Notes on some sertulariid hydroids (Cnidaria: Hydrozoa) from the tropical western Pacific, with descriptions of nine new species Author Galea, Horia R. text European Journal of Taxonomy 2016 2016-08-02 218 1 52 journal article 21896 10.5852/ejt.2016.218 cba502b0-cc06-4252-94f1-3eda754e8183 2118-9773 3840195 A4D7AA38-D18F-4604-A5E0-D965637BD9F8 Sertularella plicata sp. nov. urn:lsid:zoobank.org:act: 5CBEB7F6-12F7-403C-AC8D-58AE01B11AC7 Fig. 8 L–O; Table 3 Diagnosis Small Sertularella with monosiphonic stems; side branches given off irregularly in one plane. Internodes moderately long and geniculate. Hydrothecae piriform, with 8–10 conspicuous, transverse ribs; aperture on short, narrow neck facing outwards; 3 or 5 internal, submarginal, lamellar cusps. Gonothecae unknown. Fig. 8. (previous page) ― A–G . Sertularella folliformis sp. nov. (BATHUS 3, Stn. DW809). A . Holotype. B . Paratype. C . Portion of stem with proximal part of a side branch. D . Successive internodes with their hydrothecae. E . Hydrothecal aperture, frontal view, showing internal cusps. F . Portion of stem with gonotheca, showing insertion site. G . Gonotheca. ― H . Sertularella helenae Vervoort, 1993 (SALOMON A, Stn. DW1714), two successive internodes with their hydrothecae. ― I . Sertularella paucicostata Vervoort, 1993 (BATHUS 3, Stn. DW809), two consecutive internodes with their hydrothecae, and comparison with Sertularella costata Leloup, 1940 (J–K). ― L–O . Sertularella plicata sp. nov. (MUSORSTOM 3, Stn. CP121). L . Portion of stem and proximal part of a side branch. M . Two consecutive internodes with their hydrothecae. N . More detailed view of the hydrotheca, to show its wrinkled surface. O . Hydrothecal aperture in frontal view, showing internal cusps. ― P–S . Sertularella aff. sinensis Jäderholm, 1896 . P . Portion of stem (BATHUS 3, Stn. DW829). Q . Hydrotheca (BORDAU 2, Stn. DW1595). R . Frontal view of three hydrothecal apertures, to show variation in the number of internal cusps. S . Gonotheca (BORDAU 2, Stn. DW1595). Scale bars: A–B = 1 cm; C, F–G, L, P = 1 mm; D, H–J, M, Q, S = 500 µm; E, K, O, R = 100 µm; N = 200 µm. Etymology From the Latin plĭco , -ātum , -āre (and the Greek πλέχω ), meaning “pleat, pleated, to pleat”, to characterize the appearance of the external surface of the hydrothecal wall. Material examined Holotype MUSORSTOM 3: Stn. CP121, colony composed of several sterile stems up to 1 cm high, epizoic on dead gorgonian (MNHN-IK-2012-16576). Description Colony composed of up to 1 cm high, monosiphonic stems arising from creeping, branching hydrorhiza. Basal parts of stems of varied length and ahydrothecate, perisarc smooth; above, stems divided into regular, moderately long, geniculate internodes, by means of slightly oblique nodes slanting in alternate directions; each internode with one, distal hydrotheca. Side branches arising irregularly from below the bases of stem hydrothecae and in the same plane as the stem; from one to several hydrothecae between two successive side branches; up to second order branching observed; structure identical to that of stem, except for the first internode, which is comparatively longer than following ones; distal-most, tendril-like internodes occasionally anastomose with each other or with neighboring stems. Hydrothecae swollen basally, then narrowing gradually distally to a short neck region projecting the aperture slightly outwards; adaxial side less than ½ adnate; walls with 8–10 conspicuous transverse ridges encircling the theca; numerous creases, perpendicular to the ridges, give the hydrotheca a wrinkled appearance; aperture rhomboidal, rim with four blunt cusps separated by shallow embayments; opercular apparatus composed of four triangular valves forming a low roof; 3 or 5 internal, submarginal, lamellar cusps (two latero-adaxial and one adaxial and, in some hydrothecae, two additional, latero-adaxial ones). Gonothecae not observed. Remarks Hydrothecae with such deep, transverse ridges are present in a number of congeners, but several distinctive features allow their separation from the new species: 1) S. areyi Nutting, 1904 , but its hydrothecae are provided with only 2–3 transverse ridges ( Fig. 7J ); 2) S. costata Leloup, 1940 is a much smaller hydroid (compare Fig. 8J and 8M ); 3) S. crenulata Nutting, 1905 possesses a considerable number of closely-set, transverse ridges, and its hydrothecae are tronconical ( Vervoort 1993 ); 4–6) S. helenae Vervoort, 1993 ( Fig. 8H ), S. paucicostata Vervoort, 1993 ( Fig. 8I ) and S. pseudocostata Vervoort, 1993 , but their hydrothecae are larger and more tubular; 7) S. fraseri Galea, 2010 is a more delicate hydroid and its hydrothecae are provided with fewer ridges; 8) S. quadrata Nutting, 1895 has densely-striated, exceedingly long and tubular hydrothecae, with characteristically squared cross-section ( Nutting 1904 ); 9) the hydrothecae of S. sinensis Jäderholm, 1896 are only half adnate, and the number of ridges they carry reaches as many as 15 in the northern hemisphere ( Naumov 1969 ); 10) S. striata Stechow, 1923 , but in this species the internodes are comparatively shorter, almost collinear, and the hydrothecae are less fusiform and only about half adnate ( Millard 1964 ). Geographical distribution Philippines .