Clavodorum Hartman & Fauchald, 1971

Capa, Maria, Nygren, Arne, Parapar, Julio, Bakken, Torkild, Meissner, Karin & Moreira, Juan, 2019, Systematic re-structure and new species of Sphaerodoridae (Annelida) after morphological revision and molecular phylogenetic analyses of the North East Atlantic fauna, ZooKeys 845, pp. 1-97 : 9-11

Clavodorum Hartman & Fauchald, 1971

Sphaerodoridium Lützen, 1961: 415 (in part); Fauchald 1974: 270; Capa et al. 2014: 15.

Clavodorum Hartman & Fauchald, 1971: 63; Fauchald 1974: 262; Bakken 2002: 198; Capa et al. 2014: 15.

Type species.

Clavodorum atlanticum Hartman & Fauchald, 1971.

Diagnosis.

Body generally short and ellipsoid. Head appendages smooth without spurs or basal papillae. Median antenna shorter, equal, or longer than lateral antennae; antenniform papillae absent. Dorsal macrotubercles stalked, without terminal papilla, arranged in up to six longitudinal rows, one transverse row per segment; smaller tubercles, similarly stalked, may form irregular rows on ventrum. Microtubercles (small tubercles with collar and terminal papilla) absent. Stout hooks in the first chaetiger absent. Parapodia with large ventral cirri. All chaetae compound.

Remarks.

The relative length of the median antenna with respect to the lateral ones was the single reported morphological feature separating the traditional Clavodorum (with a median antenna longer than the lateral, or similar in length) and Sphaerodoridium (with a shorter median antenna), the two genera considered to bear stalked dorsal macrotubercles prior to the present study (e.g., Hartman and Fauchald 1971, Fauchald 1974). However, there has been some debate if this character alone was enough to split species in these two genera ( Hartmann-Schröder and Rosenfeldt 1990, Borowski 1994, Capa et al. 2016a).

After analyses of molecular data performed in this study (Fig. 1) species with sessile macrotubercles (e.g., Sphaerodoropsis balticum ) were recovered nested within those with stalked macrotubercles (e.g., Sphaerodoridium minutum and Sphaerodoridium guerritai ), requiring nomenclatural changes. Moreover, species with apparently shorter or longer median antenna are mixed in two different clades.

There seems to be some synapomorphies, related to the number of longitudinal rows of dorsal macrotubercles (Clade 3 and 4 in Fig. 1), characterizing these two clusters. In one clade, all the species bear up to six longitudinal rows of stalked macrotubercles (including the type species of Clavodorum , Clavodorum atlanticum ), and in the other species bear more than six longitudinal rows of macrotubercles, regardless if they are sessile or stalked (including the type species of Sphaerodoridium , Sphaerodoridium claparedii ). This pattern should be corroborated after including additional taxa in analyses, but it also requires some changes in the traditional classification.

Diagnostic features characterising Clavodorum , as traditionally understood, such as presence of postchaetal lobes ( Fauchald 1974, Bakken 2002) or presence of nephridiopores in all chaetigers except for the first and the last three or four ( Hartman and Fauchald 1971, Bakken 2002), have been omitted from the diagnosis as it has not been verified in some of the specimens examined nor are mentioned in the original description.

The species included in Clavodorum after this study are:

Clavodorum adriaticum Katzmann, 1973

Type locality: Zlarin, Adriatic Sea, 20-60 m.

Clavodorum antarcticum Hartmann-Schröder & Rosenfeldt, 1990

Type locality: Elephant Island, north of Antarctic Peninsula, 262 m.

Clavodorum atlanticum Hartman & Fauchald, 1971

Type locality: northwest of Bermuda in 4700-3800 m.

Clavodorum clavatum Fauchald, 1972

Type locality: Off El Segundo, California, 18-45 m.

Clavodorum fauchaldi Desbruyères, 1980

Type locality: Banc Le Danois, Bay of Biscay, 1913 m.

Clavodorum fusum (Hartman, 1967)

Type locality: Antarctic Peninsula, 128-165 m.

Clavodorum kristiani ( Hartmann-Schröder, 1993), comb. n., nom. n.

Type locality: North Sea, off Scotland, 172 m.

Clavodorum longipes Fauchald, 1974

Type locality: Off Mozambique, 5119 m.

Clavodorum lutzeni (Kudenov, 1987), comb. n.

Type locality: Off Florida, Gulf of Mexico, 37 m.

Clavodorum mexicanum Kudenov, 1987

Type locality: Off Florida, Gulf of Mexico, 48 m.