Telmatactis clavata (Stimpson, 1855)

Li, Yang, Liu, Rui-Yu, Liu, J. Y. & Xu, Kuidong, 2013, Phytocoetes sinensis n. sp. and Telmatactis clavata (Stimpson, 1855), two poorly known species of Metridioidea (Cnidaria: Anthozoa: Actiniaria) from Chinese waters, Zootaxa 3637 (2), pp. 113-122 : 118-121

Telmatactis clavata (Stimpson, 1855)

Figures 5–7

Edwardsia clavata Stimpson, 1855: 376 . (Non Pei, 1998: 73, fig. 77.) Telmatactis clavata: Carlgren, 1949: 90 . Uchida & Soyama, 2001: 43.

Material examined. All specimens were collected from the intertidal zone of the South China Sea and preserved in 70% ethanol. MBM184348 (2 specimens), collected from Yongxing Island (Woody Island; 16°49ʹN, 112°20ʹE) of Xisha Islands (Paracel Islands) by Mr. Fengshan Xu on 18 May 1958; MBM183937 (2 specimens), collected from Yongxing Island; MBM183965 (1 specimen), collected from Yongxing Island by Mrs. Zunan Pei on 31 May 1981; MBM183941 (1 specimen), collected from Zhaoshu Island (16°57ʹN, 112°15ʹE) of Xisha Islands on 7 April 1980; MBM183985 (1 specimen), collected from Guangjin Island (16°26ʹN, 111°42ʹE) of Xisha Islands by Mr. Zhican Tang on 22 May 1975; MBM183802 (1 specimen), collected from Weizhou Island (21°03ʹ N, 109°04ʹ E), Guangxi Province, China by Mr. Xiutong Ma on 15 April 1978.

Column. Column elongated, almost cylindrical, usually widest distally, gradually narrowing proximally in both expanded and contracted preserved specimens ( Figures 5 A, B). Column length 14–55 mm; diameter 3–10 mm at narrowest part, 10–25 mm at widest part; pedal disc diameter 5–12 mm. Column of live individuals dark yellow. Column divided into scapus and scapulus, the former creamy, large, with a rough, wrinkled cuticle; the latter whitish or opaque-white, narrow and naked ( Figures 5 A, B). Scapus without tenaculi or cinclides. Pedal disc adherent, more or less circular, commonly slightly wider than the most proximal column ( Figure 5 A).

Oral disc and Tentacles. Oral disc circular, furrowed, creamy in contracted specimens; translucent, mesenterial insertions visible as pale lines in expanded specimens ( Figure 5 ). Oral disc diameter exceeds column diameter, especially in expansion. Mouth concave, same color as oral disc in contracted specimens; round, creamy white, and elevated in center of disc in expanded specimens. Actinopharynx well developed, occupying about 1/3 length of column, same color as mouth in both contracted and expanded preserved specimens.

Tentacles capitate; short in contraction, of moderate length in expansion ( Figure 5 ). Inner tentacles larger than outer ones, typically erect; outer tentacles more or less horizontal in expanded specimens ( Figures 5 B, C). In regular adult specimens, 72 tentacles hexamerously arranged in five cycles: 6 + 6 + 12 + 12 + 36; the first four cycles corresponding to endocoels, and the outermost cycle corresponding to exocoels ( Figure 5 C). According to collectors’ notes, large tentacles of live individuals grayish, with dark brown or purple rings; small tentacles brownish, with white rings. In preserved specimens, tentacles typically darker than oral disc.

Internal Anatomy. Two elongate, symmetrical siphonoglyphs; each attached to pair of directive mesenteries. Up to 36 pairs of mesenteries hexamerously arranged in four cycles: 6 + 6 + 12 + 12 ( Figure 6 D); all extend full length of column. Mesenteries of first cycle fertile, perfect (including directives); those of second cycle imperfect, without musculature, sterile, but with filaments and acontia; those of third and fourth cycles imperfect, small, sterile, bearing no muscles, filaments, or acontia. Acontia delicate, not tightly coiled, arise from primary mesenteries proximally and from imperfect mesenteries at midcolumn. Dioecious. Azooxanthellate.

Marginal sphincter muscle mesogloeal, elongate ( Figures 6 A, B). Longitudinal muscles of tentacles and radial muscles of oral disc mesogloeal ( Figure 6 C). Longitudinal retractor muscles strong, circumscribed ( Figure 6 E). Parietobasilar muscles absent.

Cnidom. Spirocysts, basitrichs, microbasic amasitigophores, microbasic p -mastigophores ( Figure 7 ). See Table 2 for distribution and size.

Tissue Cnida type N n Range, in μm

Tentacle Basitrich (A) 2/2 134 26.0–74.0 × 2.0–3.0 Spirocyst (B) 2/2 89 15.0–60.0 × 2.0–3.0 Microbasic amastigophore (C) 2/2 4 31.0–36.0 × 4.0

Column Basitrich (D) 2/2 53 14.0–23.0 ×3.0

Actinopharynx Microbasic p -mastigophore (E) 2/2 4 25.0–27.0 × 5.0

Microbasic amastigophore (F) 2/2 32 40.0–72.0 × 7.0–10.0 Large basitrich (G) 2/2 33 25.0–33.0 × 3.0

Small basitrich (I) 2/2 16 13.0–17.0 (20.0) × 1.0–2.0

Filament Microbasic p -mastigophore (H) 2/2 35 (8.0) 12.0–15.0 × 3.0–4.0

Basitrich (I) 2/2 18 12.0–17.0 × 1.0–2.0

Acontia Basitrich (J) 2/2 98 17.0–25.0 × 2.0

Microbasic amastigophore (K) 2/2 44 50.0–66.0 × 9.5–13.0 Distribution and Habitat. Telmatactis clavata (Stimpson, 1855) was previously recorded from Ryukyu Islands (Stimpson, 1855; Uchida & Soyama, 2001). This is the first record in China, where it was collected from Xisha Islands and Guangxi coast of the South China Sea. All our specimens were found attached to crevices of rocks and in dead coral in shallow water.

Remarks. Telmatactis clavata was described as a member of family Edwardsiidae by Stimpson (1855), and transferred into the family Isophelliidae Stephenson, 1935 by Carlgren (1949) in recognition of the differences between this species and members of Edwardsiidae in terms of anatomy and mesentery arrangement. More recently, Rodríguez et al. (2012) questioned the significance of basilar muscles in higher level taxomomy of sea anemones and synonymized Isophelliidae with Andvakiidae Danielssen, 1890 based on molecular phylogenetic analysis.

The original description of Telmatactis clavata is very brief, except of details in its color. Stimpson (1855) could not distinguish the first four cycles of tentacles and mistook the tentacles as two equal series. Carlgren (1949) mentioned in the generic diagnosis of Telmatactis that the imperfect mesenteries may be atypically arranged. Our specimens showed that T. clavata has an atypical arrangement of mesenteries, with the highest cycle of mesenteries existing just in the exocoels between the secondary and tertiary mesenteries, but absent in the exocoels between the primary and tertiary mesenteries.

Pei (1998) reported Telmatactis clavata from the Bohai Sea and South China Sea with the note “body wall with dense cross striations, with eight longitudinal furrows dividing body into eight equal parts”. The description matches with the generic feature of Edwardsia de Quatrefages, 1842 instead of Telmatactis . As the description and drawing are incomplete and no specimens exist for examination, it is not possible to make a precise identification for the species indicated by Pei (1998).

So far, T. clavata has been recorded only from the southern waters of Japan where the warm current Kuroshio flows through and the tropical waters of China. It is likely a species inhabiting only warm waters in the western Pacific.

Figures

FIGURE 5. External morphology of Telmatactis clavata (Stimpson, 1855). Scale bars = 10 mm. A, C. Lateral (A) and oral (C) view of a contracted specimen, showing the arrangement of tentacles. B. Lateral view of an expanded specimen.

FIGURE 6. Internal anatomy of Telmatactis clavata (Stimpson, 1855). A. Longitudinal section through margin. T, tentacle. Arrow indicates marginal sphincter muscle. Scale bar = 0.5 mm. B. Cross section of marginal sphincter muscle. Scale bar = 0.2 mm. C. Cross section of tentacle. Scale bar = 0.2 mm. D. Diagram illustrating arrangement of mesenteries. D, directive mesentery pairs. Numbers indicate the cycles of mesenteries. E. Cross section of mesenteries through actinopharynx, showing retractor muscle (R). Arrow indicates siphonoglyph. Scale bar = 0.5 mm.

FIGURE 7. Cnidae from Telmatactis clavata (Stimpson, 1855). Scale bar = 20 μm (A – K in scale). Tentacle: A. Basitrich. B. Spirocyst. C. Microbasic amastigophore. Column: D. Basitrich. Actinopharynx: E. Microbasic p - mastigophore. F. Microbasic amastigophore. G. Large basitrich. Filament: H. Microbasic p - mastigophore. I. Small basitrich. Acontia: J. Basitrich. K. Microbasic amastigophore.