Sternaspis maior
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Ordo: Canalipalpata
Familia: Sternaspidae
Genus: Sternaspis
Name
Sternaspis maior Chamberlin, 1919 – Wikispecies link – Pensoft Profile
- Sternaspis maior Chamberlin, 1919: 406-407, Pl. 78, fig. 10.
- Sternaspis fossor: Fauchald 1972: 238–239, Méndez 2007[1]: 609, 614, 616 fig. 7 (partim, non Stimpson 1853[2]).
Type material
Eastern Tropical Pacific, Gulf of California. Neotype (UNAM 7882), RV El Puma, Crucero Talud V, Sta. 25 (24°52'N, 108°58'W), off Isla Altamura, Sinaloa, 830 m, 16-XII-2001, N. Méndez, coll. 1 paraneotype (UNAM 7881), RV El Puma, Crucero Talud V, Sta. 18 (24°15'N, 108°17'W), off Ensenada del Pabellón, Sinaloa, 965 m, 15-XII-2000, N. Méndez, coll. 1 paraneotype (UNAM 0000), RV El Puma, Crucero Talud XIV, Sta. 13 (28°31'34"N, 112°17'43"W), dredge, 180-182 m, 8-IV-0000, B. Yáñez, coll.
Description
Neotype (UNAM 7882), with body browinish, paler without the papillar layer (Fig. 11A, B). Introvert expanded, markedly wider than abdomen, covered with abundant small papillae. Abdomen with abundant, homogeneously distributed papillae. Body 17 mm long, 6 mm wide (complete paraneotypes 19.5–20.0 mm long, 7–10 mm wide), about 29 segments.
Prostomium hemispherical, paler than surrounding areas (Fig. 11C). Peristomium round, without papillae. Mouth oval, covered by papillae, restricted to a circular region around the mouth.
First three chaetigers with 12–14 golden, widely separated, falcate introvert hooks per bundle, each with subdistal dark areas (Fig. 11B, C). Genital papillae lost, eroded from the intersegmental groove between segments 7 and 8.
Pre-shield region with 7 segments, with papillae abundant, evenly distributed. No capillary chaetae seen.
Ventro-caudal shield with ribs, but no concentric lines; suture restricted to anterior region. Anterior margins rounded; anterior depression shallow; anterior keels not exposed (Fig. 11A, D). Lateral margins gently rounded, expanded posteriorly. Fan truncate, not extended beyond posterior shield corners, with a median notch, crenulated.
Marginal chaetal fascicles include 10 lateral ones (Fig. 11B, D), chaetae ovally arranged and 8 posterior fascicles, chaetae in linear arrangement. Peg chaetae on conical extensions emerging under shield corners. Peg chaetae with stout base in cross section; a small fascicle of delicate capillary chaetae (peg-associated capillary chaetae) between peg chaetae and first fascicle of posterior chaetae.
Branchiae numerous, thick, coiled, slender, long, protruding from two oval plates, separated by a wide angle, on either side of the anus. Additional fine, long filamentous papillae extending along the posterior margin of the shield.
Variation
The shield varies from dark reddish to orange (Fig. 11E–G) although their relative width varies depending on how heavily contracted the abdomen is, and how this contraction bends the lateral plates dorsally resulting in an apparently narrower looking shield. The main radial rib is very prominent, the fan is crenulated but it may be truncate, barely reaching the posterior corners (Fig. 11E, F), or projected beyond this corners (Fig. 11D, G).
Neotype locality
Off Isla Altamura, Sinaloa, Gulf of California, 830 m depth.
Remarks
Sternaspis maior Chamberlin, 1919 was very briefly described and the main distinguishing features were based upon the shield. Judging from the dimensions of the ventro-caudal shield (7 mm long, 15 mm wide), the original specimen must have been very large, but perhaps his specimen was severely damaged and only the shield could be characterized.
It is noteworthy that Chamberlin and Augener (1918, for Sternaspis africana, see above) almost simultaneously based their descriptions on schematic shield illustrations. Both illustrations indicate significant resemblances to the specific shields shape and ornamentations of Sternaspis maior. In both species, the shield was illustrated as having no concentric lines; for Sternaspis maior, the anterior depression had large keels, the main radial rib is quite distinct, and the fan has a median notch. These features are all present on the neotype such that we are confident we found the same species, and that this species is distinct. Thus, in order to clarify its taxonomic status (ICZN 1999[3], Art. 75.3.1), a neotype has been selected, described and its diagnostic features have been illustrated (ICZN 1999[3], Art. 75.3.2–75.3.3). Hartman (1938[4]: 3) emphasized that many type specimens which were supposedly deposited in Harvard, were not found in the collections and this includes the type materials of Sternaspis maior, such that we can conclude there is no type material available (ICZN 1999[3], Art. 75.3.4). We regard the neotype as conspecific with the specimen described in the original description (ICZN 1999[3], Art. 75.3.5). The original type locality was from the Gulf of California, south of Guaymas, Sonora (27°39'40"N, 111°00'30"W), 1143 m, and the proposed neotype was collected in a nearby locality, along the eastern Gulf of California coast, and in similar depths to the original material (ICZN 1999[3], Art. 75.3.6). The neotype and paraneotypes are deposited in the Marine Benthic Invertebrates Reference Collection of the Mazatlán Academic Unit, UNAM (ICZN 1999[3], Art. 75.3.7).
Sternaspis maior resembles Sternaspis affinis because both species have shields with round anterior margins, fan projected beyond the level of the posterior corners and with a median notch. The main difference relates to the presence of concentric lines which are barely visible in Sternaspis maior and distinct in Sternaspis affinis.
Distribution
Central part of the Gulf of California, México, in soft bottoms at 180–965 m, but the original material was collected at 1143 m.
Taxon Treatment
- Sendall, K; Salazar-Vallejo, S; 2013: Revision of Sternaspis Otto, 1821 (Polychaeta, Sternaspidae) ZooKeys, 286: 1-74. doi
Other References
- ↑ Méndez N (2007) Relationships between deep-water polychaete fauna and environmental factors in the southeastern Gulf of California, Mexico. Scientia Marina 71: 605-622.
- ↑ Stimpson W (1853) Synopsis of the marine Invertebrata of Grand Manan: or the region abou the mouth of the Bay of Fundy. Smithsonian Contributions to Knowledge 6: 5–67. [printed and distributed in March, 1853]
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 ICZN ( (1999) International Code of Zoological Nomenclature, 4th ed. International Trust for Zoological Nomenclature (The Natural History Museum), London, 306 pp. [http://www.iczn.org/iczn/index.jsp]
- ↑ Hartman O (1938) Annotated list of the types of polychaetous annelids in the Museum of Comparative Zoology. Bulletin of the Museum of Comparative Zoology, Harvard College 85: 1-31.
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