Megalomma pacifici ( Grube, 1859 )

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 : 44

publication ID

https://doi.org/ 10.11646/zootaxa.2861.1.1

DOI

https://doi.org/10.5281/zenodo.5293054

persistent identifier

https://treatment.plazi.org/id/03CF87C4-2955-1249-FF5C-5FF8FE874080

treatment provided by

Felipe

scientific name

Megalomma pacifici ( Grube, 1859 )
status

 

Megalomma pacifici ( Grube, 1859)

Figures 19A–K View FIGURE 19 , 20A–J View FIGURE 20

Sabella pacifici Grube, 1859: 9 .

Pseudopotamilla panamica Chamberlin, 1919: 268–269 , Pl. 3, Fig. 8 View FIGURE 8 fide Knight-Jones, 1997: 314.

Megalomma pacifici .— Knight-Jones, 1997: 316, Figs 1A–E View FIGURE 1 .

Type material examined. [ ZMUC] POL–1985, holotype incomplete (lacking posterior abdomen) of Sabella pacifici Grube, 1859 , Punta Arenas, Costa Rica. [ MCZ] 72, holotype complete (but broken in two parts) of Pseudopotamilla panamica Chamberlin, 1919 , Panama, Coll. A. Agassiz with the following note in label: “In 1937 species identified by Hartman as M. vesiculosum (Montagu) , reported in the Bull MCZ Vol. LXIII, No 6: 268–69”.

Additional material examined. [Harlan Dean, personal collection] Costa Rica, Bahía Salinas, Coll. Dean, H., on rocky intertidal (1 female). Playa Panamá, Papaguayo, Colls Dean, H. & J. A. Vargas, August 1999, rocky intertidal (1 spec.) . [ ZMUC] POL–1986, Costa Rica, Punta Arenas , Realejo, September 1845, Legit Orsted (1 female) . [ USNM] Acc. 292580, Panama, Shore of Perico Island, Sta. 252–1, lower part of sand beach, soft mud, hard sand/shell, January 25, 1978, Coll. Jones, M. L. (1 spec.) . [ ECOSUR] OH-P0282 , Guerrero , Acapulco, Hornos beach, 16° 51’ 6.4’’ N, 99° 54’ 1’’ W, April 20, 2008, Colls GoogleMaps SISV & LFCP, in sponge (1 spec) . [ ECOSUR] OH-P0284 , Oaxaca , Pueto Angel, Panteon Beach, 15° 39’ 51.7’’ N 96° 29’ 44.8’’ W, April 16, 2008, Colls GoogleMaps SISV & LFCP, in sabellariid reef (1spec) . [ ECOSUR] OH-P0285 , Guerrero , Acapulco, Hornos beach, 16° 51’ 6.4’’ N, 99° 54’ 1’’ W, April 19, 2008, Colls GoogleMaps SISV & LFCP, in oyster Spondylus calcifer (1 spec) . [ ECOSUR] OH-P0287 , Oaxaca , Pueto Angel, Panteon Beach, 15° 39’ 51.7’’ N, 96° 29’ 44.8’’ W, April 16, 2008, Colls GoogleMaps SISV & LFCP, in sabellariid reef (1 spec.) . [ ECOSUR] OH-P0289 , Guerrero , Acapulco, Hornos beach, 16° 51’ 6.4’’ N, 99° 54’ 1’’ W, April 19, 2008, Colls GoogleMaps SISV & LFCP, in oyster Spondylus calcifer (1 spec.) .

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

Description. Branchial crown longer than thorax with 24 radiolar pairs (12–20). Branchial crown with orange bands along entire length (brown in old preserved material). Outer surfaces of radioles quadrangular basally, rounded distally. Sub-distal compound eyes present in most radioles. Dorsalmost pair of radioles with large, spherical and short tips ( Figs 19D View FIGURE 19 , 20J View FIGURE 20 ). Lateral and ventral radioles with spherical eyes decreasing their size towards ventral radioles ( Fig. 19E–F View FIGURE 19 ). Ventralmost radioles with ocular spots and long tips ( Fig. 19G View FIGURE 19 ). Dorsal collar margins rounded posteriorly, fused to faecal groove, forming broad gap ( Figs 20B, H View FIGURE 20 , 19A–B View FIGURE 19 ). Dorsal lappets absent. Dorsal pockets well developed ( Figs 19A–B View FIGURE 19 , 20B, H View FIGURE 20 ). Ventral lappets triangular, not overlapping ( Figs 19C View FIGURE 19 , 20C, F View FIGURE 20 ). Anterior peristomial ring exposed dorsally between dorsal pockets. Lateral margins of collar covering basal union of radioles ( Figs 19B–C View FIGURE 19 ). Dorsal lips erect, triangular about one-quarter length of branchial crown, with midrib and dorsal pinnular appendages. Ventral lips short, broadly rounded. Ventral sacs present. Caruncle and keel absent. Total thorax-abdomen length 34 (19–34) mm, maximum width 5 (2) mm throughout most of thorax. Seven thoracic chaetigers (7). Dorsal thorax dark, except for faecal groove. Lateral margin of ventral thoracic shields brown colored. Ventral shields orange. Thoracic tori longest on chaetigers 2–3. Tori in chaetigers 2–3 occupy the entire distance between notopodia and ventral shield margins ( Figs 19C View FIGURE 19 , 20D–E View FIGURE 20 ), contacting shields. Inferior thoracic chaetae Type C ( Fig. 19H View FIGURE 19 ). Thoracic uncini with crest surmounted by 8–10 rows of numerous minute teeth, handles 2x length of main fang ( Fig. 19I View FIGURE 19 ). Companion chaetae with teardrop-shaped membranes ( Fig. 19I View FIGURE 19 ). Abdomen with 40 chaetigers (42–65). Abdominal chaetae broadly hooded ( Fig. 19K View FIGURE 19 ); chaetae in posterior row longer than those in anterior row. Abdominal uncini with main fang surmounted by 8–10 rows of numerous minute teeth ( Fig. 19J View FIGURE 19 ). Pygidium trilobed with three groups of 4–5 red pygidial eyespots, unequal in size ( Fig. 20I View FIGURE 20 ). Abdominal posterior of holotype regenerating ( Fig. 20G View FIGURE 20 ). Tube attached to large basal stone and composed by shell fragments, echinoderm spines and coralline sand ( Fig. 20A View FIGURE 20 ).

Remarks. Megalomma pacifici , M. circumspectum and M. georgiense n. sp., share the presence of ocular spots in ventralmost radioles. In M. georgiense n. sp., the dorsal collar margins are not fused to faecal groove (fused in M. pacifici and M. circumspectum ). Megalomma pacifici differs from M. circumspectum by having the anterior peristomial ring exposed between dorsal pockets (not exposed in M. circumspectum ) and the thoracic tori longest in chaetigers 2–3 and in contact with ventral shields (same length in all segments and separate from ventral shields in M. circumspectum ).

ZMUC

Zoological Museum, University of Copenhagen

MCZ

Museum of Comparative Zoology

USNM

Smithsonian Institution, National Museum of Natural History

ECOSUR

El Colegio de la Frontera Sur (Mexico)

Kingdom

Animalia

Phylum

Arthropoda

Class

Insecta

Order

Coleoptera

Family

Carabidae

Genus

Megalomma

Loc

Megalomma pacifici ( Grube, 1859 )

Tovar-Hernández, María Ana & Carrera-Parra, Luis F. 2011
2011
Loc

Pseudopotamilla panamica

Chamberlin, R. V. 1919: 269
1919
Loc

Sabella pacifici

Grube, A. E. 1859: 9
1859