Amphicteis hwanghaiensis, Wang & Sui & Li & Hutchings & Nogueira, 2020
|
publication ID |
https://dx.doi.org/10.3897/zookeys.988.49934 |
|
publication LSID |
lsid:zoobank.org:pub:EF36701A-F13A-44E6-A29C-45BE084DCA3A |
|
persistent identifier |
https://treatment.plazi.org/id/9AF8951F-61CE-406C-982F-9095865B8D04 |
|
taxon LSID |
lsid:zoobank.org:act:9AF8951F-61CE-406C-982F-9095865B8D04 |
|
treatment provided by |
|
|
scientific name |
Amphicteis hwanghaiensis |
| status |
sp. nov. |
Amphicteis hwanghaiensis sp. nov. Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4
Material examined.
Type material. Yellow Sea, China (33°58.45'N, 123°57.02'E; 77 m deep), subtidal in mud, collected 28 November 2019. Holotype: MBM286623; Paratype: MBM286624, 1 specimen.
Description.
Holotype Complete, length 27.8 mm, thoracic width 5.5 mm. Dorsum of thoracic segments and branchiae with red pigmentation (Fig. 1A, D View Figure 1 ). Thorax and abdomen well defined; thorax approximately twice as wide and long as abdomen; barely tapering towards posterior part. Prostomium with middle lobe as paired longitudinal glandular ridges, slightly diverging distally, V-shaped, gap between glandular ridges absent (Fig. 2A View Figure 2 ); eyespots absent. Nuchal organs as paired nuchal ridges separated by a small median gap, V-shaped (Fig. 2A View Figure 2 ). Segment I inconspicuous, barely visible laterally, in superior view. Segment II developed ventrally and laterally, bearing paleae, covered by branchiae dorsally (Figs 1A-E View Figure 1 , 2A, B View Figure 2 ). Four pairs of long and tapering branchiae, in 2 transverse rows on segments III and IV, separated by a mid-dorsal rectangular hump of half inner branchiae width (Figs 1A, D View Figure 1 , 2B View Figure 2 ); inner branchiae 2 times thicker than outer ones; innermost branchiae of anterior transverse row originating from segment II, outermost branchiae of anterior transverse row originating from segment III, innermost branchiae of posterior transverse row originating from segment IV, outermost branchiae of posterior transverse row originating from segment V (Fig. 2B View Figure 2 ). Left and right groups of golden paleae present on segment II with 11 on right side and 13 on left side (Figs 1A-E View Figure 1 , 2A View Figure 2 ). Paleae arranged in shallow arcs with the longest paleae innermost; stout and slightly curved dorsally and tapering to short blunt tips; well developed, twice as long as prostomium (Figs 1A-E View Figure 1 , 2A, C View Figure 2 , 3C View Figure 3 ). Notopodia with capillary chaetae and tuberculate ventral cirrus from segment III, present on 17 chaetigers (Figs 1F View Figure 1 , 2B, D, E View Figure 2 , 3A, B View Figure 3 ); anterior notopodia small, increasing in size from first to fourth pair (Fig. 1A-C View Figure 1 ). Neuropodial tori with uncini from segment VI, present on 14 thoracic uncinigers; tori without offset dorsal lobe (Figs 1F View Figure 1 , 2D View Figure 2 ). Continuous ventral shields present to approximately thoracic unciniger 12. Elevated or modified notopodia absent. Intermediate uncinigers absent. Fifteen abdominal uncinigers with digitiform rudimentary notopodia (Figs 1G View Figure 1 , 2F View Figure 2 ). Pinnules with tiny tuberculate dorsal cirrus (Figs 1G View Figure 1 , 2F View Figure 2 ). Thoracic and abdominal uncini arranged in single vertical rows with subrostral process and five or six teeth in a single row over basal prow (Figs 2G, H View Figure 2 , 3D, E View Figure 3 ). Pygidium with terminal anus and two laterally attached tapering anal cirri, approximately as long as the last five chaetigers (Fig. 1H View Figure 1 ).
Paratype complete, 31 mm long, 4.5 mm wide, with ten paleae on right side and eight on left (Fig. 4A, B View Figure 4 ). Eighteen thoracic chaetigers one side and 17 thoracic chaetigers on the other side (Fig. 4C View Figure 4 ). Dorsum of thoracic segments shows no pigmentation and only inner branchiae have several red bands.
Etymology.
The species is named after its type locality in the Yellow Sea of China. The species name is an adjective in the nominative singular, derived from “hwanghai” which means "Yellow Sea" in Chinese, with the Latin suffix -ensis to denote a place.
Distribution.
Yellow Sea at 79 m depth.
Remarks.
The presence of stout paleae with blunt tips is characteristic for A. hwanghaiensis sp. nov.. Schiaparelli and Jirkov (2016) provided a revision of the genus Amphicteis and concluded that out of the 38 Amphicteis species (known at that time), only five species have this type of paleae: A. mederi , A. midas (Gosse, 1855), A. taurus Reuscher, Fiege & Imajima, 2015, A. ninonae Jirkov, 1985, and A. teresae Schiaparelli & Jirkov, 2016. According to Reuscher et al. (2015), A. dalmatica Hutchings & Rainer, 1979 and A. philippinarum Grube, 1878 also have short and poorly developed paleae. The latter species differs from A. hwanghaiensis sp. nov. by having foliose branchiae and uncini without a subrostral process, while A. hwanghaiensis sp. nov. only have cirriform branchiae and uncini with a subrostral process. To make clear the distinction between members of A. dalmatica and our new species, the type material of A. dalmatica was examined, redescribed, and compared with the new species (below).
All the other Amphicteis species have paleae with fine filamentous tips; the difference between fine-tipped and stout-tipped paleae is easy to distinguish. According to Schiaparelli and Jirkov (2016), the shape of blunt, stout paleae from the five known species belonging to this group are all very similar, but there are other diagnostic morphological differences, which can be used to distinguish them from the new species.The difference between A. mederi and A. hwanghaiensis sp. nov. is that A. mederi has abdominal pinnules with a cirriform dorsal cirrus, while the new species has a tuberculate dorsal cirrus; the thoracic and abdominal uncini of A. hwanghaiensis sp. nov. have five or six teeth in a single row over the basal prow while the uncini in A. mederi have six teeth ( Annenkova 1929; Uschakov 1955). According to Schiaparelli and Jirkov (2016), who checked the holotype of A. mederi , the prostomial glandular ridges of A. mederi are separated by a wide median gap equal to the width of the ridge, while a gap between glandular ridges is absent in A. hwanghaiensis sp. nov. (Fig. 2A View Figure 2 ).
A comparison of A. midas and A. hwanghaiensis sp. nov. shows differences in the rounded spots on the anterior dorsum and the dark transversal pigment bands on its branchiae ( Schiaparelli and Jirkov 2016); in contrast, the new species has red pigmentation on its branchiae. In addition, the area between the branchial groups is very different. Amphicteis hwanghaiensis sp. nov. has a narrow mid-dorsal rectangular hump between the inner branchiae while the area between the branchial groups of A. midas is flat and unmodified ( Hartley 1985).
Amphicteis taurus is clearly distinct and differs from A. hwanghaiensis sp. nov. in the following features. The paleae of A. taurus are unique in the genus Amphicteis , being strongly enlarged, nearly straight with a uniform thickness over the entire length, and tips rounded, at about a 45-degree angle to the body. Amphicteis taurus is also different from A. hwanghaiensis sp. nov. by the smaller prostomial glandular ridges and the wide gap separating them. Other differences between them are the longer, annulated cephalic region (peristomium and possibly segment I) of A. taurus and the shorter cephalic region of the new species ( Reuscher et al. 2015).
According to original description, A. teresae has a larger number of paleal chaetae (15-17 on each side). Amphicteis hwanghaiensis sp. nov. has a lower lip with a narrow, distinct, and white middle transversal band which is absent in A. teresae . Uncini of A. hwanghaiensis sp. nov. have five or six teeth besides the subrostral tooth, while uncini of A. teresae usually have five. As for eyespots, which are absent in new species, Schiaparelli and Jirkov (2016: 541) said that "Another clear character of Amphicteis teresae sp. n. that distinguishes it from the other related ones having blunt paleal chaetae is the presence of an eyespot". Furthermore, A. teresae is found in Antarctica.
Amphicteis ninonae , recorded from Norwegian Sea and Arctic Seas, is most similar to the new species; however, members of this species are distinguished because, according to Jirkov (1985), the paleae are dark brown, while those of A. hwanghaiensis sp. nov. are golden. Amphicteis hwanghaiensis sp. nov. also has a narrow rectangular hump between the branchial groups, while the area between the branchial groups of A. ninonae is flat and unmodified. Parapar et al. (2011) also suggested that A. ninonae seems to be restricted to the north and east coasts of Iceland.
Four species of Amphicteis , A. glabra , A. gunneri , A. scaphobranchiata , and A. chinensis , have been recorded from Chinese seas, according to Sui and Li (2017). The new species differs from these species by having blunt and stout tipped paleae, as these four species belong to the group of Amphicteis species with tips of paleae sharply tapering into fine filaments.
Among the species from the Western Pacific, specimens belonging to Amphicteis malayensis Caullery, 1944 differ from those of A. hwanghaiensis sp. nov. by the possession of prostomial eyespots and a wide median gap between glandular ridges. Members of A. theeli Caullery, 1944 and A. quadridentata Caullery, 1944 have 14 and 16 abdominal uncinigers, respectively. The branchiae of individuals of A. spinosa Reuscher, Fiege & Imajima, 2015 have four rows of pointed protuberances, while branchiae are smooth among specimens belonging to our new species. Finally, specimens belonging to A. uncopalea Chamberlin, 1919, found in the North-western Pacific, have well-developed paleae with curly and fine tips, and a distinct rounded lobe behind the paleae originating from segment III.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.