Ampharete grubei Malmgren, 1865

Krüger, Lotte, Dietrich, Anna, Bastrop, Ralf & Bick, Andreas, 2022, From synonym to valid species: Redescriptions of Ampharete acutifrons (Grube, 1860) and A. cirrata Webster & Benedict, 1887, and brief descriptions of A. baltica Eliason, 1955 and A. grubei Malmgren, 1865 (Annelida: Terebellida: Ampharetidae), Zootaxa 5174 (4), pp. 357-380 : 374-375

Ampharete grubei Malmgren, 1865

( Fig. 11 )

Ampharete grubei Malmgren, 1865: 363–364 , Pl. 19, Fig. 44.

Material examined. Type material: Arctic , Svalbard, Edge Island , Storfjord, Whalers Point; 77°20’ N, 20°30’ E; depth 36–55 m, mud, Schwedisch Arctic Exp. 1864 sta. 00, SMNH-Type 5101 (6 paralectotypes) .

Diagnosis. Large species of up to 80 mm in length (see Malmgren 1865, but paralectotypes 27–50 mm) and up to 9 mm in width (paralectotypes 4.5–9 mm) ( Fig. 11A ). Twelve thoracic, two intermediate, and ten abdominal uncinigers with rounded or pointed short neuropodial cirri (see Remarks) ( Fig. 11E ). Prostomium triangular, anterior margin rounded. Buccal tentacles papillose ( Fig. 11B ). Branchiae arranged in two groups separated by a median gap of one to three branchial base width; three pairs in anterior transverse row and last pair in posterior position, directly below middle branchia of anterior transverse row. Paleae long, clearly protruding beyond prostomium, evenly tapering to long filiform tips, 10–20 each side ( Fig. 11A,B ). Pygidium with two lateral cirri and many long papillae; length of lateral cirri and papillae are almost the same (wide tubercle may be seen if the lateral cirri are broken or lost) ( Fig. 11D ).

Remarks. The body shape of paralectotypes, the form of paleae and the pygidium resemble those specimens of A. grubei depicted by Malmgren, 1865 (Plate XIX, Fig. 44). But in the original description no dorsal cirri were noted or shown, even though the specimens were much larger than paralectotypes (80 mm long). The form of dorsal cirri on intermediate and abdominal neuropodia varies depending on size of specimens: the pointed cirri present in smaller specimens (27–33 mm long) were about the same length as the base of respective neuropodium; while the rounded and shorter cirri present in larger specimens (50 mm long) were clearly shorter than the length of the base of respective neuropodium. Depending on the size of the specimens, small dorsal cirri may be present on at least the two last thorax segments as small pointed tips of the dorsal side of the neuropodia (3 specimens, 27–33 mm long). These were not observed on the larger specimens (37–50 mm). Short rounded dorsal cirri were present in the intermediate neuropodia of the specimen of 37 mm in length ( Fig. 11E ). On the largest specimens (50 mm long, 0.9 mm wide) dorsal cirri were not observed in the intermediate neuropodia ( Fig. 11C ).

Since the specimens of the type material of A. grubei and A. acutifrons differ significantly in many taxonomic characters, i.e., shape of paleae and presence of neuropodial cirri on abdominal segments, they are two different species. Therefore, A. grubei is a valid species and must be deleted from the synonym list of A. acutifrons .

Distribution. Only known from the type locality, Arctic, Svalbard.

Figures

FIGURE 11. Paralectotypes of Ampharete grubei Malmgren, 1865 (SMNH-Type 5101). Micrographs of methyl blue staining patterns and unstained individuals. A. Complete specimen, dorsal view. B. Anterior end with paleae, branchiae and buccal tentacles, ventral view. C. Last thoracic and both intermediate segments (XVII–XXX) of large specimen (50 mm long) without dorsal cirri on neuropodia, lateral view. D. Posterior end with lateral cirri and long anal papillae, ventral view. E. Last thoracic, intermediate and abdominal segments (XVIII–XXIX) of smaller specimen (37 mm long) with short dorsal cirri on neuropodia, lateral view. A–C: unstained. D, E: Methyl blue staining. Scale bars: A = 2 mm. B, D = 500 µm. C, E = 1 mm.