Trichobranchus hirsutus Hutchings, Nogueira & Carrerette, 2015, n. sp.
Creators: name: Hutchings, Pat
name: Nogueira, João Miguel Matos
name: Carrerette, Orlemir
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Terebellida
Trichobranchidae
Trichobranchus
Trichobranchus hirsutus

description: Trichobranchus hirsutus n. sp.
(Figs 1 I, 17–20)
Type material. Holotype: AM W.44608, MI QLD 2399, complete, in excellent state, 6 mm long, 0.6 mm maximum width. Paratypes: AM W.47510, MI QLD 2441, mounted on SEM pin; AM W.44610, MI QLD 2399; AM W.44624, MI QLD 2413; AM W.44946, MI QLD 2410 (13, plus1 mounted on microscope slide); AM W. 45142, MI QLD 2440 (7); AM W.45143, MI QLD 2440 (3); AM W.45147, MI QLD 2441 (2); AM W.45439, MI QLD 2441; AM W.45444, MI QLD 2444.
Description. Minute worms. In life with transparent body wall, base of branchiae bright red with well developed vascular system, buccal tentacles colourless (Fig. 1 I). Transverse prostomium attached to dorsal surface of upper lip; basal part with large eyespots laterally; distal part low, poorly developed, at base of upper lip (Figs 17 B, D–E, G, I–J; 18A, C). Deeply grooved buccal tentacles, in two thicknesses; under SEM, buccal tentacles highly ciliated on inner surface, annulated on outer side, with longitudinal track of cilia on each side (Figs 17 A–B, D–E, G–J; 18A–C; 19A–K). Peristomium forming lips; short, circular upper lip, as long as wide; short lower lip, continuing to form a pair of large flaring lobes terminating dorso-laterally (Figs 17 A–B, D–E, G– J; 18A–C; 19A–B, D–G, I, K). Segments 1–5 with progressively shorter lateral lobes, lobes triangular, distally rounded; anterior segments, until termination of notopodia, with thickened anterior margins laterally and ventrally, forming low lobes as short collars across ventrum covering posterior part of preceeding segment; segment 1 inconspicuous dorsally, with large eversible ventral process; anterior margins of segments 2–5 thickened dorsally, as raised crests, more developed on segments 2–3 (Figs 17 A–B, D–E, G–J; 18A–C; 19A–I, L). Two pairs of branchiae, on segments 2–3, each pair with single long and thick filament on either side; filaments annulated and heavily ciliated, second pair originating slightly laterally to first pair (Figs 17 B, D–E, G, I–J; 18A, C; 19B–D, F–H, K). Notopodia beginning from segment 6; narrowly-winged notochaetae on both rows, wings as short and fine hairs under SEM, chaetae in anterior row ~1/3 as long as those from posterior row (Figs 18 D–G; 19M; 20A–C). Neuropodia beginning from segment 6, totally sessile on thorax, uncini emerging directly from body wall, as foliaceous pinnules with well separated uncini on abdomen; few uncini per torus, ~10 until termination of notopodia, 10–15 on anterior abdominal segments, 6–8 posteriorly; neurochaetae as acicular uncini with four rows of minute secondary teeth and subrostral beard until end of notopodia (Figs 18 H; 20F–I); abdominal uncini avicular, with four rows of secondary teeth (Figs 18 I–J; 20J–L). Nephridial papilla absent; from segment 3, all segments with tuft of cilia between noto- and neuropodia, or corresponding position on segments 3–5 and after notopodia terminate, cilia longer on abdomen (Figs 19 B, D, F–G, M; 20A, D, J). Bilobed pygidium, heavily ciliated (Figs 17 A–F; 19B, D; 20D–E).
Remarks. Prior to this study ten species of Trichobranchus were known, of which five have two pairs of branchiae, a character shared with our new species, T. hirsutus n. sp. The major diagnostic characters are given in Table 4 of Hutchings & Peart (2000) and previously two species, T. bunnabus Hutchings & Peart, 2000 and T. gooreekis Hutchings & Peart, 2000, were known from Australia. Of these Australian species only T. bunnabus, which is only known from southern Australia, has two pairs of branchiae. Trichobranchus hirsutus n. sp. is a tiny species, much smaller than most species in this genus, including both previously known species from Australia, and it can easily be distinguished from T. bunnabus by the well developed triangular lateral lobes on segments 1–5, while in the latter species only the distal margins of the segments 2–4 are thickened. However, several species of Trichobranchus are poorly described as evident in Table 4 (Hutchings & Peart 2000), with some characters not being scored. This is the first record of the genus from the Lizard Island region.
Etymology. The specific name “ hirsutus ” is Latin and refers to the hairy buccal tentacles, branchiae and pygidium, and scattered tufts of cilia throughout body.
Habitat. Occurs in amongst coral rubble on intertidal reef flat.
Type locality. Coconut Beach, 14°40'52"S, 145°28'12"E, Lizard Island, Great Barrier Reef, Queensland, Australia.
Distribution. Known only from Lizard Island.
description: Published as part of Hutchings, Pat, Nogueira, João Miguel Matos & Carrerette, Orlemir, 2015, Telothelepodidae, Thelepodidae and Trichobranchidae (Annelida, Terebelliformia) from Lizard Island, Great Barrier Reef, Australia, pp. 240-274 in Zootaxa 4019 (1) on page 268, DOI: 10.11646/zootaxa.4019.1.12, http://zenodo.org/record/253393