Cabira rangarajani, Mandal, Sumit, Harkantra, Sadanand N. & Salazar-Vallejo, Sergio I., 2007

Mandal, Sumit, Harkantra, Sadanand N. & Salazar-Vallejo, Sergio I., 2007, Cabira rangarajani n. sp. (Polychaeta: Pilargidae) from the Goa coast, central west coast of India, Zootaxa 1446, pp. 21-29 : 23-27

Cabira rangarajani n. sp.

Figures 1–3

Type material: Arabian Sea. Holotype (NIO-GLBMUR1) (16.5 mm long and 0.5 mm wide by chaetiger 10 with 59 chaetigers) and paratype (NIO-GLBMUR2) (14.1 mm long and 0.4 mm wide by chaetiger 10 with 55 chaetigers) collected in SASU-100, October 2005, cruise to the Goa coastal waters. Two complete specimens, collected off Marmagoa, 15°25’00” N, 73°43’00” E, 20 m, muddy-sand, October 2005.

Additional material: Cabira rangarajani n. sp., 8 anterior fragments were also collected at stations off Marmagoa, 15°29’00” N, 73°43’30” E; fine sand, 18 m; 15°24’03” N; 73°48’11” E; silty clay; 14 m; 15°24’46” N; 73°47’ 03” E; silty clay; 13 m, off Betul, 15°04’55” N, 73°51’74” E, silty clay, 23 m; 15°08’26” N, 73°51’11” E, silty clay, 20 m, salinity 33–34‰ in SASU 100, October 2005. At station 15°25’00” N, 73°43’00” E, 20 m, muddy-sand, apart from two complete specimens, 9 incomplete specimens collected at SASU 100, October 2005, cruise. In SASU 89, March 2005, cruise only one incomplete specimen was collected at the same station (15°25’00” N, 73°43’00” E, 20 m, muddy-sand). The specimens have also been deposited at the National Institute of Oceanography, India museum, under the registration number (NIO-GLB- MUR), with consecutive station numbers and collection date of the specimens.

Additional type material: India. Syntype of Ancistargis brevicirris Rangarajan, 1964 (CMFRI-73), another incomplete specimen collected at the same locality (Palk Bay, South India), 7 m, August 22, 1962. K. Rangarajan, collected July 12, 1961; it is 4.9 mm long, 0.5 mm wide, 27 chaetigers (other syntypes not available).

Cabira pilargiformis japonica Imajima, 1987 , an anterior fragment (ECOSUR-PILA 27), collected in Stat. 9-1, Ariake (33°08’ N, 130°08’ E), Japan, coll. E. Nishi.

Description: Holotype with body subcylindrical, dorso-ventrally flat (depressed); up to about chaetiger 16 dorsoventrally compressed, slightly rigid compared to remaining part of the body. Posteriorly flaccid, globular with large number of dark chromatophores from chaetiger 7, dispersed along the dorsal and ventral surfaces.

Prostomium bilobed, connected by smooth thin dorsal membrane. Two antennae, minute, conical, inserted on the lateral margin of the prostomium. Palpi short, flattened, arising from anterolateral margins of prostomium; palpostyle short, ventro-lateral ( Figs 1 a–c, 2a–b). Dorsal surface of palps, prostomium and peristomium covered with minute papillae, each almost square in shape ( Fig. 2 c). Proboscis everted, globular, thin; its surface covered by abundant short, conical, soft papillae. Eyes absent.

Peristomium anteriorly fused to prostomium, carrying two pairs of tentacular cirri, each short, conical, placed ventro-laterally; posteriorly demarcated from first chaetiger. First chaetiger smaller than subsequent ones ( Fig. 2 d).

Parapodia with short, conical dorsal and ventral cirri, each with one or two minute papillae, located near their base. Dorsal cirri present from chaetiger 1 and on all subsequent ones; ventral cirri present in chaetiger 1, small, conical bud. Dorsal and ventral cirri similar in size and shape throughout body.

Parapodia sub-biramous; notopodia with short, conical dorsal cirri, and single notopodial hooks ( Figs 1 d, 3a–b), similar in size throughout body. Neuropodia with short, capillaries. Notopodial hooks ( Fig. 1 e) emerge slightly ahead of dorsal cirrus. Notopodial hooks first appear at chaetiger seven. Neurochaetae of single type, 4–5 per ramus, long, slender, non-limbate, with entire tips ( Figs 1 f, 3c–d).

Pygidium tapering to conical lobe, with two lateral anal cirri, each digitate, covered with minute square papillae ( Figs 1 g, 2e–f). There was no variation in diagnostic characters between type and additional material examined.

Remarks: Cabira rangarajani n. sp., differs from C. brevicirris in the type of neurochaetae; however, in the original description, Rangarajan (1964:124–125) described three types of simple chaetae: a) non-limbate capillary chaetae, b) short chaetae with single row of minute teeth along cutting edge, and c) chaetae with cutting edge crenulated. Cabira rangarajani n. sp. has only a single type of non-limbate capillaries. The syntype was examined and its features were adequately detailed in the original description although it is brittle and difficult to examine. It has three types of neurochaetae, which is one of the important characters distinguishing Cabira rangarajani n. sp., from C. brevicirris . In addition C. rangarajani n. sp., differs from C. incerta Webster, 1879 in the relative size of the fused prostomium and peristomium and of the anterior end appendages such as palps and antennae. In C. rangarajani n. sp., the fused prostomium and peristomium is longer, about as long as the first 4 chaetigers, while it is about 2–3 chaetigers in C. incerta . In C. incerta the antennae are short, arising from swollen bases or ceratophores, indistinctly set off from prostomium, while in Cabira rangarajani the antennae are bud-like, inserted on the lateral sides of prostomium.

Neurochaetae Three types: 1. Non-limbate capillary; 2. Short chaetae with Only one type: non-limbate

single row of minute teeth along cutting edge; 3. Chaetae capillaries.

with cutting edge crenulated

* C. incerta was redescribed by Pettibone (1966) and re-examined by Wolf (1984). We follow their observations and remarks.

In the North-eastern Atlantic Ocean, there are apparently two different morphs of C. incerta ; one was described by Pettibone (1966) as having dorsal hooks, always present from chaetiger 7, and a single type of neurochaetae; the other morph was reported by Wolf (1984) with dorsal hooks present from chaetigers 7–8, and with two types of neurochaetae. As stated in the key below, this is an important difference to separate species and the Gulf of Mexico specimens must be described, but that is beyond the scope of this paper.

Ecological notes: This species live in fine sand to silty clay at depths of 18–23 m, in a salinity range of 33–34 ppt.

Etymology: This species is being named after K. Rangarajan in recognition of his publications on Indian polychaetes, and especially because he described the first species of Cabira from India.

Figures

FIGURE 1. Cabira rangarajani n. sp. Holotype NIO-GLBMUR 1 a) Anterior end, dorsal view; b) paratype NIO- GLBMUR 2, anterior end, dorsal view; c) holotype, anterior end, ventral view; d) holotype, chaetiger 8 with dorsal hooks and non-limbate capillary chaetae; e) holotype, dorsal hooks from chaetiger 7; f) holotype, neurochaetae from chaetiger 2; g) holotype, posterior end, dorsal view with two anal cirri (papillated) (scales. - a, c: 260 Μm; b, g: 130 Μm; d, e: 30 Μm; f: 20 Μm).

FIGURE 2. Cabira rangarajani n. sp. Holotype NIO-GLBMUR 1 a) Anterior end, dorsal view; b) anterior end, ventral view, c) anterior end, dorsal view (enlarged) showing papillae; d) chaetigers 1 – 2; e) posterior end, dorsal view showing anal cirri (papillated); f) posterior end (enlarged) (scales. - a, e: 260 Μm, b, d: 130 Μm; c, f: 65 Μm).

FIGURE 3. Cabira rangarajani n. sp. Holotype NIO-GLBMUR 1 a) Chaetiger 7 with dorsal hook and non limbate capillary neurochaetae; b) dorsal hooks from chaetiger 10; c – d) non-limbate capillary neurochaetae from different chaetigers (scales. - a – d: 20 Μm).