Megalomma circumspectum ( Moore, 1923 )

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: 19-24

publication ID

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

persistent identifier

http://treatment.plazi.org/id/03CF87C4-296C-1275-FF5C-5C70FCD84515

treatment provided by

Felipe

scientific name

Megalomma circumspectum ( Moore, 1923 )
status

 

Megalomma circumspectum ( Moore, 1923)  

Figures 4A–J View FIGURE 4 , 6A–V View FIGURE 6 , 28A, G View FIGURE 28 , 29A View FIGURE 29

Branchiomma circumspectum Moore, 1923: 239–241   , Pl. 18, Figs 41–42.

Megalomma circumspectum   .— Hartman, 1959: 550.— Hartman, 1961: 43.— Hartman, 1969: 707, Figs 1–6 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 .— Rioja, 1962: 213–216, Figs 145–148.— Fauchald, 1972: 33.— Perkins, 1984: 363.— Knight-Jones, 1997: 314.— Hernández-Alcántara and Solís-Weiss, 1999: 29.

Type material examined. [ USNM] 17021, Acc. No. 60417, holotype, off Brockway Pt. Santa Rosa, California, Albatross , April 15, 1904, Sta. 4431, 74.98 m   .

Additional material examined. [ CSD – MBL] California, USA, Sta. A4, 4, 32º 41’ 4’’ N, 117º 18’ 25” W, October 23, 1990, 80 m, Coll. DN (1 spec.). Sta. A4, 4, 32º 41’ 4’’ N, 117º 18’ 25” W, October 7, 1991, 80 m (1 spec.). [ ECOSUR] GoogleMaps   Baja California Norte , México, Ensenada, Punta Morro, Colls SISV, NEG & ASG   , March 19, 2004, in mussels (4 specs). Playa las Rosas , July 30, 1987, Coll. SISV (4 specs)   . Baja California, May , 07, 1981, Coll. SISV (4 specs)   ; June 04, 1982, Coll. SISV (1 spec.)   . Baja California Sur, México, Bahía la Paz , Presidente, Coll. SISV & JALG   , August 23, 1987 (1 female); October 04, 1987 (5 specs); October 10, 1987 (3 specs); La Paz, Coll. AASD   , March 02, 2004, 1 m (3 specs); Enfermería, Colls SISV & JALG   , June 12, 1987 (1 spec.); June 15, 1987 (12 specs). Bahía de los Ángeles, Playa Municipal, Coll. SISV   , November 11, 1985 (4 specs); Moradas, Coll. SISV   , May 25, 1986 (1 spec.); March 17, 1985, Coll. Carmina (2 specs). Bahía Concepción , Tasajera, Coll. SISV   , October 22, 1985 (8 specs). Nayarit, México, Aticana , Colls PSS & BYR   , November 25, 2004 (4 specs, 1 female, 1 male). La Manzanilla, Colls PSS & BYR   , November 29, 2004 (3 females). [ LACM – AHF]   California, USA, Arroyo Hondo , St. 315ARRHON, SubID 4384, 34.47191º N, 120.14616º W, Coll. Marine Pollution Studies Lab / Moss Landing Marine Laboratories, Invasive Species Survey, October 08, 2007, subtidal rocky habitat, 7 m (1 spec.). Velero III GoogleMaps   , 003489, Sta. 1295–41, 1.8 km SE of Smugglers Cove, Santa Cruz Island   , 34º 00’ 35’’ N, 119º 31’ 30’’ W, April 12, 1941, coralline, sand, pebbles, 38.2 m (1 spec.). Velero IV, Sta. 2315–53, Cruise 118, 4.18 km from Los Angeles Breakwater Lighthouse, 33º 40’ 4’’ N, 118º 16’ 2’’ W, May 19, 1953, sandy mud-shells fragments (1 spec.). Gulf of California, México, Velero III, F3279   , Sta. 1105–40, West coast, 7.4 km SE of Marcial Point, 25º 28’ 28’’ N, 110º 58’ 00’’ W, February 13, 1940, 205.66 m, green mud (4 specs). Velero IV, F3299, Sta. 1711– 49, 53 km 191º T GoogleMaps   from Abre Ojos Light , S of Punta Abre Ojos, 26º 15’ 56’’ N, 113º 40’ 30’’ W, March 03, 1949, 94.6 m, brachiopods and alcyonarians, coarse sand, broken shell and shale (3 specs). Velero IV, F3269, Sta. 1922–49, Cruise 35, 5.04 km 352º T GoogleMaps   from S Bluff, 28º 55’ 23’’ N, 118º 13’ 21’’ W, December 19, 1949, 72.8 m, sandy bottom (2 specs). Velero IV, Cruise 63, F3350, Sta. 2026–51, S. Bay, Isla Cedros GoogleMaps   , 28º 5’ 00’’ N, 115º 19’ 45’’ W, April 19, 1951, 34.5 m, mud sand and bottom (1 spec.). Velero IV, F3320, Sta. 1703–49, S Bay, Isla Cedros GoogleMaps   , 28º 4’ 25’’ N, 115º 17’ 58’’ W, Mach 05, 1949, 29.12 m, sand and mud (2 specs). N 15198 View Materials , Sta. 116, Gulf of California , Knudsen , July 1955 (1 spec.). F3341, Sta. 634.37, San Gabriel Bay, Espiritu Santo Island, March 06, 1937, shore (2 specs). F3376, Sta. 510–36, Cove S of Ballena Bay, Espiritu Santo Island, February 22, 1936, shore (2 specs). F3379   , N 15202 View Materials , n 1295, San Gabriel Bay , Espiritu Santo Island, Coll. E. F. Ricketts, April 12, 1940, in sand (16 specs). Velero III, F3370   , Sta. 1079–40, Point island, Angel de la Guardia Island   , 29º 02’ 35’’ N, 113º 07’ 40’’ W, February 4, 1940, shore, rock (3 specs). Velero IV, F3301, Sta. 1919–49, Cruise 35, Melpomene Cove, Guadalupe Island GoogleMaps   , 28º 52’ 15’’ N, 118º 16’ 56’’, 66.52 m, December 19, 1949, sandy (1 spec.). F3362, N 15195 View Materials , n 10466, P 196–60, off coast Hermosillo , 28º 45.8’ N, 112º 04.0’ W, Coll. Parker, March 27, 1960, 23.4 m, shelly sand (1 spec.). Velero III GoogleMaps   , 003435, Sta. 1412–41, 1.5 mi S of Crook Point, San Miguel Island, 33º 59’ 00’’ N, 120º 22’ 18’’ W, September 16, 1941, 78.26 m, sand, shell (3 specs). Velero III, F3252 GoogleMaps   , Sta. 1045–40, S. Shore of Tiburon Island   , 28º 45’ 35’’ N, 112º 17’ 45’’ W, January 25, 1940, shore (2 specs). Sta. 473, Punta Choya, Puerto Peñasco, Sonora, Coll. S.A. Glassell, May 09, 1941, intertidal (2 specs). F3383, N 15205 View Materials , n. 714, Punta Choya , Puerto Peñasco, Sonora, Coll. S.A. Glassell, May 14, 1941, sand and shell incrustated tubes at low tidal zone (2 specs). F3314, V   1, 15172, Puerto Peñasco , Gallardo’s (1 spec.). Sta. 1292, Ca 3, Coronado Islands , Colls Steinbeck & Ricketts, March 27, 1940 (2 specs). [ LACSD – MBL]   California, USA, Sta. 0191–2D   , 33° 44’ 34’’ N, 118° 25’ 13’’ W, January 16, 1991, 31 m (1 spec.). Sta. 0196–1D, 33° 46’ 01’’ N, 118° 26’ 02’’ W, January 24, 1996, 31 m (1 spec.). Sta. 0700–1D, 33° 46’ 01’’ N, 118° 26’ 02’’ W, July 12, 2000, 31 m, 13.5°C, dark olive silty sand (1 spec.). [ USNM] GoogleMaps   California, USA, 41461, La Jolla   , California, January 19, 1938 (1 spec.). Gulf of   California, México, 41462, Isla Cerralvo , Gulf of California, October 16, 1956, Coll. Klawe (1 spec.)   .

Diagnosis. Eyes in most radioles (spherical); ocular spots in ventralmost radioles; dorsal margins of collar fused to faecal groove; keel present; thoracic chaetae Type C; companion chaetae with teardrop and sickle-shaped membranes.

Description. Branchial crown longer than thorax with 13 pairs of radioles (13–29). Radioles with four purple bands distributed over outer and lateral radiole margins and adjacent pinnules, each band occupies a space of 3–4 pairs of pinnules. Outer surfaces of radioles quadrangular along the entire length. Sub-distal compound eyes present in most radioles ( Fig. 4F View FIGURE 4 ). Dorsalmost pair of radioles longer than others, rigid, rachis notably thick in lateral view ( Fig. 6H View FIGURE 6 ), eyes distinctly larger, spherical, radiolar tips very short ( Fig. 4G View FIGURE 4 ) with a thick epithelium near the compound eye ( Fig. 6I View FIGURE 6 ). Second to lateral and ventral pairs of radioles with spherical eyes distinctly smaller than dorsalmost ones ( Figs 4H–I View FIGURE 4 , 6J–L View FIGURE 6 ). Radiolar tips longer gradually towards ventral radioles ( Fig. 4H–J View FIGURE 4 ) with narrow rachis in lateral view ( Fig. 6M View FIGURE 6 ). Ventralmost radioles with ocular spots ( Fig. 4J View FIGURE 4 ). Dorsal collar margins rounded posteriorly, fused to faecal groove ( Figs 4A, D View FIGURE 4 , 6Q View FIGURE 6 ). Dorsal lappets absent. Dorsal pockets present ( Figs 4A View FIGURE 4 , 6C View FIGURE 6 ). Epithelium of dorsal pockets translucent and narrow, as a membrane, it is easily broken longitudinally ( Fig. 6E View FIGURE 6 ). Triangular ventral lappets, not overlapped, as long as ventral shield of collar ( Fig. 4B, D View FIGURE 4 ) and vascularized by a dense net of blood vessels. Anterior peristomial ring not exposed beyond collar margins. Lateral collar margins covering basal union of radioles ( Figs 4C View FIGURE 4 , 6A, D View FIGURE 6 ). Dorsal lips purple, triangular, very long (about 1/2 of branchial crown length) with mid-rib. Dorsal pinnular appendages present. Ventral lips about one-quarter as long as dorsal lips, broadly rounded. Ventral sacs present ( Fig. 4D View FIGURE 4 ), in some specimens sacs full of sand. Caruncle absent. Low smooth keel, projecting dorsally to the mouth. Body cream colored, depressed. Total thorax-abdomen length 27 mm (10–94), maximum width 2 mm throughout most of thorax (2–4). Seven thoracic chaetigers. Tori in chaetigers 2–3 short, occupying a half of the distance between notopodia and ventral shield margins, not contacting shields ( Figs 4B View FIGURE 4 , 6B View FIGURE 6 ). Notopodial fascicles with a superior group of elongate, narrowly hooded chaetae ( Fig. 6R–S View FIGURE 6 ); inferior group of chaetae Type C ( Figs 6T–U View FIGURE 6 , 28A View FIGURE 28 ). Thoracic uncini with main fang surmounted by 7–9 rows of numerous minute teeth ( Fig. 6P View FIGURE 6 ), handles 1.5x length of main fang; slightly longer than companion chaetal shaft ( Fig. 6V View FIGURE 6 ). Companion chaetae teardrop ( Fig. 6V View FIGURE 6 ) and sickle-shaped membranes within same torus ( Fig. 29A View FIGURE 29 ). Abdomen with 58 chaetigers (32–108). Abdominal chaetae broadly hooded ( Fig. 28G View FIGURE 28 ). Abdominal uncini with main fang surmounted by 8–10 rows of numerous minute teeth ( Fig. 6Q View FIGURE 6 ). Pygidium broadly rounded ( Fig. 4E View FIGURE 4 ) with two groups of purple eyespots. Tubes covered with sand grains, shell fragments, gravel, echinoderm spines and green algae.

GAMETES: Females from Nayarit ( México) with oocytes ( Fig. 6O View FIGURE 6 ) distributed along entire abdomen, visible though epithelium among chaetiger and torus. Male with sperm in abdomen with rounded nucleus, small acrosome, two rounded mitochondria and a long flagellum ( Fig. 6N View FIGURE 6 ).

SYMBIOSIS: Five large individuals (~ 8 cm length) from Punta Choya, Ángel de la Guardia Island, Coronados Island and Espíritu Santo Island in the Gulf of California, and Santa Cruz Island in California, USA, were found with several specimens of a cyclopoid copepod attached to the radioles, in the inner base of the branchial crown, dorsal lips and attached to the dorsal pockets of collar ( Fig. 6F–G View FIGURE 6 ). These copepods were identified as gastrodelphyid Gastrodelphys dalesi   Dudley, previously known from the crown of the sabellid polychaete Eudistylia polymorpha (Johnson)   from Zuma Beach, California (Green) and from E. vancouveri (Kinberg)   from Bodega Bay, California ( Gómez & Tovar-Hernández 2008).

Remarks. Megalomma circumspectum   was described by Moore (1923) as Branchiomma   from Santa Rosa

Island, California. It is distributed in Southern California, Western coast of Baja California Peninsula, Gulf of California and Nayarit, from intertidal waters to 80 m, in muddy or sandy muddy sediments. Megalomma circumspectum   , M. coloratum   , M. pigmentum   and M. splendidum   are common in California; among these M. coloratum   is unique by having a glandular ridge on chaetiger 3; M. pigmentum   has a caruncle; M. splendidum   has spiraled eyes only in dorsal radioles and M. circumspectum   is distinguished by having spherical eyes in most radioles.

Fourteen species of Megalomma   have radiolar eyes in most radioles (Appendix 1, Character 3, State 2). Among these species, M. acrophthalmos   , M. multioculatum   and M. phyllisae   have spiraled eyes in dorsalmost radioles; in M. perkinsi   eyes in these radiolar pair are oval and in M. circumspectum   , M. claparedei   , M. heterops   , M. lanigera   , M. pacifici   , M. sp., M. georgiense   n. sp., M. nechamae   , M. mushaense   and M. vesiculosum   these are spherical. Megalomma circumspectum   , M. pacifici   and M. georgiense   n. sp., share the presence of ocular spots in ventral radioles. In M. circumspectum   and M. pacifici   the dorsal margins of collar are fused to the faecal groove (not fused in M. georgiense   n. sp.). In M. circumspectum   the thoracic ventral shields are separated from tori and the length of handle in thoracic uncini is 1.5 times the length of main fang (all ventral shields in contact with tori and handle is two times the length of main fang in M. pacifici   ).

USNM

Smithsonian Institution, National Museum of Natural History

MBL

Museu Nacional de Historia Natural

ECOSUR

El Colegio de la Frontera Sur (Mexico)

PSS

Paleontology and Stratigraphic Section of the Geological Institute of the Mongolian Academy of Sciences

LACM

Natural History Museum of Los Angeles County

AHF

Allan Hancock Foundation, University of Southern California

T

Tavera, Department of Geology and Geophysics

V

Royal British Columbia Museum - Herbarium

Kingdom

Animalia

Phylum

Arthropoda

Class

Insecta

Order

Coleoptera

Family

Carabidae

Genus

Megalomma

Loc

Megalomma circumspectum ( Moore, 1923 )

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

Megalomma circumspectum

Hernandez-Alcantara, P. & Solis-Weiss, V. 1999: 29
Perkins, T. H. 1984: 363
Fauchald, K. 1972: 33
Hartman, O. 1969: 707
Rioja, E. 1962: 213
Hartman, O. 1961: 43
Hartman, O. 1959: 550
1959
Loc

Branchiomma circumspectum

Moore, J. P. 1923: 241
1923