Amblyosyllis Grube & Ørsted

Fukuda, Marcelo V., Nogueira, João M. M. & Martín, Guillermo San, 2015, Eusyllinae and “ Incertae sedis ” syllids (Annelida: Syllidae) from South America, with a new species from Brazil and a new combination for a Peruvian species, Zootaxa 3936 (4), pp. 507-537 : 508

Genus Amblyosyllis Grube & Ørsted in Grube, 1858

Type species: Amblyosyllis rhombeata Grube & Ørsted in Grube, 1858

Diagnosis. Relatively small-sized body, with few chaetigers and marked intersegmental constrictions; dorsal pigmentation patterns present in some species. Palps free from each other, usually short, ventrally bent beneath prostomium. Prostomium ovate with 3 antennae and 2 pairs of eyes, eyes frequently coalescent on each side of prostomium; anterior eyespots present in some species; nuchal organs as a pair of dorsal projections on posterior part of prostomium, rounded, ovate or digitiform, running posteriorwards for variable extension (epaulettes). Peristomium dorsally short, with 2 pairs of cirri. Antennae, peristomial, dorsal cirri throughout and anal cirri elongate, wrinkled to pseudoarticulated, with conspicuous cirrophores, sometimes with well-defined articles distally; ventral cirri frequently longer than parapodial lobes; antennae and cirri usually with iridescent granules. Compound chaetae as falcigers only, blades bidentate, with short spinulation. Dorsal and ventral simple chaetae rarely present. Aciculae straight, distally pointed, tips frequently protruding from parapodial lobes. Last segment achaetous; pygidium with one pair of long cirri. Pharynx coiled or sinuated, trepan with denticles with variable number of cuspids, central tooth absent; proventricle usually relatively short.

Remarks. Members of Amblyosyllis have the palps ventrally bent, nuchal organs as epaulettes, and convoluted pharynx, features that characterize the subfamily Autolytinae Langerhans, 1879 , however, the genus has recently been placed among the 'Incertae Sedis' ( Aguado et al. 2012). We included Amblyosyllis in the present paper because it has been traditionally allocated within the Eusyllinae , due to the conspicuous ventral cirri and the morphology of falcigers and aciculae, which clearly differ from those of Autolytinae . Also, the reproductive mode likely involves the epigamy ( San Martín & Hutchings 2006), typical of the Eusyllinae , which is confirmed by our finding of one specimen undergoing epigamous maturation process ( Fig. 1 A).

The authorship of this genus has been inaccurately attributed to "Grube, 1857", probably due to confusions with publication dates and different reprints repaginations of the original description. This was recently corrected by Salazar-Vallejo & Eibye-Jacobsen (2012).

Figures

FIGURE 1. Amblyosyllis granosa. (A) anterior and midbody, dorsal view; (B) detail, prostomium, peristomium and chaetiger 1, dorsal view; (C) proventricle and pharynx—arrow pointing to trepan; lpp: left dorsal peristomial cirrus, cirrophore; lps: left dorsal peristomial cirrus, cirrostyle; le: left epaulette; mp: median antenna, antennophore; ms: median antenna, antennostyle; rpp: right dorsal peristomial cirrus, cirrophore; per: peristomium; pro: prostomium; prv: proventricle; re: right epaulette; number refers to the chaetiger. Scale bars: A = 600 Μm; B = 50 Μm; C = 100 Μm.