Pista Malmgren, 1866

Lavesque, Nicolas, Daffe, Guillemine, Londoño-Mesa, Mario H. & Hutchings, Pat, 2021, Revision of the French Terebellidae sensu stricto (Annelida, Terebelliformia), with descriptions of nine new species, Zootaxa 5038 (1), pp. 1-63: 39

publication ID

https://doi.org/10.11646/zootaxa.5038.1.1

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lsid:zoobank.org:pub:1C1E4C7A-2452-47BC-B843-2543135EF780

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http://treatment.plazi.org/id/03B887B1-6E11-FFEB-48F7-635A13EC96C1

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scientific name

Pista Malmgren, 1866
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Pista Malmgren, 1866  

Type-species: Amphitrite cristata Müller, 1776   by monotypy.

Diagnosis. (after Hutchings et al. 2021b). Transverse prostomium attached to dorsal surface of upper lip; basal part as a thick crest, eyespots sometimes present; distal part shelf-like. Buccal tentacles all uniformly cylindrical. Peristomium restricted to lips; upper lip relatively short, hood-like; lower lip swollen, cushion-like and mid-ventral. Segment I reduced dorsally, with pair of lobes of variable size and position; SG II–IV also with pairs of lobes of variable size and position, sometimes extending for a few more segments. Anterior segments highly glandular ventrally, with discrete, smooth to slightly corrugated, rectangular to trapezoidal mid-ventral shields. One, two or three pairs of arborescent, pectinate or plumous branchiae from SG II, typically two pairs, on SG II and III, less typically a single pair, and rarely 3 pairs. Conical to rectangular notopodia beginning on SG IV, typically extending for 17 segments, until SG XX; notochaetae all distally winged, frequently broadly-winged. Neuropodia beginning on SG V, as low ridges in conjunction with notopodia and short pinnules posteriorly; neurochaetae as long-handled avicular uncini, at least on anterior neuropodia, frequently until SG X or end of notopodia, then short-handled; uncini in partial to completely intercalated double rows on SG XI–XX, in a face-to-face arrangement. Nephridial papillae present on SG III, genital papillae on a variable number of segments, usually on SG VI–VII, posterior and dorsal to notopodia. Pygidium smooth to slightly crenulated.

Remarks. The genus Pista   is probably the most problematic one within the Terebellidae   s.s. The main issue concerns the diagnostic characters of the type species, P. cristata ( Müller, 1776)   . This species was reported around the world ( Hutchings & Lavesque 2020) because of: (1) a very brief original description and lack of type material, (2) a doubt concerning the number of pairs of branchiae and the arrangement of the branching filaments, and thus (3) confusion in several taxonomic keys. This species was described as having one pair of branchiae, while Malmgren who erected the genus Pista   and designated P. cristata   as the type species, stated that it has two pairs of branchiae. Some authors, as Jirkov & Leontovich (2017), have discussed the validity of the generic boundaries, trying to understand the vague information contained in the original description of this species. Nevertheless, since the type material does not exist, and since these authors did not revise material from type locality, their comments are not very helpful. Fortunately, one of the present authors (M.H.L-M) has recently examined material from the type locality (Kristiansand fjord, Norway) and will soon stabilize the taxonomic issues of this species by designating a neotype, in order to give not only a full description of the species, but also morphological boundaries of the genus (Londoño-Mesa et al. in prep.). Based on his observation, Pista cristata   is characterized by the presence of two pairs of pompom-like branchiae with tufts of branched filaments coming off the main stem (as followed by several authors: Nogueira et al. 2011; Mikac & Hutchings 2017; Labrune et al. 2019; Hutchings et al. 2021a, b), by the absence of dorsal ridges on SG II–III, by short lateral lobes on SG I and well-developed lateral lobes on SG II–IV, by uncini short-necked, with long-handle posterior process restricted until SG VIII, and finally by genital papillae present on SG VI–VII.