Sertularella allmani Hartlaub, 1901

Horia R. Galea, Dirk Schories, Verena Häussermann & Günter Försterra, 2017, Taxonomic revision of the genus Sertularella (Cnidaria: Hydrozoa) from southern South America and the subantarctic, with descriptions of five new species, Revue suisse de Zoologie 124 (2), pp. 255-321 : 256-260

Sertularella allmani Hartlaub, 1901

Figs 1A, B , 2 ; Table 1

Sertularella Allmani Hartlaub, 1901: 81 , pl. 5 figs 12, 13; pl. 6 figs 1, 8 (replacement name for Sertularia secunda Allman, 1888 ). – (?) Jäderholm, 1903: 283.

non Sertularella Allmani. – Jäderholm, 1905: 32, pl. 12 fig. 11 (= Sertularella subantarctica Galea , sp. nov.).

Sertularella allmani. – Hartlaub, 1905: 649, fig. O4. – Bedot, 1916: 199; 1918: 234. – Billard, 1924: 61. – El Beshbeeshy, 2011: 121, fig. 37F.

non Sertularella allmani. – Naumov & Stepanjants, 1962: 86 [= Sertularella gaudichaudi ( Lamouroux, 1824) ].

Sertularia secunda Allman, 1888 : pl. 25 figs 2, 2a, 2b (replacement name for Sertularia unilateralis Allman, 1888: 53 ). – Vervoort, 1972: 108, fig. 33 (reexamination of holotype).

non Sertularella secunda Kirchenpauer, 1884: 50 , pl. 15 figs 7, 7a [= Symplectoscyphus secundus ( Kirchenpauer, 1884) ].

Sertularia unilateralis Allman, 1888: 53 {non Sertularia unilateralis Lamouroux, 1824: 615 , pl. 90 figs 1-3 [= Symplectoscyphus unilateralis ( Lamouroux, 1824) ]; non Sertularia unilateralis Allman, 1885: 139 , pl. 13 figs 5-7 [= Amphisbetia bispinosa ( Gray, 1843) ]}.

(?) Sertularella paessleri Hartlaub, 1901: 80 , pl. 6 figs 3, 19. – Hartlaub, 1905: 654, fig. S4.

Sertularella mediterranea asymmetrica Millard, 1958: 191 , fig. 7B. – Millard, 1964: 45. – Millard, 1975: 295, fig. 96A [non Sertularella mediterranea Hartlaub, 1901 ].

Sertularella antarctica . – Blanco, 1963: 170, figs 5, 6. – Stepanjants, 1979: 84, pl. 15 fig. 3. – Blanco, 1994: 198. – Galea et al., 2009: 7, figs 2J-N, 3A-B [non Sertularella antarctica Hartlaub, 1901 ].

Material examined: ZMH C04177; Chile, Región de Magallanes y de la Antártica Chilena, Isla Navarino, west of Puerto Pantalón del Weste, ca. 12 m, coll. Michaelsen no. 180; 31.12.1892; several fertile fragments (only part of the whole sample examined herein), up to 3.8 cm high, largest with accessory tubes on stem. There is obviously a crossing-out in the ZMH catalogue for this material: although it bears the official no. 180, it was indicated as no. 189 by Hartlaub (1901), as both share the same collection data. However, no. 189 corresponds to another specimen, ZMH C04178, assignable to S. picta ( Meyen, 1834) . As indicated by Hartlaub, the material is well-preserved and fertile. Since the 2nd specimen (from Port Stanley, Falkland Is., coll. Paessler, 12.04.1893) on which S. allmani was equally based upon was destroyed during WWII (H. Roggenbuck, pers. comm.), the specimen ZMH C04177 is designated here as the lectotype of S. allmani . – NHML 1888.11.13.101; French Southern and Antarctic Lands, Kerguelen Is., ca. 36 m, coll. Challenger; holotype of Sertularia secunda Allman, 1888 (= Sertularia unilateralis Allman, 1888 ), three male colony fragments (3.0, 1.5 and 1 cm high) in ethanol, as well as two slides; one slide ( Fig. 1B ), labeled “type” contains a 1.1 cm high, fertile colony fragment, and bears the mention “Challenger Stat 149D, Kerguelen, Depth 20 faths, Sertularia secunda ( unilateralis ) ”; the second slide ( Fig. 1A ) is a 1.7 cm high, fertile, branched colony fragment and bears the label “Challenger Coll., Sertularella secunda (Allman) , Kerguelen (d. 20 fms), B. carm.”. – MHNG- INVE-62835; Chile, Región de los Lagos, south of Isla Yencouma (south Chiloé), -42.40958° -74.08353°, 8 m, coll. HSFS, HF6, lot A521; 24.02.2008; several stems up to 1.6 cm high bearing male gonothecae. – HRG- 0637; Chile, Región de Magallanes y de la Antártica Chilena, Islotes Gemelos, -54.91942° -67.36308°, 13 m, coll. HSFS, HF9, lot C132; 15.12.2010; several stems up to 5 cm high, richly bearing either male or female gonothecae, the latter with acrocysts. – HRG- 0314; Chile, Región de los Ríos, Corral, La Amistad (San Carlos), -39.85744° -73.44024°, 5-10 m, coll. D. Schories, pooled lots 0 2 and 06; 26.05.2011; colony on seaweed, composed of many stems up to 4.3 cm high, bearing male gonothecae. – HRG-0634; Chile, Región de los Ríos, north of Corral, Chaihuin, -39.95730° -73.60245°, 6-12 m, coll. D. Schories; 27.10.2011; profuse colonies with up to 5 cm high stems, bearing either male or female gonothecae, the latter with acrocysts. – HRG-0644; Chile, Región de los Ríos, north of Corral, Chaihuin, -39.95730° -73.60245°, 6-12 m, coll. D. Schories; 27.10.2011; male colony on seaweed, composed of numerous stems up to 5 cm high. – HRG-0636; Chile, Región de los Ríos, Niebla, Bonifacio, -39.69002° -73.37940°, 10-15 m, coll. D. Schories; 09.10.2012; numerous colonies on seaweed, with up to 3.5 cm high stems, bearing either male or female gonothecae, the latter with acrocysts.

Description: Creeping, branching, anastomosing stolons giving rise to erect, bushy, irregularly-pinnate colonies, up to 6 cm high. Stems either mono- or lightly fascicled basally; in the first case, with 2-5 twists above origin from stolon. Both stems and branches divided into regularly-short, almost collinear internodes by means of deep, slightly oblique constrictions of the perisarc; the latter typically dark-brown at nodes, and almost transparent elsewhere; each internode with slight bulges at each end, and distally bearing a hydrotheca, or a hydrotheca and a lateral apophysis arising immediately from below its base. Hydrothecae, apophyses and side branches shifted on to one side of the colony at an acute angle, giving it two obvious, frontal and dorsal sides, respectively. Branching profuse, with a general, characteristic pattern: a couple of two consecutive, alternate side branches is separated from the next couple of branches by 1-2 (occasionally 0) internodes devoid of apophyses; occasionally, only one branch of a “pair” occurs ( Fig. 2C ); there are up to 3rd order branches. Hydrothecae biseriate, alternate, flask-shaped, moderately-long, adnate for about 1/3rd of their length, distinctly swollen adaxially, narrowing below aperture; abaxial wall nearly straight, free adaxial wall sigmoid, convex for most of its length, becoming concave a short distance below the aperture; rim thickened, provided with four, unequal cusps (abaxial one conspicuously produced, adaxial one the shortest, and the laterals asymmetrical and of intermediate length, the “anterior” one comparatively shorter than its “posterior” counterpart); cusps separated by deep, rounded embayments; 3 internal, submarginal cusps (2 latero-adaxial, 1 abaxial), not always present; operculum composed of 4 triangular flaps forming a conical roof. Gonothecae borne on both stems and side branches, arising from below the hydrothecal bases; broadly ovoid, with 6-8 transverse ridges, not always distinct; distally a short neck provided with generally 4 (occasionally 2-5) blunt projections of perisarc surrounding a central, rounded aperture; acrocysts in female. Perisarc of colonies either thin or thick.

Dimensions: See Table 1.

Remarks: When Allman (1888) realized that his Sertularia unilateralis (main text, p. 53) was a homonym (of Sertularia unilateralis Lamouroux, 1824 and Sertularia unilateralis Allman, 1885 ), he introduced the replacement name Sertularia secunda (legend of pl. 25, figs 2, 2a, 2b). However, Hartlaub (1901) correctly placed Allman’s species in the genus Sertularella Gray, 1848 and noted that, there, it becomes a junior synonym of Sertularella secunda Kirchenpauer, 1884 (the latter is now assigned to the genus Symplectoscyphus Marktanner-Turneretscher, 1890 ). He therefore introduced a second replacement name, viz. S. allmani .

Calder (2015, p. 239, note 39), influenced by the opinion originally expressed by Vervoort (1972) and subsequently followed by Galea et al. (2009), decided to reject as invalid the binomena Sertularia unilateralis Allman, 1888 (a species of Sertularella Gray, 1843 ), its replacement name Sertularia secunda Allman, 1888 and, in turn, its replacement name Sertularella allmani Hartlaub, 1901 , in the belief that all were synonyms of the frequently reported Sertularella antarctica Hartlaub, 1901 and its senior objective synonym Sertularella unilateralis Allman, 1876 (Calder, pers. comm.). However, in light of the present study, S. allmani is considered as a valid species, distinct from S. antarctica (see also remarks under the latter). Consequently, Calder’s (2015) suggestion, according to which a “case could be made (ICZN Art. 59.3.) for retention of Sertularella secunda Allman, 1888 [sic!] as the valid name of the species”, resurfaces, but it appears today to not carry enough weight according to the requirements of the Code. Indeed, Art. 59.3. stipulates that Sertularia secunda Allman, 1888 , as a junior secondary homonym of Sertularella secunda Kirchenpauer, 1884 , and replaced before 1961, be permanently invalid unless the substitute name, Sertularella allmani Hartlaub, 1901 , is not in use and the relevant taxa are no longer considered congeneric ( Sertularia secunda Allman, 1888 belongs actually to Sertularella Gray, 1843 , and Sertularella secunda Kirchenpauer, 1884 to Symplectoscyphus Marktanner- Turneretscher, 1890), in which case the junior homonym is not to be rejected on grounds of that replacement. In light of the synonymy given above, it appears that the binomen S. allmani was used more often than S. secunda . Consequently, Hartlaub’s (1901) S. allmani is retained as the valid name of the species.

The typical shape of the colonies of S. allmani is illustrated by Galea et al. (2014, pl. 3D, as S. antarctica ), while several gonothecae are depicted by Galea et al. (2009, fig. 3B, as S. antarctica ). The branching pattern in this species is irregularly pinnate. In some parts of very profuse colonies, nearly all internodes give rise to alternate side branches, although in more sparingly branched ones, there is a tendency to form groups of two consecutive, alternate side branches separated by 1-2 stem internodes devoid of apophyses. Occasionally, though not rarely, more irregular side branches, separated by a varied number of internodes with no apophyses, may arise successively on the same side of the stem.

In all specimens from Chile, the stems are monosiphonic in habit, and give rise to side branches of up to 3rd order. Polysiphonic stems were reported only in rare instances [ Hartlaub 1901, as both S. allmani and S. paessleri (see below for the taxonomic status of the latter)]. The perisarc of the colonies (including the hydrothecae) may be either thin (as in the Chilean material) or thick ( Hartlaub, 1901; Blanco, 1963, as S. antarctica ). The hydrothecal margin is always thickened, and the abaxial marginal cusp is generally distinctly produced, though its length may vary among various colonies, or even within the same stem. The gonothecae of both sexes are either distinctly transversely ringed (e.g. HRG-0637, HRG-0644), or only wrinkled to nearly smooth (e.g. HRG-0634, HRG-0636). Material of Sertularella paessleri Hartlaub, 1901 is no longer extant in collections of ZMH (H. Roggenbuck, pers. comm.). However, Hartlaub emphasized the large size and the smooth appearance of the gonothecae in the obviously young colony available. Otherwise, the characters of the trophosome alone (branching almost regularly pinnate, with consecutive, alternate “pairs” of side branches separated by 2 internodes devoid of apophyses; invariably short internodes; short, adaxiallyswollen hydrothecae shifted on to one side, and adnate for 1/3rd their length; abaxial cusp produced; rim thickened) agree well with the present concept of S. allmani , including the presence of fascicled stems, as those observed in the lectotype, ZMH C04177.

The variety asymmetrica , created by Millard (1958) for a hydroid assigned to S. mediterranea Hartlaub, 1901 , is likely conspecific with the present species. Although all her specimens were represented by small, unbranched stems, their microscopic structure displays all the distinctive characters of S. allmani , notably: short internodes, thick-walled hydrothecae conspicuously shifted on to one side of the stem, a produced abaxial cusp, the noteworthy asymmetry of the laterals, as well as the presence of 3 internal, submarginal cusps.

Distribution: Chile – Región de los Ríos [around Corral ( Galea & Schories, 2012a, as S. antarctica )]; Región de los Lagos [south of Isla Grande de Chiloé ( Galea et al., 2009, as S. antarctica )]; Región de Magallanes y de la Antártica Chilena [west of Puerto Pantalón del Weste, Isla Navarino ( Hartlaub, 1901; 1905); Islote Gemellos (present study); Magellan Strait (? Jäderholm, 1903)]. Argentina – Provincia de Santa Cruz [Punta Peñas, San Julián ( Blanco, 1963; 1994, both as S. antarctica )]. Falkland Is. – Port Stanley ( Hartlaub, 1901; 1905); Port Williams ( Hartlaub, 1901; 1905, both as S. paessleri ). French Southern and Antarctic Lands, Kerguelen Is. – off Accessible Bay [ Allman 1888, as Sertularia secunda (= Sertularia unilateralis )]. South Africa – Millard (1958; 1964; 1975, all as S. mediterranea var. asymmetrica ).

Figures

Fig. 1. (A, B) Sertularella allmani Hartlaub, 1901. Two holotype slides of Sertularia secunda Allman, 1888 (= Sertularia unilateralis Allman, 1888). (C) Sertularella blanconae El Beshbeeshy, 2011, material identified as S. gayi (Lamouroux, 1821) by Jäderholm (1903). (D) Sertularella clausa (Allman, 1888), holotype slide. (E, F) Sertularella contorta Kirchenpauer, 1884 identified as S. polyzonias (Linnaeus, 1758) by Jäderholm (1910) (E) and S. lagena Allman, 1876 by Stechow (1925) (F), respectively. (G) Slide material studied by Jäderholm (1905), containing S. contorta (colony on the left-hand side) and S. subantarctica Galea, sp. nov. (colony on right-hand side), the latter identified by him as S. allmani. (H-K) Sertularella gaudichaudi (Lamouroux, 1824). Slide materials identified as S. picta (Meyen, 1834) (H), S. antarctica Hartlaub, 1901 (I) and S. protecta Hartlaub, 1901 (J) by Jäderholm (1903); as S. protecta by Stechow, according to Rees & Thursfield (1965) (K).

Fig. 2. Sertularella allmani Hartlaub, 1901. Colony fragments from lectotype (A) and material MHNG-INVE- 62835 (B). Mode of branching (C). Hydrothecae from the lectotype of S. allmani (D), the holotype of Sertularia secunda Allman, 1888 (= Sertularia unilateralis Allman, 1888) (E, alcohol-preserved material; F, 2 nd slide), and materials HRG- 0314 (G), HRG- 0637 (H) and HRG- 0644 (I). Scale bars: 200 μm (D-I), 1 mm (A, B).