Pseudonereis trimaculata Horst, 1924

Hsueh, Pan-Wen, 2021, New species and record of Pseudonereis (Annelida, Polychaeta, Nereididae) from Taiwan, Zootaxa 4996 (3), pp. 492-512 : 502-507

publication ID	https://doi.org/ 10.11646/zootaxa.4996.3.4
publication LSID	lsid:zoobank.org:pub:50282C10-075C-4B2C-B61C-3A772D5BC2F2
persistent identifier	https://treatment.plazi.org/id/03E587C6-FFA9-FF88-85A0-FB9BFAD4F71D
treatment provided by	Plazi
scientific name	Pseudonereis trimaculata Horst, 1924
status

Treatment

Pseudonereis trimaculata Horst, 1924 View in CoL

Figs 8A–F View FIGURE 8 , 9A–F View FIGURE 9 , 10A–E View FIGURE 10 , 11A–C View FIGURE 11 , 12A–F View FIGURE 12 , 13A–F View FIGURE 13 , 14A–F View FIGURE 14

Nereis (Pseudonereis) trimaculata Horst 1924: 187–188 View in CoL , pl. XXXVI, figs 8, 9. — Hartman 1959: 279.

Pseudonereis rottnestiana View in CoL forma costatodentata Hartmann-Schröder 1979: 119, figs 220–222.

Pseudonereis trimaculata Bakken 2007: 166–168 View in CoL , fig. 13A–I.

Material examined. Atoke: 1 specimen ( NMNS 8383-26 View Materials ), Oldman Rock (22°0.3'N 121°34.7'E), Lanyu Island , Taitung County, Taiwan, rocky intertidal habitats, 3 June 2006 GoogleMaps ; 2 specimens ( NMNS 8383-27 View Materials ), Jihuei (23°6.97'N 121°24.31'E), Taitung County, Taiwan, rocky intertidal habitats, 14 October 2007 GoogleMaps ; 1 specimen ( NMNS 8383-28 View Materials ), Jihuei , Taitung County, 9 October 2010 ; 1 specimen ( NMNS 8383-29 View Materials ), Jihuei , Taitung County, 27 March 2014 ; 7 specimens ( NMNS 8383-28 View Materials – 30 View Materials ), Jihuei , Taitung County, 27 September 2014 ; 1 specimen ( NMNS 8383-31 View Materials ), Ji- huei, Taitung County, 29 April 2017 ; 5 specimens ( NMNS 8383-32 View Materials ), Jihuei , Taitung County, 17 November 2019 ; 5 specimens ( NMNS 8383-33 View Materials ), Kentin (( 20°54.7'N 121°50.8'E), Pingtung County, Taiwan, rocky intertidal habitats, 17 October 2020 GoogleMaps . Epitoke: 2 specimens ( NMNS 8383-34 View Materials ), Jihuei (23°6.97'N 121°24.31'E), Taitung County, rocky intertidal habitats, 17 November 2019 GoogleMaps .

Description. Atoke: Based on specimen NMNS 8383-29, complete, body length 35.5 mm with 83 chaetigers, chaetiger 10 width 1.5 mm, excluding parapodia; beige in alcohol ( Fig. 8A View FIGURE 8 ). Specimens NMNS 8383-26–27, 33 with pharynx everted and used for illustrating paragnath patterns and shape of ridge pattern in Areas VI–V–VI of the pharynx.

Prostomium wider than long, lateral antennae antero-lateral, longer than palps, palpophores globose, palpostyles conical. Four pairs of tentacular cirri, longest one reaching chaetiger 4. Two pairs of eyes, in trapezoidal arrangement, subequal in size. Apodous anterior segment about 1.4 times longer than chaetiger 1. Pharynx with light brown jaws, each with 6 teeth; paragnath pattern: I=1; II=40 (left), 38 (right), in 4 comb-like rows; III=60, in 4 transverse comb-like rows; IV=78 (left), 72 (right), in 5 comb-like rows with additional cones and p-bars in sigmoid towards the jaws; V=3, in triangle; VI=1 (left), 1 (right), shield-shaped bars; VII–VIII=24, p-bars and cones interspaced, p-bar row slightly behind cone row, one paragnath on each furrow and ridge regions ( Fig. 8B–F View FIGURE 8 ). Ridge pattern of areas VI–V–VI, υ-shaped ( Fig. 8B, D–E View FIGURE 8 ).

Dorsal cirri digitiform throughout, basally attached to dorsal ligule on anterior to mid-body chaetigers, about as long as dorsal ligule ( Fig. 9A–D View FIGURE 9 ), subdistally attached to dorsal ligule on mid-body to anterior half of posterior chaetigers, about 0.6–0.9 times longer than dorsal ligule ( Fig. 9E–F View FIGURE 9 ), distally attached to dorsal ligule on last 13 chaetigers, about 0.4 times as long as dorsal ligule ( Fig. 9F View FIGURE 9 ).

Dorsal ligule subconical on anterior chaetigers, subconical with blunt tips on anterior half of mid-body chaetigers, becoming small pennant-like lobe on posterior half of mid-body to posterior chaetigers ( Fig. 9A–F View FIGURE 9 ); base of dorsal ligule slightly elongate and broader on mid-body chaetigers, markedly elongate and broader on posterior chaetigers ( Fig. 9D–F View FIGURE 9 ). Notopodial prechaetal lobe absent.

Median ligule subconical throughout, shorter than dorsal ligule and neuroacicular ligule on anterior chaetigers, longer than neuroacicular ligule on mid-body to posterior chaetigers ( Fig. 9A–F View FIGURE 9 ).

Neuroacicular ligule with predominant inferior lobe on anterior to mid-body chaetigers, inferior and superior lobes subequal in length on posterior half of mid-body to posterior chaetigers, about 1.3 times as long as ventral ligule on anterior to mid-body chaetigers, about as long as ventral ligule on posterior chaetigers. Neuropodial postchaetal lobe present throughout. Ventral ligule subconical throughout. Ventral cirri mid-ventrally attached to ventral edge of parapodia, about 0.7 times as long as ventral ligule on anterior to mid-body chaetigers, about 0.5 times as long as ventral ligule on posterior chaetigers ( Fig. 9A–F View FIGURE 9 ).

Notochaetae present from chaetiger 3 to posterior chaetigers, homogomph spinigers present throughout ( Fig. 10A View FIGURE 10 ). Supra-acicular fascicle of neuropodia: homogomph spinigers and short-bladed heterogomph falcigers with serrations present ( Fig. 10B–C View FIGURE 10 ). Subacicular fascicle of neuropodia: a single heterogomph spiniger present from chaetiger 45 to posterior chaetigers and short-bladed heterogomph falcigers with serrations present throughout ( Fig. 10D–E View FIGURE 10 ).

Pygidium crenulated; anal cirri cirriform, as long as last 5 chaetigers.

Variation. Longest tentacular cirrus reached chaetiger 3–10 (n= 20). Apodous anterior segment ranged about 1.3-1.6 (n= 10) times longer than chaetiger 1. Number of lateral teeth on cutting edge of the jaws ranged 5–10 (n= 22). Paragnath numbers in Area II ranged 29–49 (left) and 18–46 (right) in 4–5 rows (n= 22), Area III 54–91 in 3–5 rows (n= 22), Area IV 36–93 (left) and 44–112 (right) in 5 rows (n= 22), Area V 1–2 (n= 22), Area VII–VIII 22–30 (n= 22), respectively. Heterogomph spinigers in the subacicular fascicle of the neuropodia commenced on chaetiger 37–41 (n=2). Length of anal cirri cirriform ranged from as long as last 5–10 chaetigers (n= 6).

Epitoke: Based on specimen NMNS 8383-34 (1), ovigerous female, complete, body depressed, body length 32.0 mm with 99 chaetigers; beige in alcohol ( Fig. 11A View FIGURE 11 ). Body divided into two regions: 1) pre-natatory region from chaetiger 1 to 13; 2) natatory region from chaetiger 14 to end of body.

Prostomium and apodous segment similar to atoke except enlarged eyes ( Fig. 11A View FIGURE 11 ). Jaws similar to atoke. Pharynx with dark brown jaws, each with 3–4 lateral teeth; paragnath pattern: I=1; II=42 (left), 41 (right), in 5 comb-like rows; III=65, in 4 transverse comb-like rows; IV=77 (left), 77 (right), in 5 comb-like rows with additional cones and p-bars in sigmoid towards the jaws; V=3, in triangle; VI=1 (left), 1 (right), shield-shaped bars; VII–VIII=26, p-bars and cones interspaced, p-bar row slightly behind cone row, one paragnath on each furrow and ridge regions ( Fig. 11B–C View FIGURE 11 ). Ridge pattern of areas VI–V–VI, υ-shaped ( Fig. 11B View FIGURE 11 ).

Pre-natatory region: Dorsal cirri robust with swollen base from chaetiger 1 to 7, basally attached to dorsal ligule, about 1.2 times longer than dorsal ligule ( Fig. 12A View FIGURE 12 ), digitiform on chaetiger 8 to 13, basally attached to dorsal ligule, about as long as dorsal ligule ( Fig. 12B View FIGURE 12 ). Dorsal ligule subconical, about as long as median ligule ( Fig. 12A, B View FIGURE 12 ). Medial ligule subconical. Neuroacicular ligule with predominant inferior lobe. Neuropodial postchaetal lobe present. Ventral ligule subconical. Ventral cirri robust on chaetiger 1–7, becoming digitiform from chaetiger 8 to 13 ( Fig. 12A–B View FIGURE 12 ).

Natatory region: Dorsal cirri digitiform to posterior end, basally attached to dorsal ligule on anterior to anterior half of posterior chaetigers, about as long as dorsal ligule, distally attached to dorsal ligule, about 0.4 times as long as dorsal ligule ( Fig. 12C–F View FIGURE 12 ). Dorsal cirrus lobe present from chaetiger 14 ( Fig. 12C View FIGURE 12 ), becoming kidney-shaped lamellae from chaetiger 17 to mid-body chaetigers ( Fig. 12D–E View FIGURE 12 ), reduced progressively in size thereafter, absent on posterior half of posterior chaetigers ( Fig. 12F View FIGURE 12 ).

Dorsal ligule subconical with blunt tips on anterior to anterior half of posterior chaetigers ( Fig. 12C–F View FIGURE 12 ), markedly elongate on posterior half of posterior chaetigers ( Fig. 12F View FIGURE 12 ).

Median ligule subconical on anterior chaetigers to posterior end, longer than neuroacicular ligule throughout ( Fig. 12C–F View FIGURE 12 ).

Neuroacicular ligule with predominant inferior lobe. Neuropodial postchaetal lobe present throughout, rounded on anterior chaetigers, lamellae present from mid-body to posterior chaetigers ( Fig. 12C–F View FIGURE 12 ). Ventral ligule subconi- cal throughout. Ventral cirri digitiform throughout, basally attached to ventral edge of parapodia, about as long as ventral ligule; ventral cirrus lobe and lamellae present throughout, reduced progressively in size toward posterior end ( Fig. 12C–F View FIGURE 12 ).

Notochaetal homogomph spinigers present from chaetiger 3 to 16 and from chaetiger 85 to posterior end ( Fig. 13A View FIGURE 13 ), homogomph spinigers replacing by natatory chaetae from chaetiger 17 to 84. Supra-acicular fascicle of neuropodia: homogomph spinigers and short-bladed heterogomph falcigers with serrations present from chaetiger 3 to 16 and from chaetiger 80 to posterior end ( Fig. 13B–C View FIGURE 13 ), homogomph spinigers replacing by natatory chaetae from chaetiger 17 to 79 ( Fig. 13D–E View FIGURE 13 ). Subacicular fascicle of neuropodia: homogomph spinigers and natatory chaetae present from chaetiger 17 to 84 ( Fig. 13D, E View FIGURE 13 ), heterogomph spinigers present from chaetiger 80 to posterior end ( Fig. 13D View FIGURE 13 ), short-bladed heterogomph falcigers with serrations present from chaetiger 3 to 16 and from chaetiger 80 to posterior end ( Fig. 13D–F View FIGURE 13 ).

Variation. Male epitoke (specimen NMNS 8383-34 (2)) has digitiform dorsal cirri commenced on chaetiger 7. Dorsal cirrus lobe has not expanded to lamellae on any chaetiger. Neuropodial postchaetal lobe has not broadly expanded and always shorter than median ligule. Parapodial chaetae have not been replaced by natatory chaetae in the natatory body region ( Fig. 14A–F View FIGURE 14 ).

Distribution. Geser, Indonesia, Western Australia, eastern and southern Taiwan.

Remarks. The present species is similar to P. trimaculata in term of paragnath patterns of the pharynx, morphology of parapodia, presence of glands on all three ligules of in most of chaetigers, and chaetal patterns ( Bakken 2007: 167–168, fig. 13A–E; Figs 8B–C View FIGURE 8 , 9A–F View FIGURE 9 , 10A–E View FIGURE 10 , Table 1). However, minor variations are noted between the present specimens and P. trimaculata : 1) the present specimens have a range of 1 to 3 conical paragnaths in Area V of the pharynx (versus 3); and 2) no blacks spots on parapodia in fresh specimens of the present study (versus pres- ence of black spots). Bakken (2007) stated that those spots are glands commonly seen in parapodia of nereidids, but now vaguely visible in the lectotype.

Epitokes of P. trimaculata are described for the first time in the present study. Different sexes show significant differences in morphological modifications. The female epitoke has a greater number of chaetigers and greater degree of morphological modifications on these chaetigers than that of the male epitoke. These morphological differences include that the female epitoke has: 1) about 90% (versus about 50%) of chaetigers with at least some degree of morphological modifications; 2) a dorsal small lobe on notopodial ligules and neuropodial ligule on modi- fied chaetigers (versus absent); 3) well-developed of dorsal cirrus lamellae, neuropodial postchaetal lamellae, and neuropodial ventral cirrus lobe and lamellae on the corresponding body segments (versus all moderate developed); 4) natatory chaetae on natatory body region (versus absent); and 5) different arrangement of notochaetae and neu- rochaetae on natatory body region than that of atokous individuals (versus similar arrangement) ( Figs 11–14 View FIGURE 11 View FIGURE 12 View FIGURE 13 View FIGURE 14 ).