Sternaspis affinis

The morphological monograph of Vejdovsky (1882), apparently on S. 'scutata', was based on the species S. thalassemoides Otto according to Sendall & Salazar-Vallejo (2013)

 (Based on best syntype). Body with first six segments smooth, pale, without cuticular papillae (Fig. 10A). Segments seven and eight with many small cuticular papillae, decreasing in density ventrally on remaining posterior segments, more numerous on the dorsal surface opposite the shield. Single rows of clusters of longer filamentous cuticular papillae present especially dorsally near ventro-caudal shield (Fig. 10D). Body 10 mm long, 5.5 mm wide, 30 segments.   Prostomium hemispherical, opalescent, finely granular. Peristomium round, flattened at mouth, without papillae. Mouth oval, covered by papillae, extends from edge of prostomium to the anterior border of segment 2 (Fig. 10B).   First three chaetigers with six to 12–14 bronze, slightly falcate introvert hooks, each with subdistal dark areas. Genital papillae protrude ventrally from intersegmental groove between segments 7 and 8. Pre-shield region with 7 segmentswithout chaetae.  Ventro-caudal shield rust red, with fine oblique ribs, and regularly spaced concentric lines; suture extended throughout shield (Fig. 10C); dried out syntypes with a darker, blackish shield (Fig. 10E). Anterior margins rounded; anterior depression deep; anterior keels not exposed. Lateral margins expanded posteriorly. Fan truncate, margin smooth, slightly sigmoid, with two shallow lateral, and median deeper notches.   Marginal chaetal fascicles include 10 lateral ones, ovally arranged, and six posterior fascicles, also in oval arrangement. Chaetae of fascicles nine and ten are about 1.5 x the length of the remaining lateral fascicles. Peg chaetae short, broad, oval in cross section at the base. Additional delicate capillary chaetae between peg chaetae and first posterior fascicle of shield chaetae.  Branchiae coiled filaments, emerge from two branchial plates, oriented close to parallel. Few long filamentous interbranchial papillae among branchiae.

 Neotype (CMNH ZW-120) with body colour creamy white to yellow-white, sometimes more grey, with first six segments lighter, becoming darker when dried out (Fig. 8A). Cuticle mostly with short filamentous papillae, somewhat longer on segments seven and eight. Rows of clustered filamentous papillae usually in two loosely arranged, lateral rows per segment, more noticeable on posterior segments dorsal to ventro-caudal shield. Body up to 22 mm long, 10 mm wide, about 29 segments.   Prostomium small, hemispherical, slightly opalescent. Peristomium rounded, raised at mouth, with some papillae between mouth and prostomium. Mouth densely papillate, slightly oval, positioned halfway between prostomium and anterior edge of segment 2.  First three chaetigers with 10 bronze, slightly falcate, introvert hooks with about another five smaller hooks ventral to larger hooks. Hooks widely separated (widely apposed), with subdistal dark areas. One pair of genital papillae protrude ventrally from intersegmental furrow between segments 7 and 8. Pre-shield region with 7 segments, with small fascicles of fine short capillary chaetae laterally in some specimens.  Ventro-caudal shield dark orange, often covered with sediment; ribs and concentric lines visible; suture extended throughout the shield (Figs 1B, 8B–E). Anterior margins rounded; anterior depression shallow; anterior keels not exposed. Lateral margins rounded, expanded posteriorly. Fan slightly projected posteriorly, markedly notched medially.   Marginal chaetal fascicles include 10 lateral ones, chaetae in a narrow oval arrangement, and five posterior fascicles in an offset linear arrangement; chaetae curving towards midline. Peg chaetae long, with a narrow base in cross section, emerge from cuticle almost at same level as margin of shield. Two additional groups of delicate chaetae between peg chaetae and first bundle of posterior shield chaetae.  Branchiae numerous, coiled and protrude from two plates widely separated dorsally.

 Neotype (RBCM 005-138-001), with body cream to light tan, sometimes greyish (Fig. 5A, B). First six segments smooth with a few minute cuticular papillae widely and evenly spaced. Remaining segments more papillate and opaque in appearance. Segments seven and eight slightly more opaque and dense than preceding ones, with stout cuticular papillae especially near genital papillae, some cuticular papillae with small grains of sediment adhered to bases. Body 15.5 mm long, 5.0 mm wide (other specimens up to 22 mm long, 7 mm wide), about 29 segments.   Prostomium hemispherical, opalescent, translucent, sometimes with crescent shaped red eyespots laterally on smaller individuals (Fig. 5C, insert). Peristomium round, without papillae. Mouth oval, covered by papillae, extending from base of prostomium to anterior edge of second segment.   First three chaetigers with 8–14 light bronze, widely separated, slightly falcate introvert hooks per bundle, each with subdistal dark areas (Fig. 5C). Genital papillae protrude ventrolaterally from intersegmental groove between segments 7 and 8.   Pre-shield region with 7 segments, with papillae evenly spaced, slightly denser than on anterior segments, although less so ventrally, and in single rows of clusters of short filaments closer to ventro-caudal shield, especially on dorsal surface, rarely showing delicate short capillary chaetae protruding laterally from body wall.  Ventro-caudal shield with concentric lines, slightly ribbed; suture extended throughout shield (restricted to the anterior region in larger specimens). Anterior margins rounded; anterior depression deep; anterior keels not exposed (Figs 1B, 2, 5B, D). Lateral margins gently rounded (straighter in larger specimens), not expanding posteriorly. Fan truncate, almost straight in juveniles, sometimes with median notch, becoming crenulated in larger specimens.   Marginal chaetal fascicles include 10 lateral ones (Fig. 5E), chaetae ovally arranged, and five posterior fascicles, chaetae in a linear arrangement. Peg chaetae on conical extensions emerging under most prominent oblique rib of the shield. 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 anus. Additional fine, long filamentous papillae extending to lateral and posterior margins of shield.

 Body colour off-white or grey in alcohol (Fig. 4A–D); papillae minute, especially behind segment 7 and near shield on dorsal side, or smooth, apparently without papillae. Anterior region often swollen and bulbous, sometimes wider than posterior region, with a constriction at septum between segments 7 and 8 (Fig. 4D). Neotype 14.6 mm long (paraneotypes 11.9–17.0 mm long), 12 mm wide, with about 30 segments.   Prostomium small, without eyespots. Peristomium rounded, flattening at position of the mouth and devoid of any papillae. Mouth circular, completely covered with minute papillae, extends from prostomium to the edge of segment 2 (Fig. 4D).   First three chaetigers with more than 12–14 hooks, bronze with subdistal dark band (Fig. 4E). Genital papillae between segments 7–8 (Fig. 4B–D). Pre-shield region with 7 segments, sometimes bearing small fascicles of fine capillary chaetae.   Ventro-caudal shield with radiating oblique ribs and concentric lines; suture restricted to anterior region (Figs 1B, 4B, C, F). Anterior margins rounded; anterior depression deep; anterior keels not exposed. Lateral margins slightly expanding posteriorly. Fan truncate, not extending beyond posterior corners, crenulated, slightly projected outwardly, especially in larger individuals; median notch shallow.   Marginal chaetal fascicles include 10 lateral ones, chaetae ovally arranged, and six posterior fascicles, chaetae in a slightly curved arrangement. First two lateral fascicles emerge from ventral edge of shield. Lateral fascicles with long hirsute chaetae. Peg chaetae not seen.  Branchiae spirally twisted, abundant, variably eroded (Fig. 4A, B, C, F). 

 Sternaspis scutata is a stout burrowing worm, whitish-grey in colour, with a leathery texture. Its body is up to 3.5 cm in length and 1-1.5 cm wide. The body is divided into 20-22 segments, the first seven forming the anterior region, the remainder forming the posterior region. The anterior region is much smaller and narrower than the posterior region into which it can withdraw. The head is reduced and bears a small translucent rounded prostomium above the mouth. The first segment behind the head forms a peristomium that is covered by short papillae. Numerous long, slender, occasionally spiralled gills extend from the posterior.

Neotype locality off coast of Turkey (see Thalassema scutatus for details). Reported global distributions are unlikely to be correct, but are indicative of the accumulated literature occurrences. Sendall & Salazar-Vallejo (2013 advise: "Mediterranean Sea to the English Channel, 9–36 m depth. Deeper water records from the Eastern Mediterranean (Ben-Eliahu and Fiege 1995) deserve a careful comparison to define if they are conspecific with the shallow water material. Some records from non-Mediterranean or Northeastern Atlantic localities might belong to other, probably undescribed species."

 Apparently restricted to the Norwegian Sea and Northeast Atlantic Ocean around Iceland and the Faroe Islands, 7–226 m depth.

 Southern Sakhalin Island (Russia), Japan, and the Philippines, 20–70 m depth. The record for estuarine environments in India (Southern 1921: 649–651, Pl. 20, fig. 5a, b) is questionable; the illustration resembles the species but there are some subtle differences. Therefore, we are doubtful about the distribution extending to estuarine waters in the Bay of Bengal.

 Alaska, USA (in the Gulf of Alaska) south along the coast and inland waters to Monterey, California, USA, and into the Gulf of California. This species, identified as Sternaspis fossor, has been regarded as one of the most abundant ones along the coast in the East Sound of the San Juan Islands (Weese and Macnab 1930), and along the Washington coast in 95–154 m with sediment having 50–68% mud (Lie and Kisker 1970). Moore (1923: 218) reported two species from Southern California, based upon the number of chaetal fascicles along the shield margins; one with 16 total bundles found in 441–492 m, and the other, smaller in size, with 15 total bundles and collected in sediments at 92–1190 m. 

As currently understood probably shallow water only.

Depth range based on 39 specimens in 1 taxon.
Water temperature and chemistry ranges based on 21 samples.

Environmental ranges
  Depth range (m): 0 - 555
  Temperature range (°C): 6.640 - 10.151
  Nitrate (umol/L): 6.725 - 22.690
  Salinity (PPS): 31.692 - 33.114
  Oxygen (ml/l): 3.837 - 6.616
  Phosphate (umol/l): 0.943 - 2.182
  Silicate (umol/l): 15.658 - 51.234

Graphical representation

Depth range (m): 0 - 555

Temperature range (°C): 6.640 - 10.151

Nitrate (umol/L): 6.725 - 22.690

Salinity (PPS): 31.692 - 33.114

Oxygen (ml/l): 3.837 - 6.616

Phosphate (umol/l): 0.943 - 2.182

Silicate (umol/l): 15.658 - 51.234
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

 Sternaspis scutata inhabits sandy and muddy substrata, where it burrows head-down, exposing the gills on its posterior end.

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 2
Specimens with Barcodes: 42
Species With Barcodes: 1

The following is a representative barcode sequence, the centroid of all available sequences for this species.

There are 2 barcode sequences available from BOLD and GenBank.  Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

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