Sternaspis africana Augener, 1918

Sendall, Kelly & Salazar-Vallejo, Sergio I., 2013, Revision of Sternaspis Otto, 1821 (Polychaeta, Sternaspidae), ZooKeys 286, pp. 1-74 : 23-26

Sternaspis africana Augener, 1918 stat. n. Figure 6

Sternaspis fossor var. Augener, 1918: 608-613, figs 109-110; Fauvel 1950: 342 (species list).

Sternaspis fossor africana : Petersen 2000: 321, Table 11.1.

Sternaspis scutata var. africana: Monro 1930: 179-180; Tebble 1955: 134-135; Kirkegaard 1959: 71-72; Guy 1964: 197; Intes and le Loeuff 1977: 234.

Sternaspis scutata : Jeldes and Lefevere 1959: 32; Rullier 1965: 52-53, fig. 11 (non Ranzani 1817).

Type material.

Neotype (NHM 1930.10.8.2582), R.V. Discovery Expedition, Angola, St. Paul Loanda, 08°47'S, 13°14'E, in 64-65 m, 4-VIII-1927.

Additional material.

Angola. 37 spec. (NHM 1930.10.8.2583-90), St. Paul Loanda, 08°47'S, 13°14'E, 64-65 m, 4-VIII-1927. Cameroon. 3 spec. (UMML 22.1036), off Malabo Island, R.V. Pillsbury, Cruise 6504, Sta. 259 (03°52'N, 08°54'E), 59 m, 16-V-1965. Democratic Republicof theCongo. 5 spec. (ECOSUR 2648), off Kipundji, 25 m, sand and mud, 25 Aug. 1965, A. Crosnier, coll. Côte d’Ivoire. 2 spec. (UMML 22.1041), off Grand Lahou, R. V. Pillsbury, Cruise 6405, Sta. 50 (04°58'N, 05°00'W), 160 m, 31-V-1964. Gabon. 1 spec. (NHM 1930.10.8.2581), Cape Lopez, 58-67 m, 8-X-1928. 33 spec. (IRFA-STE 01), Kipundji, 25 m, sand and mud, 25-VIII-1965, A. Crosnier, coll. Ghana. 1 spec. (NHM 1953.3.1.489-497), off Accra, Stn 130. 2 spec. (NHM 1953.3.1.489-497), off Accra, Stn 28. Two spec. (NHM 1953.3.1.489-497), off Accra, Stn 47. 1 spec. (NHM 1953.3.1.489-497), off Accra, Stn 59. 2 spec. (NHM 1953.3.1.489-497), off Accra, Stn 71. Nigeria. 1 spec. (UMML 22.1034), off Bonny, R.V. Pillsbury, Cruise 6504, Sta. 254 (03°51'N, 07°10'E), 161 m, 14-V-1965. 1 spec. (UMML 22.1037), off Burutu river mouth, R.V. Pillsbury, Cruise 6504, Sta. 236 (05°19'N, 04°47'E), 114 m, 12-V-1965. 1 spec. (UMML 22.1044), off Burutu river mouth, R.V. Pillsbury, Cruise 6504, Sta. 237 (05°19'N, 04°48'E), 101 m, 14-V-1965.

Description.

Neotype (NHM 1930.10.8.2582-90) with body smooth, clean, white, leathery. From segments 6-7, body with minute papillae dense on segments 7 and 8, but evenly spaced in other segments. Well-defined clusters of cuticular papillae in single row starting on segment 8, encircling each segment to posterior end, includ ing last segments opposite ventro-caudal shield. Body up to 20 mm long, 7 mm wide, about 28 segments.

Prostomium oval, hemispherical, opalescent, translucent (Fig. 6A). Peristomium rounded, raised at the position of mouth and with papillae sparsely covering most of surface. Mouth circular, completely covered by minute papillae, situated halfway between prostomium and anterior border of second segment.

First three chaetigers with 15-20 slender, bronze, slightly falcate hooks in a closely apposed group; hooks without dark areas. One pair of slender translucent genital papillae in intersegmental groove between segments 7 and 8. Pre-shield region with 7 segments, with short couplets of fine capillary chaetae protruding from body wall.

Ventro-caudal shield ribs poorly developed, concentric lines not visible; suture indistinct. Anterior margins angular; anterior depression deep; anterior keels not exposed (Fig. 6B). Lateral margins rounded, expanded medially, reduced posteriorly. Fan barely reaching posterior shield corners, medially projected, denticulated.

Marginal chaetal fascicles include nine lateral ones, chaetae in oval arrangement, and five posterior fascicles, chaetae in a slightly curved arrangement and with each fascicle parallel to next. Peg chaetae long, emerge from an extended fleshy cone; a small fascicle of delicate capillary chaetae emerge from the base of the fleshy cone bearing peg chaetae.

Branchiae mostly eroded, placed on oval, wide branchial plates (Fig. 6C).

Variation.

The ventro-caudal shield is medially fused; its fan is slightly projected beyond the posterior margin and its margins are denticulated (Fig. 6 D–F). The posterior corners are rounded and never prominent or reaching the fan posterior margin level. Larger specimens may have a median notch and their body papillae are eroded. As originally indicated by Augener (1918: 162-163), the introvert hooks are always thin, abundant and without the subdistal mark which is common in other species in the genus.

Neotype locality.

Angola, St. Paul Loanda.

Remarks.

Augener (1918) proposed Sternaspis fossor var. africana for specimens found along the tropical and subtropical Western and southwestern coast of Africa. This species has been regarded as a junior synonym of Sternaspis scutata (Ranzani, 1817), a species originally described from the Mediterranean Sea; however, the shields are so different that in order to clarify the status for the Western African species, a neotype is being proposed ( ICZN 1999, Art. 75.3.1). The description above and the corresponding illustration characterize the main diagnostic features ( ICZN 1999, Art. 75.3.2-75.3.3).

Hermann Augener was a volunteer worker in the Hamburg Museum ( CCAM 1938), where he deposited most of his materials; unfortunately, after WWII bombing many type material lots were lost and this included the type series of Sternaspis fossor var. africana, as confirmed by the museum staff ( ICZN 1999, Art. 75.3.4). According to the original description and illustrations by Augener (1918), the ventro-caudal shield has a median fan projection which is unique among the species in the genus; this feature is clearly shown by the neotype and consequently we regard it as consistent with the original type material ( ICZN 1999, Art. 75.3.5). Further, the original type localities included a series of places like Senegal, French Guinea, Liberia, Ivory Coast, Gold Coast, Nigeria, French Equatorial Africa, Congo, and Angola, and the proposed neo type was collected in Angola ( ICZN 1999, Art. 75.3.6). The neotype has been deposited in the Natural History Museum, London ( ICZN 1999, Art. 75.3.7). The original name was introduced as a variety; however, after Art. 45.6.4 ( ICZN 1999), the name has subspecific status, as has been listed by Petersen (2000: 321), and consequently we can propose its elevation to species rank.

Sternaspis africana Augener, 1918 n. status, resembles Sternaspis spinosa because both have shields with deep anterior depressions and markedly expanded lateral shield margins. However, the shield integument is thick in Sternaspis africana such that the ribs are barely visible, whereas in Sternaspis spinosa the integument is transparent and both ribs and concentric lines are visible. Further, it resembles the only other species having a shield with a denticulate posterior margin: Sternaspis andamanensis sp. n., but besides the differences in body papillation which is evident in Sternaspis africana and lacking in Sternaspis andamanensis , their shields also differ. In Sternaspis africana the anterior margins are projected slightly beyond the anterior depression, the fan is not projected medially and there are no lateral notches, whereas in Sternaspis andamanensis the anterior margins are markedly projected from the anterior depression, and the fan is markedly projected medially and lateral notches are deep.

Distribution.

Western African coast, from Ghana to Angola, 20-70 m.