Haplosyllis Langerhans, 1879

Lattig, Patricia & Martin, Daniel, 2009, A taxonomic revision of the genus Haplosyllis Langerhans, 1887 (Polychaeta: Syllidae: Syllinae), Zootaxa 2220, pp. 1-40 : 7

Genus Haplosyllis Langerhans, 1879

Haplosyllis Langerhans, 1879: 527

Trypanosyllis (Trypanoseta) Imajima and Hartman, 1964: 129 . Geminosyllis Imajima, 1966: 233 .— Kudenov & Harris, 1995: 71, fig. 1.26.— Lattig et al. 2007: 561 –562. Trypanoseta Aguado et al. 2008: 544

Type species. Syllis spongicola Grube, 1855

Diagnosis. Body cylindrical, reaching large size, from 0.1 mm to 60 mm length. Prostomium with four eyes, sometimes with anterior ocular spots. Three long antennae. Palps robust, triangular, fused at bases. Two pairs of tentacular cirri. Antennae, dorsal cirri and tentacular cirri distinctly moniliform, some species with posterior cirri apparently smooth (but corresponding to a single small article). Ventral cirri digitiform, gradually decreasing in size from anterior to posterior end. Pharynx with one tooth surrounded by 9–12 soft papillae. Trepan, if present, with approximately ten teeth. Chaetae all simple, variable in number, 1–3 or up to 12 per parapodia. Capillary chaetae absent. Schizogamic reproduction by means of a single sexual stolon for each parental individual (scissiparity).

Remarks. Haplosyllis was initially defined as having a single pharyngeal tooth (see Lattig et al. 2007) and the presence of an additional pharyngeal trepan was the main character to distinguish Haplosyllis from Trypanoseta ( Imajima 1966). The dissection and SEM observations of many specimens of H. spongicola (sensu Lattig et al. 2007) revealed in many cases the presence of a trepan ( Fig. 17 A–C). As H. spongicola is the type species of Haplosyllis , the diagnosis of the genus must be modified, and Trypanoseta is no longer considered valid. Besides, Aguado et al. (2007) showed a clear phylogenetic difference between Haplosyllis and Trypanoseta based on molecular data. These authors used two specimens of H. spongicola from the Mediterranean, and other two identified as Haplosyllis sp. and T.. ohma . However, the former were from Australia (where the presence of Haplosyllis spongicola is doubtful), while the latter species was recorded from St. Juan (Washington, U.S.A.), a location distant from Japan, the Type Locality of T. ohma . Taking into account our observations on the morphology of the respective type species, we suggest that the results of Aguado et al. (2007) better reflect the large genetic differences that may occur within Haplosyllis rather than supporting Trypanoseta as a distinct genus. More species need to be analysed genetically in order to obtain reliable results for this genus, both to define intra-generic differences and to define its phylogenetic position within the Syllidae .

Figures

FIGURE 17. SEM micrographs of the pharynx of Haplosyllis spongicola. A—trepan with small teeth arranged in semicircle around pharyngeal tooth; B—complete trepan, small and triangular teeth; C—pharynx covered by a dense ring of cilia, not visible if trepan is present. Arrows pointing to trepan tooth in A and B, the cilia in C. Scale bars: A = 300 Μm; B – C = 100 Μm.