Nephtys bangladeshi, Hossain, M. Belal & Hutchings, Pat, 2016

Hossain, M. Belal & Hutchings, Pat, 2016, Nephtys bangladeshi n. sp., a new species of Nephtyidae (Annelida: Phyllodocida) from Bangladesh coastal waters, Zootaxa 4079 (1), pp. 41-52 : 42-47

Nephtys bangladeshi n. sp.

( Figs 2 , 3, 4, 5; Table 1)

Material examined. HOLOTYPE: AM W.47794 (parapodia of chaetiger 3 removed and mounted for chaetal count), Bangladesh, Chairman Ghat, Noakhali, 22°30'48.3876"N, 91°5'6.6078"E, mid-intertidal zone from a tributary of Meghna Estuary, coll. Hossain, M.B, April 2015. PARATYPES: AM W.47795 (19 mm in length for 42 chaetigers, 1 mm width, parapodia of chaetigers 20, 35 removed and mounted for chaetal count), AM W.47796 (11 mm in length for 31 chaetiger, 0.8 mm width; parapodia of chaetigers 10, 25 removed and mounted for chaetal count), AM W.47797 (1 mounted for SEM), AM W.47798 (1 mounted for SEM), AM W.47799 (1 mounted for SEM), AM W.47800 (1 mounted for SEM), all from same location as holotype.

FIGURE 3. Nephtys bangladeshi n. sp. Line drawings under compound microscope: A. 10th chaetiger, B. 20th chaetiger, C. 25th chaetiger, D. 32th chaetiger. All scale bars 0.1 mm. ac = aciculum, b = branchia, dc = dorsal cirrus, nl = notopodial lobe, nel = neuropodial lobe, vc = ventral cirrus.

Diagnosis. Pharynx with 9 pairs of bifid terminal and 14 rows of subterminal papillae; each subterminal row with 5–7 papillae, mid-ventral simple terminal papilla and long mid-dorsal subterminal papilla present; verrucae absent; branchiae from chaetiger 7 to 27 occupying 3/4 of interramal space, completely absent posteriorly; distinct barred and capillary chaetae with spines present, lyrate chaetae absent.

Description. Holotype entire, body dorso-ventrally flattened, tapering posteriorly, pharynx not everted. Length 25 mm for 60 chaetigers, maximum width at 12th chaetiger 1.2 mm, excluding chaetae. Paratypes (incomplete) material ranges from 11–19 mm length, 0.8–1 mm wide for 31–42 chaetigers. Preserved body without pigmentation. Prostomium approximately square when pharynx not everted ( Fig. 2 A). Terminal antennae and palps of almost similar length present, palps ventral to the antennae ( Figs. 2 A & 4D). Nuchal organs not visible. Eyespots visible at level of chaetiger 2 but subdermal ( Fig. 2 A).

Pharynx not everted (examined by dissection of paratype material, AM W.47795), with 9 pairs of bifid terminal, 14 rows of subterminal papillae, each row with 5–7 papillae; mid-ventral simple terminal papilla and long mid-dorsal subterminal papilla present, verrucae absent; 1 pair of jaws present.

Parapodia biramous and well-developed (Fig. 3A–D) with long chaetae which become progressively longer posteriorly (Fig. 4D–F). First parapodia well demarcated, rudimentary and projecting anteriorly (Fig. 4A); dorsal and ventral cirri short, slender and poorly developed. Dorsal cirri of subsequent parapodia very short, papillae-like and swollen basally (Fig. 4B); Ventral cirri short and digitiform (Figs. 4B & 5C). Notopodia with conical and pointed acicular lobe (Figs. 3B & 4A). Aciculae large with pointed tips (Fig. 4A). Preacicular and postacicular lamellae less prominent, foliose and shorter than acicular lobes (Fig. 4B).

FIGURE 4. Nephtys bangladeshi n. sp. SEM photographs: A. Dorsal view of anterior chaetigers; B. Lateral view of chaetiger 4-6; C. Lateral view of chaetiger 7–9; D. Lateral view of chaetiger 13; E. Lateral view of chaetiger 17–19; F. Posterior chaetigers. An = antenna, s1 = 1st Chaetiger, b = branchia, p = palp, dc = dorsal cirrus, vc = ventral cirrus, pc = pygidial cirri (one missing). Scale bars: A, B, C, E = 100µm; D = 20 µm; F = 200 µm. (A, B, D from paratype AM W.47797; C, E, from paratype AM W.47798).

Chaetae of two types: barred chaetae ( Fig. 5 H) present in preacicular fascicle of anterior noto- and neuropodia; postacicular capillary chaetae with spines, spines visible only with SEM ( Fig. 5 D–F) and sporadically scattered (in irregular rows) along the tip of capillaries but bases and margins of these capillary chaetae free of spines ( Fig. 5 F). Short capillaries (basal margin smooth with only tip serrated) observed ( Fig. 5 D & G; short capillaries may represent emergent tips of developing chaetae of other types, see Dnestrovskaya & Jirkov 2011, pp. 4). Lyrate chaetae absent. Chaetal counts along body given in Table 1.

Chaetiger 3 Noto Pre-acicular 4 barred, 3 broad-bladed smooth capillaries Post-acicular 2 barred, 8 broad-bladed smooth capillaries Neuro Pre-acicular 2 barred, 3 broad-bladed smooth capillaries Post-acicular 3 barred, 2 broad-bladed smooth capillaries

Chaetiger 10 Noto Pre-acicular 9 barred, 10 broad-bladed smooth capillaries

Post-acicular 10 broad-bladed smooth capillaries Neuro Pre-acicular 3 barred, 8 broad-bladed smooth capillaries Post-acicular 2 barred, 12 broad-bladed smooth capillaries

Chaetiger 20 Noto Pre-acicular 9 broad-bladed smooth capillaries

Post-acicular 12 broad-bladed smooth capillaries Neuro Pre-acicular 12 broad-bladed smooth capillaries Post-acicular 16 broad-bladed smooth capillaries

Chaetiger 25 Noto Pre-acicular 11 broad-bladed smooth capillaries

Post-acicular 17 broad-bladed smooth capillaries Neuro Pre-acicular 10 broad-bladed smooth capillaries Post-acicular 15 broad-bladed smooth capillaries

Chaetiger 35 Noto Pre-acicular 15 broad-bladed smooth capillaries Post-acicular 14 broad-bladed smooth capillaries Neuro Pre-acicular 14 broad-bladed smooth capillaries Post-acicular 16 broad-bladed smooth capillaries Branchiae digitiform, present from chaetigers 7–27, absent posteriorly; slightly curved inwardly ( Figs. 2 C, 3B & 4D), increasing in size up to chaetigers 18–22 occupying ¾ of interramal space (Fig. 3B), then decreasing in size subsequently, completely absent from chaetiger 27 onwards ( Fig. 2 D & E). Interramal ciliated patches visible ( Fig. 2 C) only after staining with methylene blue, present on branchial and post-branchial chaetigers. One pair of pygidial cirri present (Fig. 4F).

Variation. Paratypes range from 11–19 mm in length, and 0.8–1 mm in width for 31–42 chaetigers, eye spots not visible in some paratypes.

Etymology. The new species N. bangladeshi n. sp. is Named after the country from which it was collected.

Habitat. Intertidal coastal mudflats, depth 0.5 to 1.5 m.

Type locality. Chairman Ghat, Noakhali, Bangladesh.

Distribution. Known only from the type locality.

Figures

FIGURE 2. Nephtys bangladeshi n. sp. A. Anterior dorsal view (paratype AM W. 47797); B. Lateral anterior view (holotype AM W. 47794); C. Lateral view of chaetigers 18 – 25 (holotype AM W. 47794); D & E. Lateral view of posterior chaetiger with no branchiae (holotype AM W. 47794). All scale bars 0.1 mm. a = acicula, an = antenna, b = branchia, cp = ciliated patches, e = eye.

FIGURE 5. Nephtys bangladeshi n. sp. SEM photographs: A. Neurochaetae from chaetiger 4; B. Notochaetae from chaetiger 8; C. Neurochaetae with no barred chaetae from chaetiger 35; D. Smooth broad-bladed capillaries, chaetiger 7; E. Spinose broad-bladed capillaries, chaetiger 20; F. Magnified view of broad-bladed capillary with spines, chaetiger 20; G. Magnified view of short capillary, chaetiger 20 H. Magnified view of barred chaetae, chaetiger 8. acl = acicular lobe, b = barred chaeta, sc = short broad-bladed smooth chaeta, bs = broad-bladed smooth chaeta, s = spine, vc = ventral cirrus, pol = post acicular lobe, np = notopodium, nep = neuropodium. Scale bars: A, B, C, F = 20 µm; D, E, H = 10 µm, G = 2 µm. All from AM W. 47797 except C, which is from paratype AM W. 47798.