Eunephthya Verrill 1869

Genus Eunephthya Verrill, 1869

Eunephthya Verrill, 1869: 284; 1922: 28–30; Broch 1939: 61

Capnella Kükenthal 1906a: 67; Thomson 1910: 575 –580; Broch 1939: 61; Utinomi 1960: 30 –31; Verseveldt 1977 (part): 185; Williams 1988: 19 –26; 1992a: 328–335

Non Eunephthya: Kükenthal 1906a: 69; 1906b: 65–68; 1907: 317–381; Broch 1912a: 35 –43; 1912b: 19–21; 1928: 3–19; 1939: 61; Jungersen 1915: 1164 –1181; 1916: 9–18; Molander 1915: 11 –16, 45–47, 70–84, pl. 2; 1918: 11–18; Thorpe 1928: 510 - 514, pl. 31, 32; Deichmann 1936: 58 –66, pl. 4; Tixier-Durivault 1961: 248 –250

Type species. Nephthya thyrsoidea Verrill, 1865, by subsequent designation: Verrill 1869: 284

Diagnosis. Nephtheidae with upright, arborescent or bushy colonies with distinct stalk. Polyps grouped on catkins that may be arranged on short branches or lobes or may arise directly from unbranched stalk. Polyps contractile, club-shaped and typically curving inwards towards catkin axis. Polyps and polyparium surface heavily armed with flat rods, spindles, asymmetrical clubs, leaf clubs, and large irregular sclerite forms. Some unilaterally spinose or leaf spindles always present in abaxial (convex) surface of polyp, arranged with spines or leaves protruding from surface. Adaxial (concave) surface of polyp lacking sclerites or with spindles arranged transversely. Tentacles with spindles and flat rods. Sclerites of stalk surface are small radiates and tuberculate spheroids. Interior sclerites absent or of same form as stalk surface. Interior canal walls typically have thick mesoglea. Sclerites colorless.

FIGURE. 1. Maximum likelihood tree for combined analysis of mtMutS, COI and 28S rDNA gene regions. Values above branches are bootstrap values for ML analysis of combined dataset; values in italics below branches are bootstrap values for maximum parsimony analysis of combined dataset. Asterisk indicates node that is in conflict between analyses (see text); ns: bootstrap value <50. Shaded box shows species of Capnella from tropical waters.

FIGURE. 2. Capnella imbricata RMNH Coel. 38645; a, leaf clubs of polyp; b, leaf capstans from top of stalk; c, leaf capstans from base of stalk; d, tuberculate spheroids and irregular bodies from interior of stalk.

Distribution. Cold-water regions of southern South Africa, Cape Peninsula to northern Transkei, depth 10– 240 m (Williams 1992b).

Taxonomic History. In March 1869, Verrill described the genus Eunephthya (family Nephtheidae) to accommodate Nephthya thyrsoidea Verrill, 1865, a species from the Cape of Good Hope, South Africa. Simultaneously, he included in this genus E. glomerata Verrill, 1869, a species from Greenland. Kükenthal (1902) subsequently described a similar South African species as Nephthya rugosa, which he later transferred to Capnella (Kükenthal 1903). Recognizing the similarities between his and Verrill’s material, Kükenthal (1906: 82) also moved E. thyrsoidea to Capnella, a genus that takes priority over Eunephthya by one month. Kükenthal (1906) designated Verrill’s E. glomerata as the type species of Eunephthya, however, and incorporated into that genus a variety of other northern hemisphere genera, including Gersemia Marenzeller, Drifa Danielssen, and Duva Koren & Danielssen (for a historical discussion of subsequent views on the relationship between Eunephthya sensu Kükenthal and Gersemia, see Thorpe (1928)). Verrill (1922: 28) later disputed Kükenthal’s interpretation of Eunephthya, stating clearly that he had designated the South African N. thyrsoidea as the type of the genus, and recommending that the name not be applied to northern hemisphere species, including E. glomerata which he now referred to Drifa. Subsequent authors ignored Verrill’s recommendations, however, and continued to use Eunephthya sensu Kükenthal, 1906 for northern hemisphere species (Broch 1928, 1939; Deichmann 1936).

Verrill (1922: 29) considered Capnella rugosa (Kükenthal, 1902) to be a synonym of E. thyrsoidea, but he maintained the generic distinction between the South African species (Eunephthya) and Capnella, whose type species is Alcyonium imbricatum Quoy & Gaimard,1833, a zooxanthellate species from the tropical Indo-Pacific. Utinomi (1960, 1961) later revised both genera, retaining the southern hemisphere and Indo-Pacific species (including E. thyrsoidea) in Capnella, but reinstating Gersemia, Drifa, Duva and a new genus, Pseudodrifa Utinomi, 1961 to accommodate the northern hemisphere species. Verseveldt (1977) likewise included E. thyrsoidea within Capnella, and assigned to Capnella numerous additional species from both tropical and temperate southern hemisphere locations.

Remarks. Based on morphological distinctions and supported by molecular phylogenetic data, the species currently included within Capnella can be divided among three or four distinct clades (Fig. 1). The cold-water species from southern South Africa constitute one well-supported clade (Fig. 1), for which we reinstate the genus Eunephthya. Zooxanthellate, tropical species of Capnella from the Indian Ocean and Great Barrier Reef of Australia fall into a separate, well-supported clade (Fig. 1). Eunephthya is easily distinguished morphologically from the tropical Capnella species by the sclerites found in the interior of the stalk, which in Capnella are large ovals and irregular forms (Verseveldt 1976, 1977) (Fig. 2). In Eunephthya the interior sclerites (if present) are small radiates and spheroids of the same type found in the stalk surface (Figs. 5–17).

Molecular phylogenetic analyses place C. imbricata on a long branch, not closely related to any other members of the genus (Fig. 1). C. imbricata differs from all other species of Capnella and Eunephthya by 6–10% at mtMutS, genetic distance values (uncorrected p) that are consistent with average differences among other morphologically distinct soft coral genera (McFadden et al. 2006b), and larger than the average differences typically recorded among congeners (McFadden et al. 2011). Moreover, the leaf clubs and “leaf-capstans” (Verseveldt 1977) found in the polyps and surface of the stalk of C. imbricata (Fig. 2a–c) differ markedly from the sclerite forms found in most other described species of Capnella (Verseveldt 1977). Although molecular data for additional species and genes are needed to support the genetic distinctions among these clades, the morphological differences alone suggest that genus Capnella should be restricted to the type species, C. imbricata, and the other tropical species should be placed in a separate genus. Eunephthya is clearly distinct, morphologically and genetically, from both of these tropical clades.

Capnella species from cold-water regions of Australia are, however, morphologically similar to the South African Eunephthya, with unilaterally spinose spindles in the polyps and radiates in the stalk. Although Verseveldt (1977) did not illustrate tentacle sclerites or mention the presence of transverse spindles in the adaxial surface of the polyp, several Australian species also share these characters with Eunephthya (P. Alderslade, pers. comm.). Molecular data are available for just one cold-water Australian species, but suggest that it falls outside of the South African Eunephthya clade, and is more closely related to the tropical Capnella species (Fig. 1). Additional molecular and morphological work will be necessary to further elucidate the relationship between Eunephthya and the cold-water Australian species currently included within Capnella, but these preliminary molecular data suggest that they are generically distinct.

The northern hemisphere genus Drifa also bears a strong morphological resemblance to both Eunephthya and Capnella, and several previous authors synonymized all three genera as Capnella (Broch 1939; Madsen 1944). While Drifa shares a similar colony growth form and non-retractile polyps with the other two genera, it lacks the unilaterally spinose and leaf spindles characteristic of Eunephthya. Utinomi (1960, 1961) further distinguished Drifa from Capnella based on differences in the density of sclerites in the internal canal walls, but this character appears to vary among species rather than genera (pers. ob.). Material of Drifa suitable for molecular analysis is not currently available.

A chronological list of species originally described as belonging to the genus Eunephthya and their current classification is given here. Historically, a number of other species have been transferred, incorrectly, to Eunephthya from other genera, and discussions of those can be found in Madsen (1944) and Utinomi (1960, 1961):

Eunephthya glomerata Verrill, 1869 (Drifa glomerata see Verrill 1922: 29)

Eunephthya thyrsoidea Verrill, 1869 (Eunephthya thyrsoidea see this publication)

Eunephthya fusca Wright & Studer, 1889 (Chondronephthya fusca see Utinomi 1960: 35) Eunephthya racemosa Studer, 1891 (Pseudodrifa racemosa see Utinomi 1961: 244)

Eunephthya maldivensis Hickson, 1905 (Litophyton maldivensis see Hickson 1908: 173 -176) Eunephthya purpurea Thomson & Henderson, 1905 (Dendronephthya purpurea see Kükenthal, 1907: 379) Eunephthya antarctica Kükenthal, 1906 (Gersemia antarctica, P. Alderslade pers. comm.) Eunephthya japonica Kükenthal, 1906 (Gersemia japonica see Ofwegen 2005: 112)

Eunephthya spiculosa Kükenthal, 1906 (Scleronephthya spiculosa see Ofwegen 2005: 112) Eunephthya hicksoni Gravier, 1913 (Gersemia hicksoni, P. Alderslade pers. comm.)

Eunephthya flavescens Molander, 1915 (Drifa glomerata see Utinomi, 1961: 240)

Eunephthya groenlandica Molander, 1915 (Pseudodrifa groenlandica see Utinomi 1961: 244) Eunephthya rosea Molander, 1915 (Duva multiflora see Utinomi, 1961: 239)

Eunephthya spitzbergensis Molander, 1915 (Duva multiflora see Utinomi, 1961: 239) Eunephthya abrolhosa Thorpe, 1928 (Klyxum abrolhosum, P. Alderslade pers. comm.) Eunephthya brochi Thorpe, 1928 (Klyxum brochi, P. Alderslade pers. comm.)

Eunephthya whitei Thorpe, 1928 (Klyxum whitei, P. Alderslade pers. comm.)

Eunephthya bicolor Utinomi, 1951 (Duva bicolor see Utinomi 1961: 239)

Eunephthya hirotai Utinomi, 1951 (Chromonephthea hirotai see Ofwegen 2005: 111) Eunephthya serratospiculata Utinomi, 1951 (Chromonephthea serratospiculata see Ofwegen 2005: 180) Eunephthya alba Tixier-Durivault, 1961 (genus unknown but not Eunephthya).

In addition to four new species described below, we include in Eunephthya two common South African species, the type species E. thyrsoidea (Verrill, 1865) and E. susanae (Williams, 1988) n. comb. Both of these species are described well elsewhere (Williams 1988, 1992a), but we present new images of the colony form (Fig. 3b, e) and sclerites (Figs. 11–17) of these species here for comparison. In addition to the sclerite forms described and illustrated by Williams (1988, 1992a), it should be noted that both E. susanae n. comb. and E. thyrsoidea also have small spindles in the tentacles (Figs. 11d, 13a, 15d), similar to those of the four new species described below.