Scolelepis (Scolelepis) daphoinos, Zhou, Jin, Ji, Weiwei & Li, Xinzheng, 2009

Zhou, Jin, Ji, Weiwei & Li, Xinzheng, 2009, A new species of Scolelepis (Polychaeta: Spionidae) from sandy beaches in China, with a review of Chinese Scolelepis species, Zootaxa 2236, pp. 37-49 : 39-41

Scolelepis (Scolelepis) daphoinos sp. nov.

Figure 1

Scolelepis (Scolelepis) squamata ( Müller, 1806) , Yang & Sun 1988: 216, fig. 97 E–G.

Type material. Holotype: MBMCAS 228838, tidal flat of Kongdong Is., Shandong Province, 19°30΄ N, 107°30΄ E, sandy mud, 20 Apr 2007, coll. Hongfa Wang. Paratypes: MBMCAS 228828 (5 spms), tidal flat of Zhanggong Is., Shangdong Province, sandy mud, 20 Apr 2007, coll. Hongfa Wang; MBMCAS 228829 (28 spms), tidal flat of Rushan City, Shandong Province, 121°37΄ N, 36°44΄ E, silty sand, 20 May 2007, coll. Hongfa Wang; MBMCAS 228831 (3 spms), tidal flat of Rushan City, Shandong Province, 121°29΄ N, 36°46΄ E, silty sand, 20 May 2007, coll. Jin Zhou; MBMCAS 228832 (11 spms), low tidal flat of Rushan City, Shandong Province, 121°29΄ N, 36°46΄ E, silty sand, 20 May 2007; MBMCAS 228833 (3 spms), middle tidal flat of Rushan City, Shandong Province, 121°37΄ N, 36°44΄ E, silty sand, 12 Aug 2007; MBMCAS 228834 (210 spms), middle tidal flat of Rushan City, Shandong Province, 121°37΄ N, 36°44΄ E, silty sand, 5 Nov. 2007; MBMCAS 228835 (10 spms), low tidal flat of Rushan City, Shandong Province, 121°37΄ N, 36°44΄ E, silty sand, 5 Nov 2007; MBMCAS 228836 (80 spms), middle tidal flat of Rushan City, Shandong Province, 121°29΄ N, 36°46΄ E, silty sand, 20 May 2007; MBMCAS 228837 (88 spms), low tidal flat of Rushan City, Shandong Province, 121°29΄ N, 36°46΄ E, silty sand, 5 Nov 2007; MBMCAS 228839 (4 spms), low tidal flat of Liugong Is., Shandong Province, 14 Apr 2007; MBMCAS 228840 (7 spms), middle tidal flat of Liugong Is., Shandong Province, 19 Apr 2007; MBMCAS 228841(1 spm), low tidal flat of Yangma Is., Shandong Province, 22 Apr 2007; MBMCAS 228842 (2 spms), middle tidal flat of Yangma Is., Shandong Province, 23 Apr 2007; MBMCAS 228894 (4 spms), tidal flat of Huiquan Bay, Qingdao City, silty sand, 23 May 1963, coll. Daoyuan Sun & Mu Chen.

Other material examined. MBMCAS 198576 (4 spms), tidal flat of Huiquan Bay, silty sand, 23 May 1963, coll. Mu Chen & Ruiping Sun; MBMCAS 198577 (5 spms), tidal flat of Laohushi, Hebei Province, 20 Apr 1978; MBMCAS 198578 (7 spms), high tidal flat of Huiquan Bay, Qingdao City, 23 May 1963, coll. Ruiping Sun & Mu Chen; MBMCAS 198579 (1 spm), Zhanqiao pear, Qingdao City, Shandong Province (trawl), 24 Apr 1963; MBMCAS 198580 (20+ spms), tidal flat of Huiquan Bay, Qingdao City, 6 Jun 1963, coll. Mu Chen & Ruiping Sun; MBMCAS 198581 (8 spms), tidal flat of Yantai City, Shandong Province, sand, 20 Jun 1963; MBMCAS 198582 (6 spms), tidal flat of Huiquan Bay, Qingdao City, 6 Jun 1963; MBMCAS 198583 (5 spms), tidal flat of Yantai City, Shandong Province, 21 Jun 1963; MBMCAS 198584 (3 spms), middle tidal flat of Zhifu district, Yantai City, Shandong Province, 20 Jun 1963; MBMCAS 198586 (10+ spms), tidal flat of Huiquan Bay, 28 Aug 1963; MBMCAS 198587 (4 spms), tidal flat of Taiping Bay, Qingdao City, 5 May 1958; MBMCAS 198588 (6 spms), tidal flat of Huiquan Bay, Qingdao City, 9 Jun 1963; MBMCAS 198594 (13 spms), tidal flat of Maidao Is., Qingdao City, sand, 29 May 1957, coll. Uschakov; MBMCAS 198594 (7 spms), tidal flat of Zhifu district, Yantai, Shandong Province, 28 Jun 1957, coll. Strelkov & Uschakov; MBMCAS 198595 (50+ spms), tidal flat of Taiping Bay and Huiquan Bay, Qingdao City, silty sand, 28 Aug 1963; MBMCAS 198717 (3 spms), tidal flat of Huangdao Is., Qingdao City, 12 Sep 1957; MBMCAS 228676 (2 spms), tidal flat of Yantai Mountain, 21 Jun 1963.

Description of holotype. Specimen complete, 0.8 mm wide and 12 mm long for 92 setigers. Color in alcohol yellowish. Body wide anteriorly, tapering posteriorly. Prostomium elongated, with pointed anterior margin. Caruncle extending posteriorly to setiger 1, terminating with distinct protuberance. Distinct reddish patches present in posterior part of prostomium. Occipital tentacle absent. Two pairs of eyes, arranged in a transverse row. Peristomium long, distinct from setiger 1, forming well-developed lateral wings ( Fig. 1 A–B). Proboscis not observed. Palps missing.

Distinct reddish patches present on sides and dorsal surface of anterior setigers. Parapodia of setiger 1 well developed; notopodial postsetal lamellae triangular and neuropodial postsetal lamellae subtriangular, with capillary setae in both rami ( Fig. 1 C). Branchiae present from setiger 2, continuing posteriorly to end of body. Notopodial postsetal lamellae fused with branchiae along about 90% of length, long, narrow with slight ruffled edge in anterior setigers ( Fig. 1 D–F). Posterior notopodial lamellae triangular with elongated pointed tips ( Fig. 1 G). Degree of fusion with branchiae decreasing in posterior setigers. Neuropodial postsetal lamellae oval on setigers 2–3, rounded on following setigers; becoming low and round from around setiger 30 to posterior setigers. Notch present from setiger 31, dividing lamellae into two lobes from setiger 49. On following setigers lamellae divided into subtriangular interramal lobe and small low, rounded ventral lobe ( Fig. 1 G). Neuropodial presetal lamellae thick and round, from setiger 2 to posterior setigers; smaller than corresponding neuropodial postsetal lamellae.

All anterior setae sheathed capillaries, arranged in two rows on both rami; anterior row thick, heavily granulated, with obvious sheaths, posterior row thin with narrow sheaths ( Fig. 1 H–K). Neuropodial hooded hooks from setiger 39, bidentate, with open hoods ( Fig. 1 L), 6–12 in a series, accompanied by capillaries. Notopodial hooded hooks present from setiger 60, bidentate, with open hoods ( Fig. 1 M), 2–4 in a series, accompanied by capillaries.

Pygidium cushion-like, without lateral anal cirri, anus opening dorsally ( Fig. 1 N).

Variability. Paratypes 5.4–26 mm long (mean length: 12.217 ±5.65, n=456) and 0.5–2.3 mm wide for 48– 101 setigers. Palps relatively short in this species (usually reaching to not more than setiger 3). Palps slender, with basal sheath, but lacking cilia at bases of sheaths ( Fig. 1 O). Eyes arranged in a transverse row or in trapezoid; lateral eyes kidney-shaped and inner ones rounded. All specimens with neuropodial lamellae rounded on anterior setigers, developing notch around setigers 26–35. Notch becoming deeper, dividing lamellae into separate lobes around setigers 34–50, on posterior setigers dorsal neuropodial lamellae square with triangular dorsal projection. Neuropodial hooded hooks present from setigers 32–41, numbering 2–9 in a series. Notopodial hooded hooks from setiger 48–63, 2– 6 in a series. All specimens having bidentate hooded hooks only.

Distinct reddish pigment patches on sides of body easily faded after preservation in ethanol; however, those on dorsal surface usually well preserved even after a long time of fixation (more than 35 years).

Etymology. From the Latin daphoinos , referring to the obvious reddish patches on the posterior part of the prostomium and on the sides and dorsal surface of the body.

Remarks. Scolelepis (Scolelepis) daphoinos sp. nov. is frequently encountered and highly abundant on sandy beaches in northern Chinese waters; however, it has long been misidentified as S. (S.) squamata ( Müller, 1806) (e.g., Yang & Sun 1988; Sun 1990). These two species are similar in the morphology of the prostomium and parapodia, but differ in that S. (S.) daphoinos sp. nov. bears bidentate hooded hooks only rather than having both unidentate and bidentate hooded hooks as in S. (S.) squamata . The more important point is that the new species has distinct reddish pigment patches on the posterior part of the prostomium and on the sides and dorsal surface of the anterior body region. Pigmentation on the prostomium and the sides of the body is easily faded while that on the dorsal surface of the body can be well preserved and easily detected even after a long time of fixation (in some specimens, more than 35 years).

Scolelepis (S.) daphoinos sp. nov. also resembles S. (S.) kudenovi Hartmann-Schröder, 1981 from Australia in having only bidentate hooded hooks in the posterior parapodia. However, the new species has relative short palps (commonly not beyond setiger 3) instead of long palps (extending posteriorly to setiger 10) and reddish pigment patches on the anterior body. In addition, S. (S.) daphoinos sp. nov. mainly inhabits intertidal areas, while S. (S.) kudenovi Hartmann-Schröder, 1981 is mainly distributed in subtidal waters. Distribution. Common on sandy beaches or rarely in the shallow subtidal (<8 m) of the Yellow Sea.

Figures

FIGURE 1. Scolelepis (Scolelepis) daphoinos sp. nov. A, anterior end, dorsal view; B, anterior end, lateral view; C, parapodia of setiger 1, anterior view; D, parapodia of setiger 2, anterior view; E, parapodia of setiger 3, anterior view; F, parapodia of setiger 4, anterior view; G, parapodia of setiger 49, anterior view; H, notopodial seta from anterior row of setiger 4; I, notopodial seta from posterior row of setiger 4; J, neuropodial seta from anterior row of setiger 4; K, neuropodial seta from posterior row of setiger 4; L, neuropodial hooded hook from setiger 32; M, notopodial hooded hook from setiger 32; N, pygidium, dorsal view. O, anterior end, dorsal view (Paratype, MBMCAS 228841). Scales: A, 600 μm; B, O, 400 μm; C – G, 120 μm; H – M, 250 μm; N, 100 μm.