Megalomma claparedei ( 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 : 24

Megalomma claparedei ( Gravier, 1908a)

Figure 5H–P

Branchiomma claparedei Gravier, 1908a: 91–94 , Pl. 7, Figs 265–266.

Megalomma claparèdei .— Johansson, 1927: 132.

Megalomma claparedei .— Hartman, 1959: 550.— Knight-Jones, 1997: 314.— Giangrande and Licciano, 2008: 214–216, Figs 5E–F , 7 .

Type material examined. [ MNHN] 558–559, 2 syntypes, Red Sea, Djibouti, Gulf of Aden, January 1, Coll. Gravier. Syntype 559 incomplete, lacks posterior abdomen and broken in two parts; syntype 558 complete but broken in crown and posterior abdomen.

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

Description. Branchial crown longer than thorax with 12–13 pairs of radioles. Syntype 558 has a purple band located ¾ of branchial crown length, distributed over lateral margins and adjacent pinnules. Outer surfaces of radioles quadrangular at base, rounded distally. Sub-distal compound eyes present in most radioles, except for three ventralmost radioles, all spherical. All radiolar tips very long relative to eyes size ( Fig. 5J ). Dorsal collar margins square, fused to faecal groove ( Fig. 5I ). Dorsal lappets absent. Dorsal pockets present ( Fig. 5I ). Anterior peristomial ring not exposed beyond collar margins. Ventral lappets rounded, not overlapped ( Fig. 5H ), as long as ventral shield of collar length. Lateral margins of collar covering the basal union of radioles. Dorsal lips erect, triangular, with mid-rib. Dorsal pinnular appendages present. Ventral lips short, broadly rounded. Ventral sacs present. Caruncle absent. Low smooth keel, projecting dorsally to the mouth. Body cream colored, slender. Total length 11, 28 mm, maximum width 1.25, 2 mm throughout most of thorax. Seven thoracic chaetigers. Tori in chaetigers 2–3 short, occupying a half of the distance between notopodia and ventral shield margins, not contacting shields ( Fig. 5H ). Notopodial fascicles with superior group of elongate, narrowly hooded chaetae ( Fig. 5L ) and an inferior group of thoracic chaetae Type C ( Fig. 5O ). Thoracic uncini with main fang surmounted by 7–9 rows of numerous minute teeth, handles 2x length of main fang ( Fig. 5P ). Companion chaetae with teardrop-shaped membranes ( Fig. 5N ). Abdominal segments: 32, 90. Abdominal chaetae broadly hooded ( Fig. 5M ). Abdominal uncini with main fang surmounted by 10–12 rows of numerous minute teeth ( Fig. 5K ). Pygidium, gametes and tubes unknown.

Remarks. Megalomma claparedei was collected in a perforation on the bases of the coral Porites by Gravier (1908a), in Djibouti and Gulf of Tadjourah (Red Sea). The species was considered by Giangrande and Licciano (2008) as a Lessepsian migrant in the South Adriatic Sea, where it was found at different depths on hard bottom substrates and also at the base of Posidonia beds where a pre-coralligenous formation is present. According to Giangrande and Licciano (2008), the Mediterranean materials have lateral margins of collar with small notches. This feature was also described by Gravier (1908a). However, syntype 559 examined in this study has the lateral margins of collar entire, whereas syntype 558 has the lateral margins incised but ruptures are heterogeneous, perhaps due to obvious histolysis and manipulation. Also, Giangrande and Licciano (2008) record dorsal lappets, but in syntypes these cannot be considered as such since the margins of collar do not project more than lateral collar margins. Megalomma claparedei , M. acrophthalmos , M. suscipiens and M. nechamae have all radioles with long tips and eyes in most radioles. In M. acrophthalmos eyes in dorsalmost radioles are spiraled (spherical in M. claparedei , M. sp., and M. nechamae ); M. sp., and M. acropththalmos possess a caruncle (absent in M. claparedei and M. nechamae ). Megalomma claparedei lacks dorsal lappets and the lateral collar margins cover the basal union of radioles while in M. nechamae the lateral collar margins do not cover the basal union of radioles and dorsal lappets are present.

Figures

FIGURE 5. Megalomma bioculatum (Ehlers, 1887) and M. claparedei (Gravier, 1908). A, I) Thorax, dorsal views; B–C, H) thorax, ventral views; D, P) thoracic uncini; E–F, N) companion chaetae; G) inferior thoracic chaeta type B; J) dorsalmost radiolar eye; K) abdominal uncinus; L) superior thoracic narrowly hooded chaeta; M) abdominal broadly hooded chaeta; O) inferior thoracic chaeta type B. A–G) Megalomma bioculatum; H–P) Megalomma claparedei. A) Specimen from Florida, MCZ, 47066; B–G) modified from Perkins, 1984; H–I) syntype from Djibouti, MNHN 559; J–P) modified from Gravier, 1908. Abbreviations: apr anterior peristomial ring; dl dorsal lip; dp dorsal pockets; vsc ventral shield of collar. Scale bars: A) 1 mm; H–I) 0.5 mm; B–G, J–P) not scaled.

FIGURE 7. Megalomma coloratum (Chamberlin, 1919). A) Body, lateral view; B) thorax, lateral view; C) glandular ridge on chaetiger 3 as indicated with arrow; D) thorax, ventral view; E) branchial crown and thorax, dorsal view; F) ventralmost radiole; G) dorsalmost radiolar eye; H) eye from 5th dorsal radiole; I) abdominal tori; J–L) pygidiums. A–L) Specimens from Mazatlán, México, ECOSUR. Scale bars: A, E) 10 mm; B–D) 3 mm; F–H) 0.3 mm; I–L) 3 mm.