Sternaspis lindae, Salazar-Vallejo, 2017

Salazar-Vallejo, Sergio I., 2017, Cymonomus curvirostris Sakai 1965, Zoological Studies (Zool. Stud.) 56 (32), pp. 16-16 : 7-9

Sternaspis lindae sp. nov.

( Fig. 4 )

urn:lsid:zoobank.org:act:A157B737-7606-487E-9893-2B6E87B2F35F

Sternaspis fossor : Chamberlin 1919:405-406 (non Stimpson, 1853, partim).

Type material: Eastern Tropical Pacific , Panama. Holotype ( USNM 19478 ), and five paratypes ( USNM 1437649 ), RV Albatross, Gulf of Panama, Sta. 3391 (07°33'40"N, 79°43'20"W), 275 m, green mud, 9 Mar. 1891 (paratypes one previously dissected, body 12.5-14.5 mm long, 9.2- 10.5 mm wide, left shield plate 3.1-3.3 mm long, 3.0- 3.6 mm wide).

Additional material: Eastern Tropical Pacific. Panama. One specimen ( UMML 22-1035), 18 km E off Isla Iguana, R.V. Pillsbury, Cruise 6703, Sta. 502 (07°40'N, 79°50.5'W to 07°40.3'N, 79°50.9'W), 79- 77 m, 2 May 1967 (introvert partially exposed, body slightly macerated, 17 mm long, 7 mm wide, left shield plate 2.2 mm long, 2.4 mm wide). Three specimens ( UMML 22-1038), R.V. Pillsbury, Cruise 6703, Sta. 512 (07°31'N, 79°42'W), 210 m, 4 May 1967 (introvert exposed in two specimens, invaginated in the other, shield with bands defined, brownish and dirty pink; body 18-25 mm long, 10- 11 mm wide, left shield plate 3.5-3.8 mm long, 3.5-3.8 mm wide). One specimen ( UMML 22- 1043), 3 km SSE Taboga Island, R.V. Pillsbury, Cruise 6703, Sta. 483 (08°40.5'N, 79°30.7'W to 08°39.3'N, 79°31.7'W), 22-27 m, 1 May 1967 (juvenile, macerated, anal tube and gonopodial lobes eroded; body 14 mm long, 6 mm wide, shield left plate 1.4 mm long, 1.6 mm wide).

Colombia. One specimen ( UMML 22- 1045), Bahía Chupica, Chocó, R.V. Gillis, Sta. 9 (06°36.7'N, 77°27.4'W), mud and plant debris, 119-128 m, 16 Jan. 1972 (introvert invaginated, shield variegated, dirty orange and pale pink; body 15 mm long, 8 mm wide, left shield plate 2.6 mm long, 2.9 mm wide).

Description: Holotype ( USNM 19478) with body maculated, whitish with black spots of different size; introvert barely exposed, integument smooth ( Fig. 4A ); abdomen with fine, long papillae arranged in discontinuous single transverse series per segment. Body papillae minute, abundant, mostly short, larger in introvert. Body 12.5 mm long, 8.5 mm wide, about 28 segments.

Prostomium, peristomium and mouth not visible. Additional specimens ( UMML 22.1038) with prostomium hemispherical, opalescent. Peristomium rounded, projected at the mouth, with papillae covering its surface; lateral mouth areas smooth; surface behind prostomium smooth. Mouth circular, with minute papillae not extended up to first hook series.

Introvert exposing chaetae of chaetiger 3 and chaetae of chaetiger 2. Chaetiger 3 with 12 large, falcate thick hooks, distally broken ( Fig. 4B ) (entire, tapered, up to 20 in UMML 22.1038); hooks from chaetiger 2 with subdistal to medial darker areas. Genital papillae short, thick, tapered (digitate or basally swollen in UMML 22.1038), protrude ventrally from intersegmental groove between segments 7 and 8. Pre-shield region with 7 segments; capillary chaetae not seen, probably broken.

Shield reddish, paler towards the lateral and posterior margins, with ribs and concentric lines; suture visible throughout ¾ of shield, indistinct in the posterior region ( Fig. 4C ). Anterior margins rounded; anterior depression deep; anterior keels partly visible, not completely exposed. Lateral margins projected laterally, reduced posteriorly. Fan truncate, slightly projected beyond the poorly defined posterior corners, barely crenulated; median notch very shallow.

Marginal chaetal fascicles include 10 lateral ones, chaetae ovally arranged, and seven posterior ones, chaetae in a slightly curved arrangement. First two lateral fascicles emerge from dorsal edge of shield. Peg chaetae and additional thin capillaries present.

Branchiae and interbranchial filaments lost (one paratype with thin helicoid branchiae and thinner, straight interbranchial filaments). Branchial plate anteriorly expanded, truncate (rounded in one paratype), with about 16 rows of branchiae in its widest region ( Fig. 4D ).

Variation: Shields bands are more or less defined. Anterior corners are angular to blunt, anterior keels are visible in three out of five shields. Fans are medially notched, the posterior margin is slightly crenulate to denticulate, and the posterolateral corners are slightly projected, if at all. One juvenile ( UMML 22-1043) shows a shield with posterior fan margin denticulate.

Etymology: This species is after Linda Ward, good friend and colleague, because she has been very helpful and supportive of my research activities during many years. The epithet is a noun in the genitive case.

R e m a r k s: S t e r n a s p i s l i n d a e sp. nov. r e s e m b l e s S. r i e t s c h i ( Caullery, 1944) as redescribed elsewhere ( Sendall and Salazar-Vallejo 2013) because both species have shields with truncate fans and poorly defined posterior corners. They differ because in S. lindae the fan is smooth to barely crenulated, and the lateral margins are moderately projected laterally, whereas in S. rietschi the fan is crenulated and the lateral margins are markedly projected laterally. Further, S. lindae was found in 275 m depth in the Gulf of Panama, and S. riestschi was dredged in 1788 m depth in Indonesia. The specimens herein described were identified and recorded as Sternaspis fossor Stimpson, 1853 but in this species the fan is more projected posteriorly and concentric lines form distinct bands. Chamberlin (1919) indicated 10 specimens, but only 6 are available. On the other hand, the spotted pigmentation is apparently derived after some foreign component like ink or rubber seals stain, because it can be removed by brushing the body surface and cannot be regarded as diagnostic. The mottled pattern, if the stain has some affinity for glandular cells, would reveal their distribution including over the integument layer covering the shield. The additional specimens were not stained.

D i s t r i b u t i o n: Gulf of Panama, to NW Colombia, in muddy bottoms, 119-275 m water depth.

Figures

Fig. 4. Sternaspis lindae sp. nov. (A) Holotype (USNM 19478), ventral view. (B) Same, anterior end, frontal view. (C) Same, shield. (D) Same, branchial plate. (E-H) Paratypes (USNM 1437649), shields, E, F: Shields slightly cleaned by brushing off foreign particles and shield papillae, G: Another paratype, shield with left half cleaned, H: Same shield, after cleaning the right half. Scale bars: A = 1.8 mm, B = 1.2 mm, C-E = 1.3 mm, F = 1.1 mm, G, H = 1.5 mm.