Anthopleura mariscali, Daly & Fautin, 2004

Daly, Marymegan & Fautin, Daphne G., 2004, Anthopleura mariscali, a new species of sea anemone (Cnidaria: Anthozoa: Actiniaria) from the Galápagos Islands, Zootaxa 416 (1), pp. 1-8 : 2-7

Anthopleura mariscali new species

Figures 1–3

Material examined. Pacific Ocean, Galápagos Islands, Santa Cruz Island , Turtle Cove , 0°29’37” S, 90°19’41” W, intertidal, Coll. R . N. Mariscal , 14 February 1964, preserved in formalin, stored in 70% ethanol, KUNHM 1851 , holotype. Paratypes collected at the same time and place: CAS 168009 , KUNHM 1852 , USNM 1019899 . Pacific Ocean, Galápagos Islands, Santa Fe Island , 0°48’00” S, 90°02’13” W, intertidal, Coll. R . N. Mariscal , 5 February 1964, preserved in formalin, stored in 70% ethanol, KUNHM 1855 . Pacific Ocean, Galápagos Islands, Plaza Island Sur, West End , 0°34’46” S, 90°10’03” W, intertidal, Coll. R . N. Mariscal , 8 February 1964, preserved in formalin, stored in 70% ethanol, CAS 168010 , KUNHM 1856 . Pacific Ocean, Galápagos Islands, Plaza Island Sur, North Side , 0°34’51” S, 90°09’47” W, intertidal, Coll. R . N. Mariscal , 8 February 1964, preserved in formalin, stored in 70% ethanol, KUNHM 1859 . Pacific Ocean, Galápagos Islands, Santa Cruz Island , north­east, 0°35’18” S, 90°10’28” W, intertidal, Coll. R . N. Mariscal , 10 February 1964, preserved in formalin, stored in 70% ethanol, KUNHM 1853 . Pacific Ocean, Galápagos Islands, Santa Cruz Island , north­east of Point Bowditch , 0°31’02” S, 90°28’29” W, intertidal, Coll. R . N. Mariscal , 19 February 1964, preserved in formalin, stored in 70% ethanol, KUNHM 1854 , USNM 1019900 .

Diagnosis. Actiniidae with endocoelic adhesive verrucae from margin to limbus. Margin with long, endocoelic, fingerlike projections, each with an acrorhagus on the oral surface and verrucae on the adoral surface ( Figure 1 ). Column orange to pink, darker distally than proximally, some individuals with broad opaque white markings on the distal endocoelic spaces, giving the column a striped appearance ( Figure 1A ).

Column. Column approximately twice as wide in diameter distally as proximally in live specimens; column typically 7 mm long, oral disc diameter of 15 mm, pedal disc diameter approximately 7 mm. In preserved specimens, oral disc and pedal disc roughly same diameter, 4–11 mm (7 mm in holotype); column height 3–10 mm (6 mm in holotype). Contracted specimens often dome­shaped. Column covered from margin to just above limbus with simple, endocoelic, adhesive verrucae arrayed in regular longitudinal series ( Figure 1 ); those of primary and secondary endocoels more numerous and extend further proximally compared to those of higher­order endocoels. Verrucae more prominent distally than proximally; same color as column; cup­shaped; to 0.5 mm in diameter ( Figure 2D ); hold stones and shell debris in life. Margin denticulate, with prominent endocoelic marginal projections, those of primary and secondary endocoels larger, more prominent than others; each projection typically bears three or more large verrucae on its adoral surface and a single acrorhagus on its oral surface ( Figure 2A ). Most marginal projections of most specimens bear an acrorhagus, although acrorhagi not present on all marginal projections of all specimens, and a rare higher­order endocoel lacks a marginal projection.

Color orange­pink proximally, darker distally. Typically, each endocoelic space frosted distally with opaque white longitudinal stripe extending approximately one­quarter column length. Color of preserved specimens grayish­tan to peach, distal column typically darker than proximal column, frosting not visible. Acrorhagi opaque white. Tips of marginal projections in some preserved specimens spotted with dark pigment ( Figure 1B ).

Oral Disc and Tentacles. Inner tentacles longer than outer, typically held erect; outer tentacles point basally. In life, each tentacle tapers to blunt point, which is perforate ( Figure 2B ). Tentacles number 40–100, depending on size of animal (46 in holotype).

Oral disc brownish, mesenterial insertions visible as pale lines. Actinopharynx creamy white. Mouth typically same color as column, prominent, rounded, elevated on oral cone in center of disc. Tentacles paler than oral disc, some with reddish cast on oral surface; with longitudinal green stripe that may extend onto oral disc. In preservation, tentacles translucent gray brown, typically without markings, although tips and distalmost oral surface of tentacles of some specimens marked with dark pigment ( Figure 1B ).

Internal Anatomy. In specimens lacking regeneration scars, two siphonoglyphs, each of which attaches to a pair of directive mesenteries; in those with scars, directives or siphonoglyphs may be lacking or occur in greater numbers than in specimens without scars. Siphonoglyph prolonged aborally. Mesenteries hexamerously arranged, in three or four cycles; larger mesenteries perfect. Arrangement of mesenteries obscured in specimens that have regeneration scars. Gonochoric. All perfect mesenteries, except those attached to siphonoglyphs, fertile; imperfect mesenteries and those attached to siphonoglyphs sterile.

Marginal sphincter muscle strong, symmetrical, palmate, with many secondary branches ( Figure 2C ). Parietobasilar muscle diffuse, large, with narrow, short pennon ( Figure 2E ). Mesenterial lamella between retractor and parietal without folds or branches; no accessory muscles. Retractor muscles circumscribed, strong, almost reniform.

Cnidom. Spirocysts, basitrichs, holotrichs, microbasic b ­mastigophores, microbasic p ­mastigophores ( Figure 3 ). See Table 1 for size and distribution.

Distribution. In cracks and crevices, high to low intertidal zone, Galápagos Archipelago, Pinzón Island, Plaza Island Sur, and Santa Cruz Island. Not seen subtidally. Likely clonal: many specimens have regeneration scars and anatomical irregularities, and individuals live in close physical proximity.

Etymology. Anthopleura mariscali is named for Dr. Richard N. Mariscal, in recognition of his numerous contributions to the study of cnidarians. Dr. Mariscal participated in the GISP, when he collected the specimens designated as the types of Anthopleura mariscali .

Differential diagnosis. In the Galápagos, Anthopleura mariscali occurs in the same intertidal habitats as A. nigrescens ( Verrill, 1928) , a species widespread in the tropical Indo­Pacific ( Dunn 1974, England 1987). These two species differ in habitat, color, anatomy, and cnidom. In the field, the two can be distinguished based on coloration: a member of A. mariscali has an orange to pink column that is darker distally and typically frosted with white at the margin, whereas a member of A. nigrescens is purple­black or deep green with pale verrucae, lacking frosted white markings distally. The two differ in habit as well; members of A. mariscali live in small cracks and crevices and adhere strongly to the substrate whereas members of A. nigrescens live less firmly attached on the surface of the substrate. The verrucae of A. mariscali are typically less adherent than those of A. nigrescens : when disturbed, a specimen of A. mariscali typically releases adherent gravel whereas one of A. nigrescens typically retains it. Preserved specimens of A. mariscali are typically paler than those of A. nigrescens , and the column often remains two­toned, with a gray distal half and a pale orange or tan proximal half. A preserved specimen of A. nigrescens is typically a uniform reddish­brown, becoming paler over time. These two species can also be distinguished based on cnidae size ( Table 1 ), and by musculature: the retractor muscle of A. mariscali is more compact than that of A. nigrescens , and lacks a free flap (= pennon), and the sphincter muscle of A. mariscali is nearly symmetrical, rather than more developed on the adoral side as in A. nigrescens .

Other similar species. No described species of Anthopleura has the coloration pattern characteristic of A. mariscali , but in having opaque white patches on the distal column, A. mariscali recalls the common European species Bunodactis verrucosa ( Pennant, 1777) and a population of the widespread species Bunodosoma granulifera ( LeSueur, 1817) described from the Bahamas as Bunodes taeniatus McMurrich, 1899 . However, the markings that create the stripes differ among these species: in B. verrucosa , the stripes result from the color of the verrucae themselves, rather than from streaks over both the verrucae and the column wall as in A. mariscali (MD pers. obs.). Drawings accompanying the description of B. taeniatus (Figure 4: McMurrich 1899) indicate that the lighter regions include several endocoelic spaces and the exocoels between them; in A. mariscali , each white streak covers a single endocoel.

In having a column that is darker distally than proximally, A. mariscali resembles Actiniogeton spenceri ( Haddon & Duerden, 1896) and two species of Anthopleura : A. varioarmata Watzl, 1922 (see Carlgren 1952), a Panamic species, or Anthopleura dixoniana ( Haddon & Shackleton, 1893) , a species common in the Indo­Pacific. Actiniogeton spenceri , which is known only from southeast Australia, lacks holotrichs in the marginal structures (Carlgren 1938) and has a diffuse marginal sphincter ( Haddon & Duerden 1896), unlike A. mariscali which has holotrichous acrorhagi and a strong, circumscribed marginal sphincter. Anthopleura mariscali differs from both A. varioarmata and A. dixoniana in the color of the column and in the size of the holotrichs of the acrorhagi: the acrorhagial holotrichs are larger in A. mariscali than in either A. varioarmata (see Belém & Monteiro, 1981) or A. dixoniana (see England 1987). The retractor muscle is more diffuse in A. varioarmata than in A. mariscali . Unlike A. mariscali , A. dixoniana is zooxanthellate, and has a maximum known tentacle number of 60 ( England 1987).

Figures

FIGURE 1. External morphology of Anthopleura mariscali, new species. Scale bar = 0.5 mm. A. Partially contracted live specimen. Note striped appearance of distal column and well­expanded marginal projections with verrucae. Photograph by C. P. Hickman, Jr. B. Holotype. Note spots of dark pigment on tips of some tentacles and marginal projections.

FIGURE 2. anatomy and histology of Anthopleura mariscali, new species. A. Longitudinal section through a marginal projection. Each projection bears an acrorhagus (A) on the oral surface and several verrucae (V) on the adoral surface. F, fosse. Scale = 0.5 mm. B. Longitudinal section through tip of a tentacle, showing apical pore (arrow). Scale = 30 m. C. Cross section of marginal sphincter muscle. Scale = 50 m. D. Longitudinal section through a verruca. Scale = 60 m. E. Cross section through mesentery proximal to actinopharynx, showing retractor muscle (R) and parietal muscle (P). Arrow indicates pennon of parietobasilar muscle. Scale = 90 m.

FIGURE 3. Representative cnidae from Anthopleura mariscali, new species. Scale bar = 20 m; refer to Table 1 for size and distribution. A. Spirocyst. B. Basitrich. C. S­shaped basitrich. D. Small basitrich. E. Microbasic b­mastigophore I. F. Microbasic b­mastigophore II. G. Microbasic p­mastigophore. H. Holotrich I. I. Holotrich III. J. Holotrich II.