Notomastus sunae, Lin & García-Garza & Lyu & Wang, 2020
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https://dx.doi.org/10.3897/zookeys.946.50662 |
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lsid:zoobank.org:pub:F968A6EE-FAA3-4E19-B9FC-FE768C05DD22 |
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https://treatment.plazi.org/id/1E60348C-F682-457C-862C-D7BED5215024 |
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lsid:zoobank.org:act:1E60348C-F682-457C-862C-D7BED5215024 |
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treatment provided by |
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scientific name |
Notomastus sunae |
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sp. nov. |
Notomastus sunae sp. nov. Figures 2A-F View Figure 2 , 3A-F View Figure 3 , 4A-G View Figure 4
Type material examined.
Holotype: TIO-BTS-Poly-114 (sta. XM12)-Xiamen Bay, Fujian Province, [24°33'54"N, 118°10'00"E], 6 m, mud, complete, 25 August 2018, coll. Junhui Lin. Paratypes: TIO-BTS-Poly-115-6 specimens, same information as holotype, one mounted on SEM stub; TIO-BTS-Poly-116 (sta. QPW1-4)-9 specimens, Xiamen Bay, [24°27'16"N, 118°10'20"E], intertidal, muddy sand, 23 January 2019; TIO-BTS-Poly-117-9 specimens, 4 April 2019; TIO-BTS-Poly-118-23 specimens, 24 July 2019; TIO-BTS-Poly-119-4 specimens, 13 September 2019; TIO-BTS-Poly-120-16 specimens, 30 October 2019. Specimens (from TIO-BTS-Poly-116 to TIO-BTS-Poly-120) collected from the identical site (QPW1-4) by Junhui Lin.
Additional material examined.
TIO-BTS-Poly-121 (sta. XHW04)-3 specimens, Xinghua Bay (Fujian Province), [25°25'55"N, 119°24'16"E], 7 m, mud, 17 April 2019, coll. Zhong Li; TIO-BTS-Poly-122 (sta. DS06)-1 specimen, Dongshan Bay (Fujian Province), [23°48'57"N, 117°31'41"E], 5 m, mud, 26 February 2019, coll. Heshan Lin; TIO-BTS-Poly-123-2 specimens, same location as TIO-BTS-Poly-122, 17 June 2019, coll. Heshan Lin; TIO-BTS-Poly-124-6 specimens, Jieshi Bay (Guangdong Province), [22°45'22"N, 115°47'09"E], 8 m, mud, 19 August 2019, coll. Zhizhong Huang; TIO-BTS-Poly-125-2 specimens, [22°42'40"N, 115°48'10"E], 21 m, muddy sand, 19 August 2019, coll. Zhizhong Huang; TIO-BTS-Poly-126-1 specimen, Daya Bay (Guangdong Province), [22°34'42"N, 114°33'30"E], 12.5 m, mud, 20 February 2016, coll. Junhui Lin; TIO-BTS-Poly-127-2 specimens, outside Pearl River estuary (Guangdong Province), [21°54'49"N, 113°42'15"E], 23 m, muddy sand, 24 October 2019, coll. Zhizhong Huang; TIO-BTS-Poly-128 (sta. GFC-S23)-4 specimens, Qinzhou Bay (Guangxi Province), [21°35'04"N, 108°32'07"E], 7 m, muddy sand, 28 October 2017, coll. Zhong Li; TIO-BTS-Poly-129 (sta. GFC-S11)-1 specimen, [21°37'34"N, 108°38'15"E], 9.5 m, muddy sand, 20 April 2018, coll. Zhong Li; TIO-BTS-Poly-130 (sta. GFC-S23)-1 specimen, same location as TIO-BTS-Poly-128, 19 April 2018, coll. Zhong Li; TIO-BTS-Poly-131 (sta. GFC-S33)-1 specimen, [21°34'31"N, 108°52'42"E], 7 m, muddy sand, 21 April 2018, coll. Zhong Li; TIO-BTS-Poly-132 (sta. GFC-S02)-2 specimens, [21°37'32"N, 108°34'57"E], 12 m, mud, 17 August 2018, coll. Zhong Li; TIO-BTS-Poly-133 (sta. GFC-S19)-2 specimens, [21°31'55"N, 108°34'29"E], 12 m, sand with shell fragment, 17 August 2018, coll. Zhong Li; TIO-BTS-Poly-134 (sta. GFC-S48)-1 specimen, [21°39'29"N, 108°36'47"E], 14 m, mud, 17 August 2018, coll. Zhong Li; TIO-BTS-Poly-135 (sta. CJ03)-2 specimens, off western Hainan Island, [19°27'56"N, 108°49'40"E], 20 m, muddy sand, 22 May 2019, coll. Zhong Li; TIO-BTS-Poly-136 (sta. CJ07)-2 specimens, [19°29'46"N, 108°50'24"E], 18 m, muddy sand, 22 May 2019, coll. Zhong Li.
Comparative type material.
Notomastus hemipodus Hartman, 1945, holotype: LACM-AHF Poly-414-North Carolina, Bogue Sound, dredged in a few feet of water, 15 June 1940; paratypes: LACM-AHF Poly-415-North Carolina, Bogue Sound, June 1940; LACM-AHF Poly 2667-muddy sand at low tide, June 1940; LACM-AHF Poly 2668-incomplete, muddy sand flats at low water, June 1940; LACM-AHF Poly-2669-incomplete, outer end of Bird Shoal, 18 June 1940, coll. O. Hartman. Notomastus americanus Day, 1973, Holotype: USNM 43118-North Carolina, Beaufort, 4 June 1965; Paratype: USNM 43119-North Carolina, Beaufort, 4 June 1965 coll. J. Day.
Sequence.
MT055861 (18S, 1637 bp), MT055862 (H3, 316 bp), MT055863 (COⅠ, 650 bp), determined from paratype (TIO-BTS-Poly-118).
Description.
Holotype complete with over 100 chaetigers (Fig. 3A View Figure 3 ), measuring 33.74 mm long by 0.8 mm wide. Paratypes complete or incomplete, ranging from 6.81-43.02 mm long, 0.57-0.90 mm wide for 19-103 chaetigers. Color in alcohol tan (Fig. 3B View Figure 3 ). Thorax dorsally rounded, ventrally flattened, widest at chaetiger 3. Prostomium conical, with narrow palpode (Figs 2A-C View Figure 2 , 3B View Figure 3 , 4A, B View Figure 4 ). Everted proboscis globular, with numerous minute papillae (Fig. 2A-C View Figure 2 ). Eyespots present on lateral sides of prostomium (Figs 2A, C View Figure 2 , 3B View Figure 3 ). Peristomium achaetous, wider than long, as wide as first chaetiger, but longer (Fig. 2A View Figure 2 ). Thorax slightly areolated in anterior 4-5 chaetigers, remaining chaetigers smooth.
Thorax consisted of an achaetous peristomium and 11 chaetigers (Fig. 2A, B View Figure 2 ). Chaetiger 1 uniramous (Figs 2A, C View Figure 2 , 4A, B View Figure 4 ), with capillaries in notopodia only. Chaetigers 2-10 with only capillaries in both rami (Figs 2A, B View Figure 2 , 4A, D View Figure 4 ). All capillaries bilimbate. Chaetiger 11 transitional with notopodial capillaries and neuropodial hooded hooks (Figs 2A, D View Figure 2 , 4A, C View Figure 4 ). Chaetigers 1-4 slightly expanded. Chaetigers 6-10 biannulated with intra- and inter-segmental grooves (more evident in lateral view), wider than long (Fig. 2A, B View Figure 2 ). Notopodia inserted dorsolaterally in first five thoracic chaetgiers, then notopodia inserted dorsally from chaetiger 6 to posterior thorax (Fig. 2B View Figure 2 ). Neuropodia ventrolateral. Chaetal fascicles inserted just posterior to midline of thoracic segments (Figs 2A, B View Figure 2 , 4A View Figure 4 ). Notopodia of chaetigers 1-11 and neuropodia of chaetigers 2-10 each with 10-25 capillaries per fascicle; neuropodia of chaetigers 11 with approximately 16 hooks per fascicle. Thoracic hooks of similar shape to abdominal hooks, but shaft markedly longer. Lateral organs conspicuous in thorax and anterior abdomen, located between noto- and neuropodia, closer to notopodia, as small rounded pores (Fig. 2A-C View Figure 2 ). Genital pores present on intersegmental grooves of between chaetigers 7/8, 8/9, 9/10, and 10/11 on holotype.
Transition between thorax and abdomen marked by change in chaetal arrangement and methyl green staining pattern (Figs 2A, B, D View Figure 2 , 3C, D View Figure 3 , 4A View Figure 4 ). First abdominal segment as wide as last thoracic chaetiger, but slightly shorter (Fig. 2A, B View Figure 2 , 3C, D View Figure 3 ). Parapodial lobes reduced in anterior abdomen, well separated (Fig. 2A, B View Figure 2 ). Notopodial lobes located dorsally (Fig. 2B View Figure 2 ), close together in anterior abdomen, becoming dorsolateral in posterior abdomen. Neuropodial lobes lateral, separated ventrally. Chaetal fascicles positioned posterior to midsegment in anterior abdomen (Fig. 2B, D View Figure 2 ), and near posterior edge of segment toward the pygidium (Fig. 2E View Figure 2 ). In the far posterior, notopodial lobes with a simple epithelial extension (Figs 2E View Figure 2 , 3E View Figure 3 ), broadly-based and rounded-tipped. In anterior abdomen, chaetal fascicles with approximately 10 hooks in notopodia and 16 hooks in neuropodia, decreasing to 6 hooks in notopodia and 10 hooks in neuropodia in posterior abdomen, and to 1-2 hooks in segments near pygidium. Notopodial and neuropodial abdominal hooded hooks of similar shape, with angled node, evident constriction, developed shoulder, posterior shaft longer than anterior one, attenuated to terminal end (Fig. 2F View Figure 2 ). Hood smooth, slightly longer than wide (Fig. 2F View Figure 2 ). Abdominal hooded hooks (Fig. 4E-G View Figure 4 ) with multiple rows of teeth above main fang: 4-5 teeth in basal row, 6-8 teeth in second row, and at least 6 teeth in superior row.
No branchiae observed in abdomen. Regenerated pygidium simple, without anal cirri (Fig. 3E, F View Figure 3 )
Methyl green staining pattern
(Figs 2B, D View Figure 2 , 3A, C, D View Figure 3 ). Thorax stained with blue with slightly different intensity whereas abdomen stained with very dark blue. From postchaetal area of chaetiger 12, abdominal segments dorsally stained with dark blue, extending ventrallaterally, interrupted by parapodial lobes and lateral organs. Toward posterior abdomen, blue stain on abdominal dorsum faded gradually. From chaetiger 13, abdominal segments with paired stripes of ventral stain with darker intensity, interrupted by intersegmental rings.
Distribution.
The new species is widely distributed along the southern coasts of China, from Fujian Province westward to Guangxi Province, and southward to Hainan Province (Fig. 1 View Figure 1 ).
Ecology.
The examined specimens were collected from intertidal to shallow subtidal coastal waters (~23 m). Sediment was mainly characterized by mud or muddy sand. The new species is especially abundant in nearshore waters off eastern Xiamen Island, Fujian Province.
Etymology.
The species is named after Professor Ruiping Sun, in recognition of her contribution to the study of polychaetes from China Seas.
Variation.
Eyespots on prostomium were indistinct in several specimens due to preservation in alcohol. MGSP on chaetigers 11-12 may be different among individuals. Some specimens have darker stain on post-chaetal area of chaetiger 11.
Remarks.
As the most species-rich genus of Capitellidae , Notomastus has more morphological variability, including variation in the structure of the last thoracic chaetigers. Although it is known that hooks may be replaced by capillaries in the middle-posterior thorax of capitellids during ontogeny ( Blake 2000), such as the example of Heteromastus (Warren and Hutchings 1994), several authors have confirmed the presence of neuropodial hooks in posterior thorax of some Notomastus species even when in adulthood ( Ewing 1982; Blake 2000; Green 2002, Magalhães and Blake 2017). For instance, among the 44 examined specimens of N. angelicae , Hernández-Alcántara and Solís-Weiss (1998) found that 43 specimens possessed only hooks in the neuropodium of chaetiger 11. Nevertheless, less efforts have been devoted to detecting whether this character change during the development of the specimens. In this study, Notomastus sunae sp. nov. specimens were collected from the identical site (sta. QPW1-4) in different months (January, April, July, September, and October). All the 61 specimens uniformly have the last thoracic chaetiger (chaetiger 11) transitional with notopodial capillaries and neuropodial hooded hooks, regardless of body size. Additional specimens from other localities also confirm the similar chaetal structure of chaetiger 11 to the type material. These indicate the stability of this character and that it could be used as an identification tool at the species level.
Notomastus sunae sp. nov. is readily distinguished from most congeners by the presence of neuropodial hooks in last thoracic chaetiger. Among the known Notomastus species with neuropodial hooks in chaetiger 11, N. sunae sp. nov. closely resembles N. mossambicus by the presence of uniramous chaetiger 1 and prostomial eyespots, but differs from the latter in that the new species has prostomial palpode and slightly areolated epithelium in anterior thorax, whereas N. mossambicus has prostomium without palpode and strongly areolated epithelium in anterior thorax as stated by Thomassin (1970) and Cinar (2005). The new species differs from the geographically close Korean species Notomastus koreanus described by Jeong et al. (2018) in that the new species bears eyespots on prostomium, reduced parapodial lobes in anterior abdomen, as well as neuropodial hooks in the last thoracic chaetiger. In terms of the MGSP, N. sunae sp. nov. has paired stripes of ventral stain, the feature shared by N. hemipodus and N. koreanus . However, N. sunae sp. nov. has very dark blue stain on abdominal dorsum and extending dorsolaterally, which is distinct from other Notomastus species.
Based on morphological description and illustration provided by Green (2002), a Notomastus species (labelled as N. near hemipodus ) reported from Andaman Sea is closely similar to N. sunae sp. nov. in a number of characters: presence of palpode and eyespots on prostomium, uniramous chaetiger 1, slightly areolated epithelium on anterior 4-5 chaetigers, and the MGSP on abdomen which has very dark blue stain on dorsum and paired stripes of ventral stain. Green (2002) mentioned that some specimens had chaetiger 11 transitional with notopodial capillaries and neuropodial hooks, which also agreed with N. sunae sp. nov. As the specimens examined by Green (2002) only had anterior fragments (23-37 chaetigers) and lacked ultrastructure of hooded hooks and gene sequences, further comparison is hindered. According to the redescription of N. hemipodus by García-Garza et al. (2012), the specimens identified as N. near hemipodus could not belong to N. hemipodus in that: 1) they had slightly areolated epithelium on anterior thorax instead of strongly tessellated epithelium as in N. hemipodus ; 2) they had reduced neuropodial lobes in the anterior abdomen instead of expanded neuropodial lobes as in N. hemipodus ; 3) they had very dark blue stain on abdominal dorsum instead of moderate green stain as in N. hemipodus .
Notomastus sunae sp. nov. is commonly collected and abundant in Xiamen Bay, Fujian Province, widely distributed westward to Qinzhou Bay, Guangxi Province, and southward to western Hainan Island, based on the examined material obtained from several localities along southern China. Its specimens are found in great geographical ranges at latitude from 19.5N to 25.5N and at longitude from 108.8E to 119.5E. They prefer to inhabit soft sediments, like mud or muddy sand. So far, this species is found in shallow coastal waters less than 30 m deep.
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.
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