6a ). Gametogenic tissues are well observed ( Figure 6a &b ). Parietobasilar and basilar muscles are weak ( Figure 6c ).

The columns of the individuals observed in the field were slightly pinkish or salmon or orange in colour ( Figure 4a ) and transparent with a tinge of green near the upper part of the column. The mesenteries were visible as 24 white double stripes on the column. The colour of tentacles are off white ( Figure 4a ).

Cnidocysts

Cnidocyts contain spirocysts and nematocysts such as micro basic p-mastigophores, basitrichs and micro basic amastigophores were derived from various organs of D. leucolena ( Table 2) and all are illustrated in Figure 5 .

Habitat: It is common to abundant along the bay margin, estuaries and sheltered waters, in fouling communities where it grows on oysters, rocks, seaweeds, pilings, and floats. It can also occur in sheltered tide pools, and is especially tolerant of variable salinities (Carlton 1979; Cohen and Carlton 1995).

The specimen reported here was found in mud flat area of shallow water occurring at depth of 1m.

Distribution: This Atlantic anemone, occurring from at least Cape Cod to South Carolina, was first reported from the Oakland estuary by Sander (1936), although it may have been present in the Bay since the 19 th century (Cohen and Carlton, 1995). Hand (1956) described it in detail from the Bay of central California. It was recorded from Atlantic coast oyster beds (Wells, 1961) as ship fouling or in ballast water. It has also been reported from southern California bays and from Coos Bay, Oregon (Carlton, 1979; Cohen and Carlton, 1995).

India: Chouldari, South Andaman.

Remark: New record to Indian waters

Figures

Figure 4. Diadumene leucolena [a. Diadumene leucolena in live condition; b. Capitulum and scapus in live condition; c; Specimen in preserved condition; d. Capitulum and scapus in preserved condition; e. Mouth; f. Cinclides].

Figure 5. Cnidocysts of Diadumene leucolena [a. Spirocyst (G) from tentacle; b. Large basitrich from tentacle; c. Microbasic amastigophores from tentacles; d. Small basitrich from Mesenterial filaments; e. Large basitrich from Mesentrial filaments; f. Microbasic p- mastigophore from Mesentrial filaments; g. Spirocyst (G) from Mesentrial filaments; h. Basitrich from Actinopharynx; i. Spirocysts (G) from Actinopharynx; j. Microbasic amastigophores from Actinopharynx; k. Basitrich from Acontia; l. Microbasic p- mastigophore from Acontia].

Figure 6. Cross section of Diadumene leucolena [a. Middle portion of column showing mesenteries; b. Non-muscular gametogenic region of fertile mesenteries; c. Weak basilar muscles].