Lagis crenulatus, Sun, Yanan & Qiu, Jian-Wen, 2012

Sun, Yanan & Qiu, Jian-Wen, 2012, A new species of Lagis (Polychaeta: Pectinariidae) from Hong Kong, Zootaxa 3264, pp. 61-68 : 63-66

Lagis crenulatus sp. nov.

( Figs. 2–4 , Table 1 )

Material examined. 22 type specimens, all specimens were collected from a mud flat in the Mai Po Inner Deep Bay Ramsar Site, Hong Kong (22°30'N 114°02'E). Holotype: IOCAS MBM 119742, February 2009 (1 complete specimen with tube). Paratypes: IOCAS MBM 119743 (1 complete specimen with tube fragments), IOCAS MBM 119744 (1 complete specimen with tube fragments), IOCAS MBM 119745 (1 specimen with anterior end only), IOCAS MBM 119746 (1 specimen with anterior end only), IOCAS MBM 119747 (1 specimen with anterior end only), IOCAS MBM 119748 (1 complete specimen), IOCAS MBM 119749 (1 complete specimen), IOCAS MBM 119750 (1 complete specimen), IOCAS MBM 119751 (1 complete specimen), IOCAS MBM 119752 (1 complete specimen with tube, worm prepared for SEM), AM W38672 (1 complete specimen), AM W38673 (1 complete specimen), AM W38674 (1 complete specimen), AM W38675 (1 complete specimen with tube fragment), AM W38676 (1 complete specimen), AM W38677 (1 specimen with anterior end only), AM W38678 (1 complete specimen with tube, worm prepared for SEM), AM W38679 (1 complete specimen with tube), AM W.38680 (1 complete specimen with tube fragments), February 2009; AM W38681 (1 complete specimen), AM W38682 (1 specimen with tube, posterior end of worm prepared for SEM), May 2010.

Etymology. The specific name crenulatus is derived from the Latin word crena, which describes the notched margins of the scaphe.

Diagnosis. Rim of cephalic veil partially fused to operculum, with numerous short cirri. Raised operculum margin smooth. Chaetigerous/Uncinigerous formula 16/12. Thoracic branchiae absent. Notochaetae capillary of two types; long ones with numerous short hairs on one side from shaft to tip; short ones with numerous short hairs subdistally on one side of shaft and pectinated distally. Uncini with major teeth in 4 vertical rows. Scaphe with crenulated margins. Scaphal hooks curved with a sharp tip.

Description based on holotype. Tube conical, straight, friable, composed of sand grains held by yellowish cement ( Fig. 2 ). Length 12 mm, width 2.5 mm. Specimens in alcohol pale white. Body wall transparent with sediment contents inside gut clearly seen.

Body short, conical, tapering towards scaphe. Length 11.8 mm, width 2.14 mm. Rim of cephalic veil with 14 short digitiform papillae ( Fig. 3 A). Cephalic veil partially fused to operculum, funnel-shaped, surrounding peristomial palps. Peristomial palps numerous, grooved.

Opercular margin raised, smooth. Operculum with 11 pairs of golden paleae fan-shaped on each side, with middle ones longer than lateral ones ( Figs 3 A, 4A). Each palea pointed gradually, tapering to a fine rolled-in tip. First pair of tentacular cirri inserted on anterior edge of segment 1. Second pair of tentacular cirri arising from connecting ridge running across venter of segment 2. Anterior margin of connecting ridge incised, forming glandular lobes. Segment 2 without postero-dorsal lobe. Anteroventral edge of segments 3–5 slightly protruded forward to cover posterior part of previous segment. Segments 3–4 without branchiae. Midventral glandular patches present on segments 2–5. Segment 6 with a narrow, thin, slightly glandular anteroventral lobe with smooth anterior margin.

Chaetigers 1–3 and chaetiger 16 with notopodia and notochaetae only. Chaetigers 4–15 biramous with notopodia and neuropodia. Notopodia and notochaetae of chaetigers 13 and 16 reduced in size compared to those of chaetigers 4–15. Notochaetae capillary of two types; long ones with numerous short hair on one side from shaft to tip; short ones with numerous short hair subdistally on one side of shaft and pectinated distally ( Fig. 4 B, C). Neuropodia wedge-shaped, erect tori bearing numerous uncini. Uncini with major teeth arranged in four vertical rows, each row with 7–9 teeth ( Fig. 4 D, E).

Scaphe formed by fusion of 5 posterior segments, distinctly separated from abdomen, longer than broad ( Figs 3 B, 4G). Scaphe with crenulated margins ( Figs 3 B, 4G, H). Scaphal hooks 14 pairs, short, pointed, with curved tips ( Fig. 4 I). Anal tongue oval, broader than long with smooth edge. Anal cirrus lacking.

Variation among type specimens. Several morphological parameters show variations among the type specimens ( Table 1 ). The body length and width vary from 4.2 mm to 15.4 mm, and 1.0 mm to 2.3 mm, respectively. The number of cirri on the cephalic veil, the number of pairs of paleae, and the number of scaphal hooks ranges from 10–20, 10–15, and 9–14, respectively. Both body width and body length have significant positive correlation with two other morphological parameters (number of cirri on cephalic veil, number of pairs of paleae), but the correlation coefficient was higher for body width, probably due to more data available ( Table 1 ). Specifically, there was significant linear correlation between the body width (X 1 in mm) or body length (X2) and the number of cirri on the cephalic veil ( Y 1) ( Y 1 = 3.66 X1 + 7.75, r = 0.610, P = 0.0026, n = 22; Y 1 = 0.69 X2 + 8.20, r = 0.592, P = 0.0077, n = 19) or the number of pairs of paleae ( Y 2) ( Y 2 = 1.88 X1 + 8.97, r = 0.606, P = 0.0028, n = 22; Y 2 = 0.28 X2 + 9.87, r = 0.458, P = 0.0497, n = 19). However, there was no significant correlation between the body size and the number of pairs of scaphal hooks ( Y 3) ( Y 3 = 1.37 X1 + 8.15, r = 0.441, P = 0.0588, n = 19; Y 3 = 0.22 X2 + 8.70, r = 0.344, P = 0.1493, n = 19).

Type locality and distribution. Currently only known from the Mai Po Inner Deep Bay Ramsar Site of Hong Kong.

Holotype Paratype n.r. character not recorded due to loss of the posterior part.

Figures

FIGURE 2. Lagis crenulatus sp. nov., tube of holotype IOCAS MBM 119742. Bar scale = 2 mm.

FIGURE 3. Lagis crenulatus sp. nov., drawn from holotype IOCAS MBM 119742. A. lateral view of anterior end. Bar scale = 1 mm. B, lateral view of posterior end. Bar scale = 0.5 mm.

FIGURE 4. Lagis crenulatus sp. nov. Scanning electron micrographs of paratypes IOCAS MBM 119752 (A, G), AM W 38678 (B – F, H) and AM W 38682 (I). A. lateral view of anterior end, showing the absent of branchial and posterior dorsal lobe, Bar scale = 100 µm. B, C. notochaetae from chaetiger 5, Bar scale = 20 µm. D, neurochaetae from chaetiger 8, Bar scale = 20 µm. E, neurochaetae from chaetiger 15, Bar scale = 20 µm. F, some of the scaphal hooks, Bar scale = 20 µm. G. dorsal view of scaphe, Bar scale = 100 µm. H, details of scaphal margin, Bar scale = 100 µm. I. ventral view of scaphe, Bar scale = 100 µm.

Tables

TABLE 1. Major quantitative morphological parameters in Lagis crenulatus.

Catalogue number	Body length (mm)	Anterior body width (mm)	Number of cirri on cephalic veil	Number of pairs of paleae	Number of pairs of scaphal hooks
IOCAS MBM119742	11.8	2.14	14	11	14
IOCAS MBM119743	15.38	2.31	20	14	11
IOCAS MBM119744	9.00	1.91	13	13	10
IOCAS MBM119745	6.83	1.59	14	13	n. r.
IOCAS MBM119746	6.75	1.74	11	12	n. r.
IOCAS MBM119747	4.16	1.56	16	11	n. r.
IOCAS MBM119748	5.53	1.34	12	11	12
IOCAS MBM119749	9.24	1.94	14	10	9
IOCAS MBM119750	6.43	0.98	10	11	10
IOCAS MBM119751	11.58	2.19	16	15	12
IOCAS MBM119752	7.33	1.47	10	13	10
AM W38672	9.86	2.15	18	13	10
AM W38673	5.63	0.88	10	10	8
AM W38674	8.37	2.96	17	15	13
AM W38675	9.64	2.05	14	14	10
AM W38676	8.55	1.75	15	12	10
AM W38677	6.35	1.65	19	13	n. r.
AM W38679	7.85	1.46	14	12	10
AM W38680	8.09	2.08	14	11	9
AM W38681	11.54	1.67	16	13	13
AM W38682	9.40	2.02	13	12	14