Megalomma mushaense Gravier 1908a

Tovar-Hernández, María Ana & Carrera-Parra, Luis F., 2011, Megalomma Johansson, 1925 (Polychaeta: Sabellidae) from America and other world-wide localities, and phylogenetic relationships within the genus 2861, Zootaxa 2861 (1), pp. 1-71 : 42

Megalomma mushaense Gravier 1908a

Figure 18K–R

Branchiomma mushaensis Gravier, 1908a: 94–97 , Pl. 7, Figs 267–270.

Megalomma mushaense .— Knight-Jones, 1997: 314, Fig. 4N .

Type material examined. [ MNHN] 555, holotype, Branchiomma mushaensis Gravier, 1908a , Red Sea, Djibouti, Gulf of Aden, Gulf of Tadjoura, in Pocillopora , female with oocytes in medium abdomen, partially dry.

Diagnosis. Eyes in most radioles (spherical); dorsal margins of collar fused to faecal groove; dorsal lappets and dorsal pockets present; thoracic chaetae Type C; abdominal chaetae narrowly hooded.

Description. Radiolar eyes in most radioles, spherical. Dorsalmost radioles with long tips decreasing gradually towards ventral radioles. Dorsal collar margins fused to faecal groove ( Fig. 18K ). Dorsal lappets present, rounded, not longer than lateral collar margins. Dorsal pockets present ( Fig. 18K ). Ventral lappets with rounded anterior margins, not overlapped. Anterior peristomial ring not exposed dorsally. Lateral collar margins not covering basal union of radioles. Dorsal lips and dorsal pinnular appendages unknown. Ventral lips unknown. Ventral sacs present. Caruncle absent. Keel unknown. Thoracic tori longest on chaetiger 2. Notopodial fascicles with superior group of elongate, narrowly hooded chaetae ( Fig. 18L–M ); and an inferior group of chaetae Type C ( Fig. 18O ). Thoracic uncini with crest surmounted by 7–9 rows of numerous minute teeth, handles 1.5x length of main fang ( Fig. 18Q ). Companion chaetae with teardrop-shaped membranes ( Fig. 18N ). Abdominal chaetae narrowly hooded ( Fig. 18R ). Abdominal uncini with main fang surmounted by 8–10 rows of numerous minute teeth ( Fig. 18P ).

Remarks. Megalomma mushaense is unique by having dorsalmost radioles with long tips decreasing gradually towards ventral radioles and dorsal lappets rounded, shorter than lateral collar margins. Dorsal lappets in M. phyllisae , M. quadrioculatum and M. vesiculosum are short, equal in length to lateral collar margins. In M. acrophthalmos , M. fauchaldi , M. lanigera , M. perkinsi , M. sp., and M. nechamae dorsal lappets are also rounded but longer than lateral collar margins.

Figures

FIGURE 4. Megalomma circumspectum (Moore, 1923). A) Thorax, dorsal view; B) same, ventral view; C) same, lateral view; D) ventral sacs as indicated with arrows, branchial crown removed; E) posterior end; F) eyes from dorsal radioles; G) dorsalmost radiolar eye; H) eye from 2nd dorsal radiole; I) eye from a lateral radiole; J) ventralmost ocular spot. A–J) Specimens from La Paz, México, ECOSUR. Scale bars: A–C, E) 1 mm; D) 0.5 mm; F) 2 mm; G–J) 0.3 mm.

FIGURE 18. Selected structures of Megalomma species. A–B) Thorax, ventral views; C) thorax, lateral view; D–F, K, T) thorax, dorsal views; G) dorsal lips; H–J) dorsalmost radiolar eyes; L–M) superior narrowly hooded thoracic chaetae; N) companion chaeta; O) inferior thoracic chaetae type C; P) abdominal uncinus; Q) thoracic uncinus; R) narrowly hooded abdominal chaeta. A, D, G–H) Megalomma modestum (de Quatrefages, 1866); B, F, J) Potamilla anophthalma Hartmann-Schröder, 1960; C, E, I) Potamilla clara Chamberlin, 1919; K–R) Megalomma mushaense (Gravier, 1908a). A, D, G–H) Syntype from Perú, MNHN, 163; B, F, J) holotype from Perú, ZMH, 15435; C, E, I) holotype from California, MCZ, 2171; K–R) modified from Gravier, 1908a. Abbreviation: dl dorsal lip. Scale bars: A–B, D–F: 1 mm; C: 2 mm; G–J: 0.25 mm; K–R: not scaled.