Phymanthus pinnulatus Martens in Klunzinger, 1877

Yap, Nicholas Wei Liang, Tan, Ria, Yong, Clara Lei Xin, Tan, Koh Siang & Huang, Danwei, 2019, Sea anemones (Cnidaria, Actiniaria) of Singapore: redescription and taxonomy of Phymanthuspinnulatus Martens in Klunzinger, 1877, ZooKeys 840, pp. 1-20 : 1

Phymanthus pinnulatus Martens in Klunzinger, 1877 Figs 2, 3, 4, 5, 6, 7

Phymanthus pinnulatum Martens in Klunzinger, 1877: 87 (original description).

Phymanthus pinnulatum : Haddon 1898: 496; Carlgren 1949: 75.

Phymanthus pinnulatus : Fautin 2016: 346.

Occurrence and materials collected in Singapore

(Fig. 1). (* - observed alive; bold - morphotypes with smooth marginal tentacles or reduced protuberances):

Berlayer Creek (ZRC.CNI.1343 x4*), Big Sister’s Island (ZRC.CNI.0982 x1; ZRC.CNI.1103 x1*; ZRC.CNI.1163 x1*; ZRC.CNI.1045 x1*; ZRC.CNI.1347 x4*), Changi East Beaches (ZRC.CNI.1084 x1*; ZRC.CNI.1106 x1*), Chek Jawa (photographed but not collected), Cyrene Reef (ZRC.CNI.1089 x1*; ZRC.CNI.1112 x2*; ZRC.CNI.1145 x1*; ZRC.CNI.1342 x4*), East Coast Park Beaches (ZRC.CNI.1039 x1*; ZRC.CNI.1046 x1*; ZRC.CNI.1110 x1*), Kusu Island (ZRC.CNI.1162 x1*), Pulau Hantu (ZRC.CNI.0015 x1; BMNH1995.1006 x1; CASIZ161242 x1), Pulau Jong (BMNH1996.355 x1), Pulau Sekudu (ZRC.CNI.0738 x1), Pulau Semakau (ZRC.CNI.1031 x1*; ZRC.CNI.0318 x1; ZRC.CNI.0321 x1; ZRC.CNI.0322 x1; ZRC.CNI.0639 x1; ZRC.CNI.1098 x1*; ZRC.CNI.1361 x1*), Pulau Tekukor (ZRC.CNI.0993 x3*, of these only one has reduced protuberances; BMNH1996.313 x1; ZRC.CNI.1306 x1*), Sentosa (Tanjong Rimau) (ZRC.CNI.1345 x4*), St John’s Island (ZRC.CNI.0467 x1), Tanah Merah (photographed but not collected), Terumbu Bemban (ZRC.CNI.1223 x1*), Terumbu Pempang Tengah (ZRC.CNI.1028 x1*; ZRC.CNI.1029 x1*), Terumbu Raya (ZRC.CNI.1111 x1*), Terumbu Semakau (ZRC.CNI.0493 x1).

Type material examined.

Holotype, ZNB Cni 1324, collected by E. von Martens. A single specimen, 60 mm in length, flaccid, cut longitudinally, a slice of the distalmost margin and part of the proximal end missing, though a little of the pedal disc remains, cream-coloured entirely (Fig. 2A); NRS76 consists of three pieces originating from ZMB Cni 1324 (see Fautin 2016), all pieces cream-coloured in preservative: a piece of the distalmost end with oral disc and marginal tentacles present, 11 mm in length; a piece of mesentery, fertile, 9 mm wide; a 30 mm longitudinal strip of the column (Fig. 2B).

Natural history.

Usually encountered during low tide, with upper portion exposed, oral disc and marginal tentacles expanded (Fig. 3A, B, C). Sediment and small shell fragments may adhere to verrucae (Fig. 3D). Lower body usually deep in crevices or buried in sand or coral rubble. Pedal disc attached to buried rock, fragments of shell or coral rubble. Retracts quickly and deeply into substratum when disturbed, pulling in marginal tentacles completely. Animal typically found singly, with multiple individuals separated by a short distance (> 20 cm), although clusters up to four have been observed. Zooxanthellate.

Marginal tentacles.

96 in total; one individual with 98 (ZRC.CNI.1342). All of similar length, equal to oral disc radius or longer (Figs 3A, B). Arranged hexamerously in four cycles but octamerously in one individual (ZRC.CNI.1029). Cycle closest to margin exocoelic; innermost cycles endocoelic. One per endo-/exocoel. Ramified protuberances occur laterally along both sides, symmetrical, alternating between large and small knobs (Fig. 4A). In life, branching appears extensive; when preserved, appears as low knobs (Figs 4A, B, respectively). Extent of branching may vary; some individuals have protuberances as slight bumps while in others the entire length is smooth (Figs 4C, D). Tip narrow and blunt, without perforation (Fig. 4E); base wide. Colour variable, from greenish-brown, slatey-grey to blue with golden tinge (Figs 3A, B, C); tip with green, purple, or pink cast. In fixed individuals, tentacles cream-coloured to greenish, translucent. Protuberances cream-coloured to gold on oral side; usually with a white line adjoining opposite protuberances (Fig. 4A).

Column.

Colour variable, from tan to translucent white. Distalmost end dark-brown. May appear whitish or cream-coloured in life, or with a light green tinge in preserved specimens. Distalmost end flared outwards when animal is expanded; mid-section uniform diameter; pedal end may spread outwards when animal is attached to a surface. Diameter of distalmost end greater than pedal disc. Marginal projections present along margin of distalmost end; may be inflated, perforated (Fig. 4F), with a central white dot. Dot not visible in preserved specimens. Longitudinal rows of adherent verrucae present, extending proximally to mid-section (Fig. 3D). In life, shell fragments or substratum particles may be attached to verrucae. Verrucae outline eye-shaped, as low white bumps, middle depressed, diameter <1 mm. Verrucae rows endocoelic; alternate long and short rows. Longer rows with typically more than eight verrucae; shorter rows with less than five. Mesenterial insertions seen as white lines that extend from distalmost to pedal end. Past mid-section: plain and smooth, without any obvious structures. Cinclides present, visible only when limbus is expanded. Fosse present, shallow, ca. 1 mm deep.

Oral disc.

Outline round, flat when fully expanded; diameter 40 mm or greater. Colour in life grey to dark brown, with white markings flanking outwards; in fixed specimens, cream-coloured to translucent white. Discal tentacles present, arranged in radial rows extending from mouth to marginal tentacles, both endo- and exocoelic, numerous in a row (Fig. 5A). Discal tentacles outline: slim oval, as low bumps (Fig. 5B), some with middle sunken in, dependent on state of expansion. Discal tentacles dark-brown or grey in life. In preserved individuals, these are very inconspicuous, seen as horizontally radiating short grey dashes (Fig. 5C), may be very faint, or not seen at all, depending on state and age of specimen (e.g. Figs 5C, D). Wall thin; dark lines corresponding to mesenterial insertions visible through wall, extends from the mouth to margin. Central mouth oval and flat, area around it may be translucent. Two siphonoglyphs, symmetrical. In life, these may be white with pinkish streaks. Preserved, siphonoglyphs appear cream-coloured.

Pedal disc.

Oval, flat, same colour as proximal section of column. Thin-walled, mesenterial insertions appear as radiating white lines. Strongly adherent; readily attaches to surfaces to follow contour of substratum.

Internal morphology.

Actinopharynx longitudinally pleated, extends proximally until mid-column. Oral and marginal stomata present. Mesenteries contain zooxanthellae, arranged in three orders. All 12 pairs of highest order complete, fertile and with filaments; two of these directives, each attached to a siphonoglyph. Mesenteries of second order incomplete, but all fertile with filaments, 12 pairs. In one individual (ZRC.CNI.0467) nine pairs of imperfect mesenteries were present in the second order. Twenty-four pairs of mesenteries small, without filaments and retractor pennon make up third order. All mesenteries, except smallest, extend to the proximal end. Sphincter muscle absent (Fig. 6A). Retractor muscles: strong, diffuse to diffuse circumscript. Parietobasilar muscle extends away from mesentery, as a reduced pennon (Fig. 6B), poorly developed. No internal broods encountered.

Cnidom.

Spirocysts, basitrichs, microbasic p-mastigophores (Table 1). Cnidae illustrated in Fig. 7. No cnidom data yielded from holotype (i.e., ZMB Cni 1324 and NRS 76), cnidae present damaged with crystalline appearance.

Distribution.

Singapore ( Klunzinger 1877; this study), Indonesia (pers. obs.; see discussion below) and Northern Australia (see discussion below).

Remarks.

Of the 53 specimens collected in this study and those examined in situ, we encountered five individuals having reduced protuberances. These morphotypes were only encountered along the southern Singapore shores.

While Klunzinger (1877) makes no mention of the etymology of the name, nor does it appear in Martens’ (1867, 1875) reports, the original species name is rendered as pinnulatum , made up of both a noun (pinnula = small wing) and a neuter, adjective forming suffix (-tum), thereby making it an adjective in the nominative singular (ICZN Article 11.9.1). Therein, the original spelling of the species name is incorrect. The species name, being an adjective in a genitive case, according to Article 31.2 of the International Code of Zoological Nomenclature (International Commission on Zoological Nomenclature 1999), must agree in gender with the genus. The gender of Phymanthus is masculine, therefore the species name is pinnulatus (see also Fautin 2016).