Megalomma fauchaldi Giangrande, Licciano and Gambi, 2007

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 : 31-33

Megalomma fauchaldi Giangrande, Licciano and Gambi, 2007

Figure 11A–G

Megalomma fauchaldi Giangrande, Licciano and Gambi, 2007: 46–47 , Fig. 2 .

Megalomma vesiculosum .— Fauchald, 1977: 62.

Type material examined. [ USNM] 1102753, Acc. No. 2044546, 1 paratype, Belize, lagoon side of Carrie Bow Cay , November 2005, 3 m, in Thalassia .

Additional material examined. [ USNM] 066402, Panama, Galeta Reef , Coll. A. A. Reimer, August 8, 1972, as M. vesiculosum (1 spec.). [ USNM] 066403 , Panama, Galeta Reef , Coll. A. A. Reimer, as M. vesiculosum (2 specs). [ USNM] 57946 , Venezuela, Bahía de Mochima , Cumaná, Coll. R . Edwards , June 22, 1971 (1 spec.). [ ECOSUR] OH-P633 , Yucatan , 1 km off Rio Lagarto beach, 21° 37’ 50’’ N, 88° 9’ 5’’ W, Colls. SISV & LFCP , June 14, 2009 (1 spec). [ ECOSUR] OH-P493 , Quintana Roo , Cabo Catoche, 21° 36’ 18.31’’ N, 87° 6’ 8’’ W, Colls. SISV & LFCP , June 10, 2009 (1 spec). [ ECOSUR] OH-P540 , Quintana Roo , Cabo Catoche, 21° 36’ 18.31’’ N, 87° 6’ 8’’ W, Colls. SISV & LFCP , June 10, 2009 (1 spec).

Diagnosis. Eyes on dorsalmost and lateral 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. Branchial crown longer than thorax with 14 pairs of radioles. Radioles with brown colored bands. Outer surfaces of radioles quadrangular basally, rounded distally. Sub-distal compound eyes present only on dorsalmost and six lateral radioles, spherical, red. Dorsalmost eyes larger than others, radiolar tips short ( Fig. 11D ). Other dorsal eyes smaller than dorsalmost, radiolar tips longer gradually towards lateral and ventral radioles ( Fig. 11E– G ). Dorsal collar margins fused to faecal groove ( Fig. 11A ). Dorsal lappets rounded, longer than lateral collar margins ( Fig. 11A ). Dorsal pockets well developed, prominent, U-shaped ( Fig. 11A ). Ventral lappets triangular, overlapped, as long as ventral shield of collar ( Fig. 11C ). Anterior peristomial ring not exposed dorsally. Lateral collar margins not covering the basal union of radioles ( Fig. 11B ). Dorsal lips with brown, basal spots; triangular with mid-rib. Dorsal pinnular appendages unknown. Ventral lips about a half as long as dorsal lips, broadly rounded with basal brown spots. Ventral sacs present. Caruncle and keel absent. Seven thoracic chaetigers. Tori in chaetigers 2–3 short, occupying a half of the distance between notopodia and ventral shields, not contacting shields ( Fig. 11C ). Inferior thoracic chaetae Type C. Thoracic uncini with main fang surmounted by 7–8 rows of numerous minute teeth, handles 1.5x length of main fang. Companion chaetae with teardrop-shaped membranes. Abdominal neuropodia with slender narrowly hooded chaetae. Abdominal uncini with the main fang surmounted by 7–10 rows of numerous minute teeth. Pygidium unknown. Tube of paratype with calcareous fragments.

Remarks. Megalomma fauchaldi was described from Carry Bow, Belize. It was described as having poorly developed ventral lappets. Paratype and additional samples from Panama present ventral lappets with triangular anterior margins, short and overlapped. The new record provided here is from Venezuela. Fauchald (1977) recorded M. vesiculosum from Galeta Reef, Panama, but reexaminations of these specimens allow us to assign their identity as M. fauchaldi . The distribution of M. vesiculosum seems to be a species with a Northern hemisphere distribution and all records of this species within tropical and subtropical areas must be reviewed, as previously done for the Mediterranean records ( Giangrande & Licciano 2008).

Among species of Megalomma from America, M. fauchaldi resembles M. perkinsi . Both species have dorsal pockets well developed and dorsal lappets present; however, M. fauchaldi has spherical eyes in dorsalmost and lateral radioles, whereas M. perkinsi has oval eyes in most radioles. Megalomma fauchaldi and another nine species share the presence of dorsal lappets, for comparison among these species see remarks on M. acrophthalmos .

Figures

FIGURE 2. Megalomma acrophthalmos (Grube, 1878). A) Thorax, dorsal view; B) thorax, ventral view; C) collar and anterior segments, ventral view; D) peristomium, frontal view; E) thoracic chaetigers; F) dorsal and ventral lips; G) collar and anterior segments, dorsal view; H–I) inferior thoracic chaetae type B; J) dorsalmost radiolar eye; K) eye from a lateral radiole; L) eye from a ventral radiole. A–L) Specimens from Philippines, USNM, 38683. Abbreviations: apr anterior peristomial ring; ca caruncle; d dorsum; dl dorsal lip; dlc dorsal lappets of collar; nl notopodial lobe; v ventrum; vl ventral lobe; vs ventral sacs; vsc ventral shield of collar. Scale bars: A–D, G) 1 mm; E) 0.5 mm; F) 1 mm; H–I) 50 µm; J–L) 0.3 mm.

FIGURE 11. Megalomma fauchaldi Giangrande et al. 2007. A) Thorax, dorsal view; B) same, lateral view; C) same, ventral view; D) dorsalmost radiolar eye; E–G) eyes from lateral radioles. A–G) Specimen from Galeta Reef, Panama, USNM, 066403. Abbreviations: dlc dorsal lappets. Scale bars: A–C) 0.5 mm, D–G) 0.3 mm.