Megalomma pacifici
Creators: name: Tovar-Hernández, María Ana
name: Carrera-Parra, Luis F.
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Carabidae
Megalomma
Megalomma pacifici

description: <i>Megalomma pacifici</i> (Grube, 1859) Figures 19A–K, 20A–J <i>Sabella pacifici</i> Grube, 1859: 9. <i>Pseudopotamilla panamica</i> Chamberlin, 1919: 268–269, Pl. 3, Fig. 8 <i>fide</i> Knight-Jones, 1997: 314. <i>Megalomma pacifici</i>.— Knight-Jones, 1997: 316, Figs 1A–E. <b>Type material examined. [ZMUC]</b> POL–1985, holotype incomplete (lacking posterior abdomen) of <i>Sabella pacifici</i> Grube, 1859, Punta Arenas, Costa Rica. <b>[MCZ]</b> 72, holotype complete (but broken in two parts) of <i>Pseudopotamilla panamica</i> Chamberlin, 1919, Panama, Coll. A. Agassiz with the following note in label: “In 1937 species identified by Hartman as <i>M. vesiculosum</i> (Montagu), reported in the Bull MCZ Vol. LXIII, No 6: 268–69”. <b>Additional material examined. [Harlan Dean,</b> personal collection <b>]</b> Costa Rica, Bahía Salinas, Coll. Dean, H., on rocky intertidal (1 female). Playa Panamá, Papaguayo, Colls Dean, H. &amp; J. A. Vargas, August 1999, rocky intertidal (1 spec.). <b>[ZMUC]</b> POL–1986, Costa Rica, Punta Arenas, Realejo, September 1845, Legit Orsted (1 female). <b>[USNM]</b> 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.). <b>[ECOSUR]</b> OH-P0282, Guerrero, Acapulco, Hornos beach, 16° 51’ 6.4’’ N, 99° 54’ 1’’ W, April 20, 2008, Colls SISV &amp; LFCP, in sponge (1 spec). <b>[ECOSUR]</b> OH-P0284, Oaxaca, Pueto Angel, Panteon Beach, 15° 39’ 51.7’’ N 96° 29’ 44.8’’ W, April 16, 2008, Colls SISV &amp; LFCP, in sabellariid reef (1spec). <b>[ECOSUR]</b> OH-P0285, Guerrero, Acapulco, Hornos beach, 16° 51’ 6.4’’ N, 99° 54’ 1’’ W, April 19, 2008, Colls SISV &amp; LFCP, in oyster <i>Spondylus calcifer</i> (1 spec). <b>[ECOSUR]</b> OH-P0287, Oaxaca, Pueto Angel, Panteon Beach, 15° 39’ 51.7’’ N, 96° 29’ 44.8’’ W, April 16, 2008, Colls SISV &amp; LFCP, in sabellariid reef (1 spec.). <b>[ECOSUR]</b> OH-P0289, Guerrero, Acapulco, Hornos beach, 16° 51’ 6.4’’ N, 99° 54’ 1’’ W, April 19, 2008, Colls SISV &amp; LFCP, in oyster <i>Spondylus calcifer</i> (1 spec.). <b>Diagnosis.</b> 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. <b>Description.</b> 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, 20J). Lateral and ventral radioles with spherical eyes decreasing their size towards ventral radioles (Fig. 19E–F). Ventralmost radioles with ocular spots and long tips (Fig. 19G). Dorsal collar margins rounded posteriorly, fused to faecal groove, forming broad gap (Figs 20B, H, 19A–B). Dorsal lappets absent. Dorsal pockets well developed (Figs 19A–B, 20B, H). Ventral lappets triangular, not overlapping (Figs 19C, 20C, F). Anterior peristomial ring exposed dorsally between dorsal pockets. Lateral margins of collar covering basal union of radioles (Figs 19B–C). 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, 20D–E), contacting shields. Inferior thoracic chaetae Type C (Fig. 19H). Thoracic uncini with crest surmounted by 8–10 rows of numerous minute teeth, handles 2x length of main fang (Fig. 19I). Companion chaetae with teardrop-shaped membranes (Fig. 19I). Abdomen with 40 chaetigers (42–65). Abdominal chaetae broadly hooded (Fig. 19K); 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). Pygidium trilobed with three groups of 4–5 red pygidial eyespots, unequal in size (Fig. 20I). Abdominal posterior of holotype regenerating (Fig. 20G). Tube attached to large basal stone and composed by shell fragments, echinoderm spines and coralline sand (Fig. 20A). <b>Remarks.</b> <i>Megalomma pacifici</i>, <i>M. circumspectum</i> and <i>M</i>. <i>georgiense</i> <b>n. sp.</b>, share the presence of ocular spots in ventralmost radioles. In <i>M</i>. <i>georgiense</i> <b>n. sp.</b>, the dorsal collar margins are not fused to faecal groove (fused in <i>M. pacifici</i> and <i>M. circumspectum</i>). <i>Megalomma pacifici</i> differs from <i>M. circumspectum</i> by having the anterior peristomial ring exposed between dorsal pockets (not exposed in <i>M. circumspectum</i>) 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 <i>M. circumspectum</i>).
description: Published as part of <i>Tovar-Hernández, María Ana &amp; Carrera-Parra, Luis F., 2011, Megalomma Johansson, 1925 (Polychaeta: Sabellidae) from America and other world-wide localities, and phylogenetic relationships within the genus 2861, pp. 1-71 in Zootaxa 2861 (1)</i> on page 44, DOI: 10.11646/zootaxa.2861.1.1, http://zenodo.org/record/5286352
description: {"references": ["Grube, A. E. (1859) Annulata Oerstediana. Enumeratio Annulatorum, quae in itinere per Indiam occidentalem et American centralem annis 1845 - 1848 suscepto legit cl. A. S. Oersted, adyectis speciebus nonnullis a cl. H. Kroyer in itinere ad Americam meridionalem collectis, Pt. 3. Videnskabelige Meddelelser fra Dansk Naturhistorisk Forening, 1859 (1858), 105 - 120.", "Chamberlin, R. V. (1919) New polychaetous annelids from Laguna Beach, California. Journal of Entomology and Zoology, Pomona College, 11, 1 - 23."]}