Leocratides Ehlers, 1908

Salazar-Vallejo, Sergio I., 2020, Revision of Leocrates Kinberg, 1866 and Leocratides Ehlers, 1908 (Annelida, Errantia, Hesionidae), Zootaxa 4739 (1), pp. 1-114 : 73-74

Leocratides Ehlers, 1908

Leocratides Ehlers, 1908: 63 . Chamberlin 1919: 185; Fauvel 1953b: 107; Pettibone 1970: 229–230; Fauchald 1977: 76; Pleijel, 1998: 109–110, 160.

Type species. Leocratides filamentosus Ehlers, 1908 by monotypy.

Diagnosis. Hesioninae with two lateral antennae, and one median antenna on dorsal prostomial surface. Palps biarticulate, palpophores large, massive, palpostyles smaller, blunt. Eyes dark, black or brown, anterior ones larger than posterior ones, sometimes approaching each other in lateral view. Nuchal organs lobes round, projected posteriorly, parallel to divergent, posterior ciliated bands close to each other. Peristomium with dorsolateral tubercles, often lobate, and ventrolateral ones projected, with a ventral ridge usually with large round papillae. Pharynx with upper jaw double, T-shaped, lower jaw single, fang-shaped; neurochaetal blades bidentate, without guards. Parapodia all sesquiramous. Neurochaetae compound falcigers, blades bidentate, without guards.

Remarks. Leocratides Ehlers, 1908 resembles three other Hesioninae genera by having sesquiramous parapodia: Dalhousiella McIntosh, 1908 , Elisesione Salazar-Vallejo, 2016 , and Hesione Savigny in Lamarck, 1818 . Leocratides differs from these genera because it has biarticulate palps (missing in Hesione , simple in Elisesione , biarticulate in Dalhousiella ), median antenna (missing in Elisesione and Hesione , present in Dalhousiella ), and especially because its pharynx is provided with jaws (missing in the three other genera), being double upper jaws, and single, fang-shaped lower ones.

Further, the nuchal organs lobes, as observed in a syntype of L. filamentosus Ehlers, 1908 , the type species, are depressed, divergent, markedly separated middorsally ( Fig. 44A, D ). There are two other interesting differences in comparison to all other Hesioninae genera, and both might be related to the peristomium. First, there are two complex, dorsolateral tubercles resembling hands by having 3–4 thick digitate lobes as in L. filamentosus Ehlers, 1908 , or 1–2 lobes as in L. ehlersi ( Horst, 1921) . Second, midventrally there is a continuous ridge with 8–10 large, thick, round papillae.

Figures

FIGURE 44. Leocratides filamentosus Ehlers, 1908, syntypes (ZMB 4431). A. Smallest syntype, anterior region, dorsal view. B. Anterior end, oblique frontal view. C. Chaetiger 10, left parapodium, anterior view (inset: neuracicular lobe). D. Largest syntype, anterior region, dorsal view. E. Anterior end, oblique frontal view. F. Chaetiger 10, right parapodium, anterior view (inset: neuracicular lobe). Scale bars: A: 1.5 mm; B: 1 mm; C: 0.4 mm; D: 0.9 mm; E: 1.2 mm; F: 0.6 mm.