Actinostella flosculifera ( Le Sueur, 1817 )

Gonzalez-Muñoz, Ricardo, Simões, Nuno, Sanchez-Rodriguez, Judith, Rodriguez, Estefania & Segura-Puertas, Lourdes, 2012, First Inventory of Sea Anemones (Cnidaria: Actiniaria) of the Mexican Caribbean, Zootaxa 3556, pp. 1-38 : 11-16

Actinostella flosculifera ( Le Sueur, 1817)

( Figure 3 , Table 2 )

Actinia flosculifera Le Sueur, 1817: 174 .

Metridium praetextum Couthouy in Dana, 1846: 150 –152.

Actinostella formosa Duchassaing, 1850: 10 .

Oulactis flosculifera Milne-Edwards, 1857: 292 .

Oulactis conquilega Duchassaing & Michelotti, 1860 , pl. VII, fig. 7.

Oulactis Flosculifera [sic] Duchassaing, 1870: 20.

Evactis flosculifera Andres, 1883: 244 .

Oulactis foliosa Andres, 1883: 297 .

Oulactis fasciculata McMurrich, 1889b: 108 –110.

Asteractis n. sp.: Duerden, 1897: 455.

Asteractis expansa Duerden in McMurrich, 1898: 232 –234.

Cradactis fasciculata Haddon, 1898: 436 .

Asteractis flosculifera Verrill, 1899a: 45 –46.

Actinactis flosculifera Verrill, 1900: 572 .

Actinostella flosculifera McMurrich, 1905: 7 .

Actinostella conchilega McMurrich, 1905: 4 –8.

Phyllactis flosculifera Stephenson, 1922: 283 .

Material examined.— Puerto Morelos (20°54’26.38” N, 86°50’43.14” W; 5 specimens); Isla Contoy (21°29’0.10” N, 86°47’39.10” W; 5 specimens); Akumal (20°23’37.03” N, 87°18’44.51” W; 1 specimen).

Diagnosis.—Fully expanded tentacles and marginal ruff to 120 mm in diameter. Oral disc 15–45 mm in diameter, with white spots ( Figure 3 B). Tentacles about 48, hexamerously arranged in four cycles, smooth, conical, tapering distally, moderately long, inner ones longer than outer ones, contractile, white, semi-transparent with scattered small circular white spots ( Figure 3 B). Column more or less elongated, 20–65 mm in height and 15–30 mm in diameter, smooth but with small rows of verrucae distally ( Figure 3 C, F). Above verrucae lies a marginal ruff (or collar) formed by 48 rows of small frond-like fused papillae, light brown or olive-green ( Figure 3 A, B). Pedal disc well developed, 11–29 mm in diameter ( Figure 3 D). Pedal disc and column beige, semi-transparent. Mesenteries hexamerously arranged in three cycles (24 pairs in specimens examined): first cycle (including directives) and some pairs of second cycle perfect and fertile, others imperfect and sterile; gonochoric (?), only oocytes in examined specimens ( Figure 3 E); same number of mesenteries distally and proximally. Two pairs of directives each attached to a well developed siphonoglyph. Retractor muscles strong and restricted; parietobasilar muscles well developed with a free mesogleal pennon ( Figure 3 E). Basilar muscles well developed. Marginal sphincter muscle not developed ( Figure 3 F). Zooxanthellae present. Cnidom: basitrichs, microbasic pmastigophores and spirocysts ( Figure 3 G–N; see Table 2 ).

Natural history.— Actinostella flosculifera inhabits fields of the seagrasses Thalassia testudinum and Syringodium filiforme , often between 0.5–5 m depth, in areas of the lagoon-reef zone with low wave energy. It is usually found with the column burrowed, but the pedal disc is actually adhered to buried rocks, shells or rhizomes of seagrasses. During the day, the tentacles remain contracted and the marginal ruff fully expanded, allowing zooxanthellae (particularly abundant in this area) to capture sunlight; during night the situation is the opposite, allowing tentacles to capture food ( Häussermann 2003). The marginal ruff is similar in color to dead leaves of seagrass, probably camouflaging this species.

Distribution.—From Bermuda to Brazil, along the entire Caribbean Sea (see Table 1). Also reported in Canary Islands (Ocaña & den Hartog 2002) and the Gulf of Guinea ( Wirtz 2003). This species is reported for the Mexican Caribbean in Punta Cancún, Punta Nizuc, and Isla Mujeres reefs (INE 1998a), but this is the first time recorded for Puerto Morelos, Akumal, and Isla Contoy reefs.

Remarks.—Three of the 10 valid species of Actinostella have been recorded in the Caribbean Sea: A. flosculifera , A. radiata ( Duchassaing & Michelotti, 1860) , and A. variabilis ( Hargitt, 1911) ( Fautin 2011) . According to McMurrich (1905), A. radiata resembles A. conchilega (= A. flosculifera ) in its general appearance but differs perhaps in the number of tubercles on the fronds and the verrucae in each longitudinal row, and in the circumscribed endodermal sphincter; however, the distinction between A. radiata and A. flosculifera remains unclear and needs further revision. The specimens of A. variabilis (= Cradactis variabilis ) showen in Hargitt’s (1911) description are actually specimens of Lebrunia coralligens ( Wilson, 1890) and perhaps some young individuals of L. danae . The diagnosis of Actinostella mentions a strong to very weak circumscribed marginal sphincter muscle ( Carlgren 1949; Häussermann 2003); however, like McMurrich (1905), we did not observe a distinct marginal sphincter muscle in the specimens examined. Further revision is needed to clarify the presence or absence of marginal sphincter in A. flosculifera .

Figures

FIGURE 3. — Actinostella flosculifera. (A) Live specimen in natural habitat. (B) Oral view. (C) Lateral view. (D) Pedal disc view. (E) Cross section through distal column. (F) Detail of longitudinal section of column margin. (G – N) Cnidae. — tentacles: (G) basitrich, (H) spirocyst; actinopharynx: (I) basitrich, (J) basitrich, (K) microbasic p - mastigophore; column: (L) basitrich; filament: (M) basitrich, (N) microbasic p - mastigophore. Abbreviations. — c: column, e: epidermis, g: gastrodermis, mru: marginal ruff, od: oral disc, o: oocyte, pb: parietobasilar muscle, pd: pedal disc, rm: retractor muscle, t: tentacles, vr: verrucae. Scale bars. — A – D: 10 mm; E – F: 200 µm; G – N: 25 µm.

Tables

TABLE 2. — Size and distribution of cnidae from preserved specimens examined. “ ml ” and “ mw ” are the means (length and width respectively), “ dl ” and “ dw ” are the standard deviations (length and width respectively), all in µm. “ # 1 ” and “ # 2 ” is the number of capsules measured per each specimen examined, “ p ” is the proportion of animals examined with respective type of cnida present.

Species Tissue Cnida	Capsule length (µm)	ml dl	Capsulewidth(µm)	m w	dw	# 1	# 2	p
Tentacle Microbasic p -amastigophore Microbasic p -amastigophore Spirocyst Actinopharynx Basitrich Bunodeopsis antilliensis Microbasic p -amastigophore Column Basitrich Microbasic p -amastigophore Microbasic p -amastigophore Filament Microbasic p -amastigophore	7.61–21.8 20.66–40 11–30 8–18.66 16.56–36 6–12.24 13–37.95 26–45.93 22.21–37	15.37 2.98 31.35 3.61 21.22 4.01 11.73 2.88 22.64 4.72 9.95 1.30 23.20 5.07 38.13 3.73 28.10 3.21	1.92–4.11 3.29–8.01 2.27–7 1.67–3 2.57–6 2–3 2.37–5.87 5.32–9 3.29–5	2.78 4.84 4.19 2.46 3.96 2.05 3.28 7.44 4.41	0.38 1.23 1.12 0.47 1.15 0.21 0.52 0.98 0.48	50 62 50 23 29 50 25 50 20	23 70 63 22 20 20 56 20 26	2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2
Tentacle Basitrich	16.99–26.18	21.73 2.37	1.74–3	2.24	0.36	50	36	2/2
Spirocyst	11–30.28	19.76 4.08	2–4	2.76	0.43	50	26	2/2
Actinopharynx Basitrich	8–15.07	10.72 1.54	1.55–2.25	1.96	0.12	50	25	2/2
Basitrich Actinostella flosculifera Microbasic p -mastigophore	20.46–28.62 17–31.27	24.30 1.82 21.84 3.35	2.14–4 3–8.41	3.24 5.37	0.60 0.83	50 36	27 24	2/2 2/2
Column Basitrich	12.71–18	15.6 1.11	1.79–3.21	2.10	0.26	50	30	2/2
Filament Basitrich	11.81–39.59	32.05 6.48	1.61–4.15	2.86	0.68	50	33	2/2
Microbasic p -mastigophore	12–28.86	20.40 4.28	3.55–7	5.31	0.83	50	25	2/2
Tentacle Basitrich Spirocyst Actinopharynx Basitrich	21–34.36 12–39.13 11–21.64	27.24 2.56 26.99 5.92 13.77 2.08	2.22–3.11 2–7 1–2.86	2.86 3.76 2.03	0.28 1.29 0.36	50 30 50	29 23 24	2/2 2/2 2/2
Basitrich Microbasic p -mastigophore Bunodosoma granuliferum Column Basitrich Basitrich Acrorhagi Basitrich Holotrich Filament Basitrich Microbasic p -mastigophore	17–32.39 14.33–24.15 13–19.22 17.25–30.34 13–26.88 26–46.04 15.14–38 18.11–36.06	26.86 2.91 21 1.98 16.69 1.22 25.91 2.11 16.86 2.63 37.86 3.53 26.97 6.76 22.73 2.82	2–3.66 3.93–6 1.75–3 2.25–4 1.5–3 2.84–5.18 1.92–8 4.21–7.36	3.03 4.80 2.19 3.23 2.15 3.48 4.59 5.18	0.29 0.47 0.38 0.42 0.36 0.40 2.07 0.66	50 17 50 50 55 18 24 10	22 31 22 22 20 20 24 33	2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2
Tentacle Basitrich	18.54–42	32.48 6.42	3.05–5	4.05	0.59	50	19	2/2
Spirocyst	17–42	29.28 6.98	3–5	3.58	0.55	50	20	2/2
Actinopharynx Basitrich	12.41–18.69	15.28 1.46	2–3.32	2.38	0.37	20	20	2/2
Basitrich	18.24–26	23.59 1.54	2.72–4	3.10	0.25	20	20	2/2
Condylactis gigantea Column Basitrich	14.15–21	17.7 1.92	1.67–3	2.07	0.30	50	20	2/2
Basitrich	14.39–38	25.57 4.19	1.84–5	3.31	0.67	50	20	2/2
Filament Basitrich	14.03–24.59	19.48 2.82	2–4	3.16	0.52	50	26	2/2
Basitrich	12.88–39	25.72 7.94	1.82–5	3.37	0.95	50	20	2/2
Microbasic p -mastigophore	19.59–27.13	24.46 1.87	3.16–5.07	4.23	0.48	20	10	2/2

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TABLE 2. (Continued)

Species	Tissue Tentacle	Cnida Microbasic p -amastigophore	Capsule length (µm) 32–99	ml 63.49	dl 17.08	Capsulewidth(µm) 6–10	m w 7.26	dw 0.87	# 1 20 # 2 20 p 2/2	# 2 20	p 2/2
		Spirocyst	26–51.03	37.99	5.26	4–5.94	4.95	0.55	20	20	2/2
	Actinopharynx	Microbasic p -amastigophore	19–46	38.41	5.02	4.36–7	5.55	0.69	20	20	2/2
Lebrunia danae	Column	Basitrico Microbasic p -amastigophore	7.05–13.09 13–24	9.36 18.61	1.79 1.98	1.81–3.47 3.65–7	2.26 4.37	0.51 0.61	0 20 21 20 1/2 2/2	21 20	1/2 2/2
	Filament	Microbasic p -amastigophore	30–81.02	47.19	8.1	5–8	6.37	0.7	20	21	2/2
	Pseudotentacles	Basitrich	11.29–17.3	13.77	1.68	2–4	2.87	0.53	7	4	2/2
		Microbasic p -amastigophore Macrobasic p -amastigophore	13.56–29.65 53–69.25	20.10 65.52	3.33 3.93	3.16–6 13.89–18.06	4.34 16.49	0.61 1.17	20 20 20 20 2/2 2/2	20 20	2/2 2/2
	Tentacle	Basitrich	11–21.04	16.48	1.90	2–3	2.7	0.4	50	20	2/2
		Spirocyst	13.94–24.34	18.89	2.72	2.37–3.57	2.94	0.27	4	20	2/2
	Actinopharynx	Basitrich	11–24	21.18	1.93	2–4.29	2.98	0.25	50	20	2/2
Phymanthus crucifer		Microbasic p -mastigophore	22–25	23.7	0.86	3–6	4.35	0.67	20	0	1/2
	Column	Basitrich	14.78–22	18.38	1.62	1.88–3.04	2.48	0.49	50	20	2/2
	Filament	Basitrich	10–26.31	17.01	4.95	1.98–3.11	2.29	0.34	17	20	2/2
		Microbasic p -mastigophore	16.15–29	21.04	1.96	2–6.57	3.4	0.83	50	22	2/2
	Tentacle	Basitrich	25–36	30.58	2.20	2–3	2.79	0.31	50	20	2/2
		Spirocyst	14–34.29	23.51	4.82	2–3.41	2.81	0.35	50	20	2/2
	Actinopharynx	Basitrich	13–32	23.75	4.9	2–4	3.23	0.66	50	20	2/2
Stichodactyla helianthus	Column	Basitrich	13–29.68	18.43	2.19	2–4	2.94	0.28	50	22	2/2
	Filament	Basitrich	11.88–17	14.1	1.08	1.7–3	1.98	0.17	50	20	2/2
		Basitrich	23–33	29.11	2.46	2–4	2.74	0.51	50	20	2/2
		Microbasic p -mastigophore	23.96–28.35	26.29	0.95	4.62–5.64	5.28	0.27	0	20	1/2
	Tentacle	Basitrich	8–16.92	11.47	1.83	1.6–3.2	2.30	0.42	50	20	2/2
		Microbasic p -amastigophore	13.6–40.12	27.08	3.87	3.2–5.71	4.14	0.45	50	20	2/2
		Spirocyst	10.4–26.84	17.74	3.21	1.6–6.4	3.79	0.91	50	20	2/2
	Actinopharynx	Basitrich	9.6–27.2	17.62	3.16	1.6–3.88	2.55	0.52	50	9	2/2
		Microbasic p -amastigophore	13.6–33.08	25.81	4.5	2.4–5.28	4.29	0.67	50	20	2/2
	Column	Basitrich	8–16	11.66	1.80	1.6–4	2.49	0.5	50	0	1/2
Aiptasia pallida		Basitrich	11.2–16	13.63	0.99	4–4.8	4.06	0.21	50	0	1/2
		Microbasic p -amastigophore	16–20	17.91	0.96	2.4–5	4.22	0.49	27	23	2/2
	Filament	Basitrich	12.71–19.48	16.2	2.84	2.28–3.62	3.01	3.62	0	4	1/2
		Microbasic p -amastigophore	8–14.4	11.74	0.98	1.93–4.14	3.22	0.35	50	20	2/2
		Microbasic p -amastigophore	20.58–35.98	29.24	2.74	4–9.96	5.21	0.85	50	21	2/2
	Acontia	Basitrich	22.02–28.8	25.83	1.39	2.11–3.2	2.86	0.37	50	20	2/2
		Microbasic p -amastigophore	60.8–71.28	65.96	2.3	7.2–10.81	8.92	0.6	50	20	2/2
Bartholomea annulata	Tentacle	Basitrich Microbasic p -amastigophore	10.89–24 35.2–47.2	19.36 40.87	2.87 2.76	1.86–3.29 5.34–8	2.91 6.58	0.36 0.73	50 50	20 20	2/2 2/2
		Spirocyst	12–30.75	19.89	4.89	1.6–4.8	3.05	0.83	50	20	2/2

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