Megalomma fauchaldi, Giangrande, Adriana, Licciano, Margherita & Gambi, Maria Cristina, 2007

Giangrande, Adriana, Licciano, Margherita & Gambi, Maria Cristina, 2007, A collection of Sabellidae (Polychaeta) from Carrie Bow Cay (Belize, western Caribbean Sea) with the description of two new species, Zootaxa 1650, pp. 41-53 : 46-47

publication ID

https://doi.org/ 10.5281/zenodo.179763

DOI

https://doi.org/10.5281/zenodo.3509397

persistent identifier

https://treatment.plazi.org/id/038387F5-FFEF-FF8C-FF7F-B31D597DFBAB

treatment provided by

Plazi

scientific name

Megalomma fauchaldi
status

sp. nov.

Megalomma fauchaldi View in CoL sp. nov.

Figure 2 View FIGURE 2

Material examined. Type material: Holotype, on Thalassia at 3 m, on lagoon side of CBC, collected in November 2005, MNCN 16.01/11018 (sample CBC-KF 1012). Paratypes, one specimen from the same locality USNM 1102753; two specimens from the same locality PCZL.

Description. Holotype specimen complete with 8 thoracic and 58 abdominal chaetigers. Body length 20 mm, width 3 mm. Crown length 7 mm; 14–15 pairs of radioles in each lobe with three brown bands. Subterminal compound eyes on seven pairs of radioles. Dorsalmost radioles bearing larger eyes and small tip beyond the eye spot ( Fig. 2 View FIGURE 2 D). The others with smaller eyes and longer tips ( Fig. 2 View FIGURE 2 E). Dorsal lips long with broad base, with brown pigment ( Fig. 2 View FIGURE 2 A), radiolar appendage present, long, 1/4 of length of radioles. Ventral lips with parallel lamellae. Dorsal margin of collar fused to faecal groove and forming two very deep pockets, clearly visible. Base of collar dorsally completely enveloping first chaetiger and extending to second chaetiger ( Fig. 2 View FIGURE 2 A, B). Collar slightly higher ventrally with poorly developed lappets ( Fig. 2 View FIGURE 2 C). Ventral shield of first chaetiger quadrangular, following shields rectangular ( Fig. 2 View FIGURE 2 C). Chaetiger 3 with four superior thoracic notochaetae elongate narrowly hooded. Inferior thoracic notochaetae broadly-hooded, resembling paleate chaetae and arranged in two rows, 10 present in chaetiger 3 ( Fig. 2 View FIGURE 2 F). Thoracic neuropodia widely separated from ventral shield ( Fig. 2 View FIGURE 2 C), neurochaetae avicular with well developed breast ( Fig. 2 View FIGURE 2 G), up to 20 uncini on chaetiger 1, and 14 on last thoracic neuropodia. Companion chaetae with roughly symmetrical tips, with teardropshaped membrane ( Fig. 2 View FIGURE 2 H). Abdominal neurochaetae arranged in two rows, anterior row with elongate, narrowly hooded chaetae and modified, elongate, narrowly-hooded chaetae in posterior row, about 7 per row. Abdominal uncini avicular with manubrium shorter than present on thoracic uncini, about 14 present per torus on mid abdominal segments. Tube encrusted with shell and sand.

Remarks. The number of chaetae and neurochaetal uncini is variable along the body of all material examined. The number of superior thoracic chaetae ranges from 4 to 7, the number of inferior thoracic chaetae from 3 to 10, the number of thoracic uncini from 14 to 20, and the number of abdominal chaetae from 5 to 7, in each row.

Megalomma View in CoL species are usually placed into 5 artificial groups on the basis of whether the mid-dorsal collar margins are fused to the faecal groove or are unattached, whether the dorso-lateral collar margin forms pockets or not, and the distribution and abundance of eyes on the radioles ( Knight-Jones, 1997). Although artificial, these groups have been useful for species comparison ( Nishi, 1998; Fitzhugh, 2002, 2003). The newly described species belongs to the group “1A”, which is defined by the dorsal margin of the collar being fused to the faecal grove, the presence of dorso-lateral pockets, and the occurrence of eyes on most radioles. Among the sabellid species previously listed from the Carribean (Tovar - Hernández and Salazar-Vallejo, 2006) including M. vesiculosum (Montagu, 1815) View in CoL , M. lobiferum (Ehlers, 1887) View in CoL , M. pacificum Johansson, 1927 , M. heterops Perkins, 1984 View in CoL , M. bioculatum (Ehlers, 1887) View in CoL , M. pigmentum (Reish, 1963) View in CoL , and M. perkinsi View in CoL Tovar- Hernández and Salazar-Vallejo, 2006, only M. vesiculosum View in CoL , M. lobiferum View in CoL and M. pacificum belong to this group. Megalomma fauchaldi View in CoL n. sp., can be distinguished from M. lobiferum View in CoL by lacking the “caruncle”, a distinctive feature which is present also in M. pigmentum View in CoL , and in other two species from the Caribbean area, previously described as M. pigmentum View in CoL by Perkins (1984), and Megalomma View in CoL sp. 2 (Tovar-Hernández and Salazar- Vallejo, 2006), but probably belonging to different species for the moment indicated as Megalomma View in CoL sp. 1 and Megalomma View in CoL sp 2. Megalomma fauchaldi View in CoL n. sp., differs from M. pacificum , and M. vesiculosum View in CoL , whose presence within the Caribbean region needs confirmation, especially with regards to the presence of the broadlyhooded inferior thoracic chaetae. This is particularly relevant for records of M. vesiculosum View in CoL from the Caribbean, following the recent revision of Mediterranean species which limits the distribution of this taxon to high latitudes (Giangrande and Licciano, in press). Finally, the collar features of M. fauchaldi View in CoL n. sp. clearly distinguish this taxon from all the other worldwide distributed species belonging to group “1A”, as it has chaetae of similar shape to those present in M. fauchaldi View in CoL n. sp., M. claparedei (Gravier, 1908) View in CoL from the Red Sea, M. circumspectum (Moore, 1923) View in CoL from California, M. multioculatum Fitzhugh, 2002 View in CoL from Thailand and M. suspiciens (Ehlers, 1904) View in CoL from New Zealand. The shape of the collar of M. fauchaldi View in CoL , with the ventral pockets extending to the second chaetiger, appears unique within Megalomma View in CoL . Among the species of the group “1A”, a similar feature is also present in M circumspectum (Moore, 1923) View in CoL and M. lanigera (Grube, 1846) View in CoL in which, however, the pocket base does not reach the second chaetiger.

Type locality: Carrie Bow, Belize.

Etymology: This species is named in honour of Kristian Fauchald as a tribute of his major contribution to polychaete systematics, his kindness and long friendship with us, and facilitating our visit the CBC.

MNCN

Museo Nacional de Ciencias Naturales

USNM

Smithsonian Institution, National Museum of Natural History

Kingdom

Animalia

Phylum

Annelida

Class

Polychaeta

Order

Sabellida

Family

Sabellidae

Genus

Megalomma

Loc

Megalomma fauchaldi

Giangrande, Adriana, Licciano, Margherita & Gambi, Maria Cristina 2007
2007
Loc

M. multioculatum

Fitzhugh 2002
2002
Loc

M. heterops

Perkins 1984
1984
Loc

M. pigmentum

Reish 1963
1963
Loc

M. pacificum

Johansson 1927
1927
Loc

M. circumspectum

Moore 1923
1923
Loc

M circumspectum

Moore 1923
1923
Loc

M. claparedei

Gravier 1908
1908
Loc

M. suspiciens

Ehlers 1904
1904
Loc

lobiferum

Ehlers 1887
1887
Loc

M. bioculatum

Ehlers 1887
1887
Loc

M. lanigera

Grube 1846
1846
Loc

M. vesiculosum

Montagu 1815
1815
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