Sphaerodoropsis
Creators: name: Capa, Maria
name: Bakken, Torkild
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Phyllodocida
Sphaerodoridae
Sphaerodoropsis

description: Sphaerodoropsis sp.
Material examined. Western Australia: NMV F.162489 (1 spec.), Two Rocks region, 31º 41' 48'' S, 114º 52' 00'' E, 734 m, 5 Aug 2005.
Description. Measurements and general morphology. Body short and arched measuring 1.2 mm long and 0.5 mm wide, with 10 chaetigers. Dorsum convex and ventrum flattened, inconspicuous segmentation. Preserved specimen white with red fibrillar material in most macrotubercles.
Head. Retracted head, anterior appendages hard to observe in detail, but seem to consist of a median antenna, a pair of lateral antennae and a pair of palps.
Tubercles. Dorsal macrotubercles sessile and semispherical. First chaetiger with 4 macrotubercles, following chaetigers with 13 macrotubercles in double transversal rows, with six tubercles between parapodia, and seven on posterior row, macrotubercles of similar size, dorsal papillae not observed. Ventral surface with two longitudinal rows of large tubercles close to parapodia. Fibrillar material, as coiled treads, beneath the epidermis of most dorsal and ventral macrotubercles. Ventral spherical papillae in 4–6 longitudinal rows, arranged in double transversal rows per segment, and in a zig-zag pattern.
Parapodia. Parapodia wider than long. Acicular lobe only a low ridge anterior to chaetae, ventral cirri short rounded projecting beyond acicular lobe. Parapodial papillae not observed.
Chaetae. Compound chaetae present in all chaetigers in an arch posterior to acicular lobe, numbering 5–6 chaetae in each fascicle. Slender blades with recurved tip, 3–4 times longer than maximum width.
Pygidium. Pygidium with a pair of semispherical papillae, and a median rounded papilla, smaller than macrotubercles.
Reproductive features. No eggs, sperm or ‘copulatory organs’ observed.
Remarks. The single specimen is well preserved and is in good condition and seems to represent a different species than the others reported in this work. It belongs in Sphaerodoropsis group 3 (sensu Borowski 1994), and most closely resembles S. solis and S. fauchaldi, which are the Sphaerodoropsis species up to now described with longitudinal rows of ventral macrotubercles. The present specimen can be distinguished from S. fauchaldi by having a single ventral large tubercle close to the parapodia, while in S. fauchaldi there are two (or three) longitudinal rows on each side. It also has fewer dorsal macrotubercles, 6–7 per transversal row, compared to 12– 14 (8–10) in S. fauchaldi. In terms of dorsal macrotubercles the present specimen is more similar to S. solis, but has fewer ventral papillae per segment and seems to have shorter blades of chaetae than in S. solis. It should, however, be noted that the present specimen is small with only 10 chaetigers and presumably not fully grown. More specimens should be found before assessing the true identity of the species, in if appropriate describe it as new.
Distribution. South Western Australia (Fig. 15).
Ecology. Sand, 734 m depth.
description: Published as part of Capa, Maria & Bakken, Torkild, 2015, Revision of the Australian Sphaerodoridae (Annelida) including the description of four new species, pp. 227-267 in Zootaxa 4000 (2) on page 262, DOI: 10.11646/zootaxa.4000.2.3, http://zenodo.org/record/234762