Synelmis knoxi, Glasby, 2003

Glasby, Christopher J., 2003, A new species of Synelmis (Annelida, Polychaeta, Pilargidae) from New Zealand and designation of a neotype for S. albini from the Canary Islands, Zoosystema 25 (1), pp. 7-15 : 12-14

Synelmis knoxi n. sp.

( Fig. 2 )

Synelmis albini – Stull 1979: 29.

TYPE MATERIAL. — Holotype: New Zealand, M. V. Kokinga, off Twin Rocks, Bay of Islands , North Island, 35.17°S, 174.30°E, 46-73 m, 10.XII.1973 ( MONZ ZW 1457 ); paratypes: west coast of New Zealand, stn B473, 43.33°S, 169.78°E, 215 m, 3.VI.1961, 1 specimen ( MNHN POLY 1377 ); stn B686, 40.27°S, 172.54°E, 126 m, 8.X.1962, 1 specimen ( NIWA P-1280); stn C168, 39.67°S, 172.22°E, 284 m, 3.IX.1959, 8 specimens ( LACM-AHF POLY 2081 ); stn C169, 39.67°S, 172.42°E, 234 m, 3.IX.1959, 1 specimen ( NIWA P-1281); stn C438, 40°S, 173.61°E, 84 m, 7.V.1960, 1 specimen ( NIWA P-1282); stn S386A, 41.33°S, 170.68°E, 511 m, 4.II.1983, 1 specimen ( NIWA P-1283); stn S386C, 41.33°S, 170.68°E, 515 m, 4.II.1983, 1 specimen ( NIWA P-1284); stn S399C, 40.76°S, 171.33°E, 328 m, 9.II.1983, 1 specimen ( NIWA P-1285); stn V415B, 42.54°S, 170.50°E, 475 m, 5.IX.1992, 1 specimen ( NIWA P-1286).

TYPE LOCALITY. — Off Twin Rocks (35.17°S, 174.30°E), Bay of Islands, North Island, New Zealand.

ETYMOLOGY. — The species is named after Emeritus Professor George Knox for his great contribution to polychaete biology in the New Zealand region.

DISTRIBUTION. — Continental shelf and slope of New Zealand, currently known from north-east shelf of New Zealand and Challenger Plateau off west coast of New Zealand from 46 to 515 m depth.

DESCRIPTION

Holotype complete, 55 mm long, 1.0 mm wide at chaetiger 10; 158 chaetigers.

Body translucent, metalic sheen, creamy white, unpigmented. Body slender, long, dorsum highly arched, venter flatter with a deep, broad midventral groove; lateral grooves also present following line of parapodia to at least midbody ( Fig. 2A, B ). Prostomium rectangular, about two times wider than long. Three cirriform antennae; lateral ones extend anteriorly to tip of palps, located anteriorly over mid palps; median antenna slightly longer than lateral ones, about three quarters length prostomium ( Fig. 2A ). Two patches of eyespots on posterolateral prostomium, each four or five small oceli. Palps biarticulate, with spherical palpostyle. Slender palpal papilla arising from ventrolateral junction of palpophore and palpostyle, extends to level of palpostyle. Hindbrain bilobed, extends posteriorly to chaetiger 3. Pharynx evert- ed, revealing rim of very fine hairs (fimbriae); muscle bands of posterior portion visible through body wall, extending posteriorly to about chaetiger 5 (posterior margin); thereafter muscular oesophagus extends from chaetiger 5 to about chaetiger 30, where intestine begins.

Tentacular cirri cirriform, similar in size to parapodial cirri of anterior chaetigers. Parapodia with cirriform (slightly enlarged base) dorsal and ventral cirri, about three times length of corresponding chaetal lobe, dorsal and ventral ones equal in length for most of body; ventral ones slightly longer in posterior segments ( Fig. 2 C-E). Chaetal lobe rounded to squarish. Notopodial spines amber-coloured, very robust and slightly curved, some with a minute distal notch, tapering to blunt tip ( Fig. 2F ); from chaetiger 5 to penultimate chaetiger, one per parapodium, emerging from dorsal base of dorsal cirrus to half its length (in mid and posterior chaetigers). Neurochaetae include capillaries of varying lengths, longer ones with a finely serrated wing ( Fig. 2G ), shorter ones apparently wingless ( Fig. 2H ) (12 capillaries in anterior parapodia, reducing to six in posterior ones); furcate chaetae very short, barely extending beyond chaetal lobe, tines similar in length, longer one much stouter than other ( Fig. 2I ) (three or four furcate chaetae in anterior parapodia, numbers reducing posteriorly to two posteri- or ones). Notoaciculae considerably thinner than notopodial spine, two or three per parapodium. Neuroaciculae not visible.

Prepygidial region comprising a single achaetigerous segment (though cirri present). Pygidium bearing pair of cirriform anal cirri, slightly longer than preceding parapodial cirri ( Fig. 2B ).

Variation

Other material smaller ranging in size from about 10 mm long, 0.3 mm wide for 60 chaetigers to 36 mm long, 0.7 mm wide for 87 chaetigers (incomplete specimen). Eyespots apparently fade easily and specimens from same sample can have eyes present, either one pair of large lensed eyes, or two patches of several smaller eyespots, or pigmented eyespots may be absent. Palpal papilla may extend just beyond palpostyle. Lobes of hindbrain extend posteriorly to chaetiger 2 or 3. Pharynx extending posteriorly to chaetigers 5-9 (depending on degree of pharyngeal eversion). Notopodial spines first appear in chaetigers 4-6. Relative lengths of tines of furcate chaetae range from approximately equal to slightly subequal.

Specimen from station B473 is a mature male.

REMARKS

The material examined here includes the specimen identified by Stull (1979) as Synelmis albini (NIWA P-1280). Comparison of this specimen and further material from New Zealand with that of the Synelmis albini from the Canary Islands shows that the New Zealand specimens represent a new species. Synelmis knoxi n. sp. differs from Synelmis albini in having relatively longer cirriform antennae with the lateral ones arising from over the mid-palps, the muscular oesophagus extends more posteriorly, parapodial cirri are cirriform rather than fusiform, notopodial spines are amber-coloured and relatively more robust (three to four times thicker than corresponding notoacicula cf. about two times for S. albini ) and begin more anteriorly, and there are two or three notoaciculae per parapodium. Also S. knoxi n. sp. lacks glandular, pigmented parapodial cirri.

The other presently known species of Synelmis s.s. can be differentiated from Synelmis knoxi n. sp. as follows: Synelmis rigida differs from S. knoxi n. sp. in having fusiform antennae and parapodial cirri and in the later appearance of notopodial spines (chaetigers 13-23) (Salazar- Vallejo 2003); Synelmis sinica differs from S. knoxi n. sp. in lacking eyes, having a very poorlydeveloped chaetal lobe, in the later appearance of notopodial spines (chaetigers 12-15) and in having pigmentation spots on the lateral body.

Figures

FIG. 2. — Synelmis knoxi n. sp., holotype (MONZ ZW 1457); A, anterior end, dorsal view, pharynx fully everted (terminal fimbriae too small to be illustrated); B, posterior end, dorsal view; C, parapodium from chaetiger 7, right side, anterior view; D, parapodium from chaetiger 47, left side, posterior view; E, parapodium from chaetiger 130, left side, posterior view (notopodial spine broken); F, notopodial spine from parapodia of chaetiger 47; G, long capillary chaeta from parapodia of chaetiger 7; H, short capillary chaeta from parapodia of chaetiger 47; I, furcate chaeta from parapodia of chaetiger 7. Scale bars: A, B, 0.50 mm; C-E, 0.05 mm; F-I, 0.02 mm.