Megalomma pigmentum Reish, 1963

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: 48-52

publication ID

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

persistent identifier

http://treatment.plazi.org/id/03CF87C4-2951-1251-FF5C-5AEBFD314416

treatment provided by

Felipe

scientific name

Megalomma pigmentum Reish, 1963
status

 

Megalomma pigmentum Reish, 1963  

Figures 22A–K View FIGURE 22 , 23A–O View FIGURE 23 , 28E View FIGURE 28 , 29E View FIGURE 29

Megalomma pigmentum Reish, 1963: 430–433   , Figs 16A–I View FIGURE 16 .— Knight-Jones, 1997: 314.

Megalomma monoculata Hartman-Schröder, 1965: 273–276   , Figs 276–278 fide Knight-Jones, 1997: 316.

Type material examined. [ USNM] 30451, holotype of Megalomma pigmentum Reish, 1963   , San Quintín Bay, Baja California, April 1960, Acc. No. 244910, Sta. 43, complete but crown separated from body. [ USNM] 30451, 8 paratypes of Megalomma pigmentum Reish, 1963   , San Quintín, Baja California, April 1960, Acc. No. 244910, Sta. 43. [ ZMH] P–5227 holotype of Megalomma monoculata Hartman-Schröder, 1965   , Topocalma, off south Chile, Exp. Mar Chile I, March 03, 1960, incomplete (lacking posterior abdomen). [ ECOSUR] topotypes, Baja California, México, San Quintín, Coll. L. E. Calderón, December 08, 1981 (16 specs).

Additional material examined. [ CSD – MBL] California, USA, B2, 4, January 1994, DN (1 spec.), A13, 4, 202, 1–28–86 (1 spec.), ITP   , Sta. I33–1, January 9, 2008, 31 m (2 specs), Survey 5300, Sta. I27, 1, January 3, 2008, 30 m, KL (1 spec.), Survey SB00, Sta. I–16–I, January 14, 2008, 29 m, VRV (1 spec.), Sta. 2140, July 18, 2007, 39 m, RML (1 spec.), ITP, I 15–2   , January 14, 2008, 31 m, RML (1 spec.), Survey OLDOUT Sta. A8–2, July 11, 2007, 61 m, RML (1 spec.). [ CSD – MBL]   California, USA, PLOO, Sta. A 13–1, 48.1 m, April 04, 1994 (1 spec.), Bight 98, 981077, Sta. 2230, 3.5 m, 08/5/1998 (1 spec.), Bight 03, 3971, Sta   . 4036, 48 m, July 23, 2003 (1 spec.). [ EMU]   Sinaloa, México, Topolobampo, EMU   4383, Coll. LIB, October 21, 1996 (2 specs); EMU   4400 (1 spec.). Bahía de Mazatlán , EMU   4550, Coll. LIB, December 08, 1996 (4 specs). Estero Urias , EMU   5073, Coll. LIB, February 26, 1997 (1 spec.); EMU   –5016 (26 specs); EMU – 5078 (1 spec.); EMU   –5052 (5 specs). [ LACM – AHF] California, USA, Velero IV, 003480, Cruise 97, Sta. 2152–52, 003480, 11.52 km 249º T   . from Redondo Beach Pier , 33º48’ 6’’ N, 118º 30’ 39’’ W, September 26, 1952 (2 specs). Santa Catalina Island, Avalon Harbor, St. 406 AVAL02 GoogleMaps   , SubID 3417, 33.34424º N, 118. 3225º W, Coll. Marine Pollution Studies Lab/Moss Landing Marine Laboratories, Invasive Species Survey, October 10, 2006, 10.3 m, coarse and sandy with shells (5 specs). South California 003472, N 2677 (1 spec.). Costa Rica, Velero III   , 003526, Sta. 477-35, Salinas Bay, 11º 03’ 20’’ N, 85º 43’ 30’’ W, 3.6 m, coarse sand, February 11, 1935, as M. roulei   (1 spec.). Perú, Velero III GoogleMaps   , 003528, Sta. 834–38, Off Independencia Bay, 14º 16’ S, 76º 10’ W, 38.4 m, mud, February 10, 1938, as M. roulei   (1 spec.). Velero III GoogleMaps   , 003527, Sta. 833–38, Off Independencia Bay, 14º 13’ S, 76º, 13’ W, 14.6 m, sand, shell, February 10, 1938, as M. roulei   (1 spec.). [ LACSD – MBL]   California, USA, D1D 3, 30 m   , 33° 46.02’ N, 118° 26.03’ W, September 21, 1973 (1 spec.). J1D 1, 30 m, 33° 46.02’ N, 118° 26.03’ W, January 21, 1976 (1 spec.). P8D 1, 30 m, 33° 42.44’ N, 118° 19.63’ W, July 16, 1979 (1 spec.). Q6D 1, 30 m, 33° 43.03’ N, 118° 20.82’ W, January 07, 1980 (1 spec.). PSCBE 06210 GoogleMaps   LA/TP, 34° 13.20’ N, 119° 22.43’ W, August 16, 1994, 26 m (1 spec.). 0799–OC3, 33° 48.44’ N, 118° 25.90’ W, July 20, 1999, 60 m (1 spec.). 0791–1B, 33° 44.98’ N, 118° 26.62’ W, July 12, 1991, 150 m (1 spec.). 0700–2B, 33° 44.07’ N, 118° 25.48’ W, July 11, 2000, 150 m (1 spec.). 0701–1B, 33° 44.98’ N, 118° 26.62’ W, July 18, 2001, 150 m (1 spec.). 0701–7D, 33° 42.83’ N, 118° 20.55’ W, July 18, 2001, 30 m (1 spec.). 0703–7D, 33° 42.83’ N, 118° 20.55’ W, July 09, 2003, 30 m (1 spec.). 0703–OD, 33° 48.14’ N, 118° 25.38’ W, July 10, 2003, 30 m (1 spec.). 0704–OD, 30 m, 33° 48.14’ N, 118° 25.38’ W, July 15, 2004 (1 spec.). [ MCZ 61884 View Materials ] Costa Rica, Punta Morales, no more available data (1 spec.) GoogleMaps   .

Diagnosis. Eyes only in dorsalmost radioles (spherical); dorsal margins of collar not fused to faecal groove; anterior peristomial ring exposed dorsally and laterally; base of branchial crown with ventral flanges; caruncle present; ventral shield of collar divided transversally in two parts; thoracic chaetae Type C; companion chaetae with teardrop and sickle-shaped membranes; abdominal chaetae narrowly hooded.

Description. Branchial crown longer than thorax with 14–16 pairs of radioles. Basal union of the radioles brown colored ( Fig. 22C View FIGURE 22 ). Radioles with four reddish-brown pigmented bands distributed over outer and lateral radiole margins and adjacent pinnules. Outer surfaces of radioles quadrangular basally, rounded distally. Base of the branchial crown with ventral translucent flanges ( Figs 22B–C, F View FIGURE 22 , 23B–D View FIGURE 23 ). Sub-distal compound eyes present only in the dorsalmost radiolar pair, spherical covering a short radiolar tip ( Figs 22H View FIGURE 22 , 23F View FIGURE 23 ). Other radioles with tips as long as equivalent space of eight pinnules ( Fig. 22I View FIGURE 22 ). Dorsal collar margins diagonal, not fused to faecal groove ( Figs 22A, E View FIGURE 22 , 23A, H View FIGURE 23 ). Dorsal lappets absent. Dorsal pockets absent ( Fig. 23A View FIGURE 23 ). Anterior peristomial ring exposed dorsally and laterally above collar ( Figs 22A, E, G View FIGURE 22 , 23A–B View FIGURE 23 ). Ventral lappets triangular, not overlapped ( Figs 22B, F View FIGURE 22 , 23B–D, G View FIGURE 23 ). Ventral shield of collar rectangular, divided transversally in two parts ( Figs 22B, F View FIGURE 22 , 23D, G View FIGURE 23 ). Lateral collar margins not covering bases of radioles ( Fig. 22C View FIGURE 22 , 23B View FIGURE 23 ). Dorsal lips purple dorsally, very long (about ¼ of branchial crown length), erect, with mid-rib forming two well developed lateral lamellae ( Fig. 22G View FIGURE 22 , 23E, H View FIGURE 23 ). Dorsal pinnular appendages present. Ventral lips small, rounded ( Fig. 23E View FIGURE 23 ). Caruncle long, erect, triangular, placed above mouth, between dorsal lips ( Fig. 23H View FIGURE 23 ). Ventral sacs prominent ( Fig. 23B–C, G View FIGURE 23 ) full of sand in most specimens. Keel absent. Body slender, cylindrical in thorax, flattened in abdomen. Total thorax-abdomen length 23 (37– 38) mm, maximum width 1 mm (1.5–1.8) mm throughout most of thorax. Seven thoracic chaetigers. Dorsal thoracic segments brown laterally. Thoracic tori of same length along thorax. Tori in chaetigers 2–3 short, occupying a half of the distance between notopodia and ventral shield margins ( Figs 22C View FIGURE 22 , 23B View FIGURE 23 ), not contacting shields. Superior thoracic chaetae elongate, narrowly hooded chaetae ( Fig. 23M–N View FIGURE 23 ); inferior thoracic chaetae Type C ( Figs 23L View FIGURE 23 , 28E View FIGURE 28 ). Eight thoracic uncini with crest surmounted by 6–8 rows of numerous minute teeth ( Fig. 29E View FIGURE 29 ), handles extending beyond base of shaft of companion chaetae, 2x length of main fang ( Fig. 23I View FIGURE 23 ). Companion chaetae with teardrop and sickle-shaped membranes within same torus ( Fig. 29F View FIGURE 29 ). Abdominal segments 63–83. Abdominal chaetae elongate, narrowly hooded chaetae ( Fig. 23O View FIGURE 23 ); chaetae in posterior row longer than those in anterior row. Abdominal uncini with main fang surmounted by 8–9 rows of numerous minute teeth ( Fig. 23K View FIGURE 23 ). Posterior margin of pygidium triangular ( Fig. 22J–K View FIGURE 22 ) without eyes. Tubes covered with sand grains ( Fig. 22D View FIGURE 22 ).

GAMETES: Females with the abdomen full of oocytes. Posterior abdominal chaetigers with nephridia visible, full with sperm tissue ( Fig. 23O View FIGURE 23 ). Sperm in posterior abdomen with a rounded nucleus, small acrosome, two rounded mitochondria and a long flagellum ( Fig. 23J View FIGURE 23 ).

Remarks. The original description of M. pigmentum   , did not include some details. The redescription provided here is to point out that in M. pigmentum   : 1) ventral basal flanges are present in the base of the branchial crown; 2) a caruncle is present, located above mouth between dorsal lips; 3) the anterior peristomial ring is exposed dorsally and laterally above collar; 4) dorsal margins of collar are not fused to the faecal groove and 5) it lacks dorsal pockets. Megalomma pigmentum   and M. gesae   are unique in having ventral basal flanges, mid-dorsal collar margins not fused to the faecal groove and radiolar eyes only in dorsalmost pair. Megalomma pigmentum   have caruncle and the ventral shield of collar is divided transversally in two parts (caruncle absent and ventral shield of collar entire in M. gesae   ).

The first records of M. pigmentum   outside its type locality were provided by Perkins (1984) from several localities of Florida and Venezuela. Tovar-Hernández and Salazar-Vallejo (1996) examined few specimens from Cumaná and Tampa recorded as M. pigmentum   but they found some characteristics different from those of M. pigmentum   . They recognized two undescribed morphs and called them as Megalomma sp. 1   (Cumana) and Megalomma sp. 2   (Tampa). Other Caribbean records of M. pigmentum   were not possible to review but a full revision of these materials is needed in order to confirm the amphi-american status of M. pigmentum   .

Knight-Jones (1997) synonymized M. pigmentum   and M. monoculata   , a species described from off south Chile but no comments were provided. During this study the holotype of M. monoculata   was re-examined. Both species have a caruncle, the peristomium is exposed dorsally and laterally above collar and eyes are only present in the dorsalmost radioles. New mounts of chaetae were not made since these were well illustrated in the original description. Megalomma pigmentum   and M. monoculata   are cryptic species, and no reproductive features have been studied in order to find any possible dissimilarity.

USNM

Smithsonian Institution, National Museum of Natural History

ZMH

Zoologisches Museum Hamburg

ECOSUR

El Colegio de la Frontera Sur (Mexico)

MBL

Museu Nacional de Historia Natural

EMU

Eastern Michigan University, T. L. Hankinson Vertebrate Museum

LACM

Natural History Museum of Los Angeles County

AHF

Allan Hancock Foundation, University of Southern California

T

Tavera, Department of Geology and Geophysics

MCZ

Museum of Comparative Zoology

Kingdom

Animalia

Phylum

Arthropoda

Class

Insecta

Order

Coleoptera

Family

Carabidae

Genus

Megalomma

Loc

Megalomma pigmentum Reish, 1963

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

Megalomma pigmentum

Reish, D. J. 1963: 433
1963