Melinna cristata ZMBN
Creators: name: Gunton, Laetitia M.
name: Zhang, William
name: Kupriyanova, Elena K.
name: Hutchings, Pat A.
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Terebellida
Melinnidae
Melinna
Melinna cristata
Melinna albicincta

description: Melinna cristata (Sars, 1851)
Figs 9–12; Tables 4, 5
Sabellides cristata M. Sars, 1851: 205–206; 1856: 19–23, pl. 2, fig. 1–7.
Melinna albicincta Mackie & Pleijel, 1995
Melinna cristata Malmgren, 1866: 371–372, pl. 20, fig. 50.
For complete synonymy see Mackie & Pleijel, 1995.
Figs 6–8; Tables 4, 5
Material examined. AM W.21791, 3 specimens, including one prepared for SEM (AM W.21791.001), west of Salto, Kosterfjord, Sweden (59°00'N 11°00'E), mud, 110 m, coll. A. S. Mackie & F. Pleijel, 26 October 1989.
Melinna albicincta Mackie & Pleijel, 1995: 116–120, fig. 3, 5, table 1.
Material examined. Paratypes NMWZ1989­125 ­ 26, one mounted for SEM, NMWZ1989­125 ­ 22, type locality Southwest of Yttre Vattenholmen, Kosterfjord, Sweden (58°52'30"N 11°06'18"E), sand/mud/gravel, dredged from 60–80 m, coll. A.S. Mackie & F. Pleijel, 28 October 1989. AM W.21794, 1 specimen, collected same locality, same date, same collectors, sandy mud/stones/gravel, 40–50 m, dredge. In Mackie & Pleijel, 1995 this paratype is listed as AM W.21791, this is incorrect, the correct registration number for this specimen is AM W.21794.
Remarks
The redescription by Mackie & Pleijel (1995) only provided line drawings, here we give additional information based on light and SEM photographs.
Prostomium with well­defined anterior and posterior parts followed by an achaetous segment 1 with anterior elevated margin (Fig. 9A,B). Segments 2–5 with short row of acicular neurochaetae progressively becoming more laterally inserted (Fig. 9B). From segment 6 onwards neuropodia with uncini on raised tori (Fig. 11D). Notopodia present from segment 4 (chaetiger 3), very small with few notochaetae, gradually increasing in size and becoming conspicuous and laterally arranged by segment 7 onwards (Figs 9D, 10G, 11D, 12A,B,C). Notopodia bearing two tiers of notochaetae with finely spinulose surface (Fig. 11A,B). Dorsal membrane with at least 8 equal triangular projections (Figs 10B, 11C). A single pair of slightly curved dorsal hooks with prominent internal canal (Fig. 10B,C,D,E). Four pairs of branchiae (Fig. 10A,E), annulated with distinct longitudinal bands of cilia (Fig. 10F) and fused basally for about 10% of their length (Figs 9C,D, 10A,E, 11D). Thoracic neuropodia (Fig. 11D,E) raised, glandular tori with over 40 uncini, uncini with a single row of 3–4 teeth and a sub­rostral ornamented process (Fig. 11F,G). Rudimental notopodia on the abdomen as small rounded projections (Fig. 9F). Abdominal segments with elevated neuropodia decreasing in size posteriorly (Fig. 9E). Abdominal uncini with rostral tooth surrounded by strongly denticulated head (Fig. 12D,E). Pygidium with terminal anus, bounded by glandular lobes (Figs 9E,e, 12F,G) with no anal cirri. Methyl blue staining shows extensive ventral and lateral thoracic glandular areas (Fig. 9A,E). No tube present.
Remarks
The original description only provided line drawings, here we give additional information based on light and SEM photographs.
Prostomium with two elongate transverse nuchal slits (Fig. 6A,B). The first segment achaetous, forming a ventral collar with an elevated crenulated anterior margin (Fig. 6D). Segments 2, 3, 4 and 5 with neurochaetae as short acicular spines with neuropodia becoming more lateral, on segment 6 elongated raised tori with neurochaetae as uncini (Figs 6D, 7B). First notopodia on segment 4, very small with short capillary chaetae, and gradually becoming more dorsal and better developed by segment 6 with two tiers of capillary chaetae (as seen in chaetiger 11, Fig. 7C). This numbering of anterior segments differs from that given by Mackie & Pleijel (1995) as they did not recognize an achaetous segment 1 which forms a ventral glandular collar (Fig. 6D). Pair of short dorsal curved hooks (Fig. 6E, F). Four pairs of elongate branchiae ending in tapered pointed tips (Fig. 6A,D,E), with inner and anterior most pair basally fused (35–40%) (Figs 6E, 7E,F); two conspicuous white bands present on inner pairs (Fig. 6A,B) but absent on other branchiae. Segment 5 with dorsal membrane (Fig. 7E) bearing large number of small projections. Larger mid­dorsal papilla beneath dorsal membrane (Figs 6E, 7E,F), as also shown in Fig. 5A of Mackie & Pleijel (1995). Ventrum with anterior margins of segments elevated and glandular (Fig. 7A). Notopodia with elevated lobes and notochaetae arranged in two tiers (Fig. 8A,D). Anterior neuropodia forming raised tori with uncini arranged in a curved row (Fig. 7B), with four teeth in longitudinal row on chaetiger 11 and 13 (Figs 7D, 8B respectively). Rudimental notopodia on the abdomen as small rounded projections (Fig. 6C). Mid­ and posterior neuropodia becoming increasingly elevated (Fig. 8A,F). Abdominal uncini with four teeth in a longitudinal row (Fig. 8B,C,E). Pygidium with terminal anus and surrounded by a pair of large lateral lobes and a number of smaller ones (Fig. 8F). Living in muddy tube with attached shell fragments (Fig. 6G).
This numbering of anterior segments differs from that given by Mackie & Pleijel (1995) as they did not recognize an achaetous segment 1 forming a ventral glandular collar (Fig. 11D).
description: Published as part of Gunton, Laetitia M., Zhang, William, Kupriyanova, Elena K. & Hutchings, Pat A., 2023, New Species of Melinna (Melinnidae, Annelida) from the Australian Abyss with Comments on M. albicincta, M. cristata and M. elisabethae, pp. 125-154 in Records of the Australian Museum (Rec. Aust. Mus.) (Rec. Aust. Mus.) 75 (3) on pages 135-137, DOI: 10.3853/j.2201-4349.75.2023.1803, http://zenodo.org/record/10414060