Dendronereis chipolini, Hsueh, 2019

Hsueh, Pan-Wen, 2019, Two new species of nereidids (Annelida, Polychaeta) from Taiwan, Zootaxa 4652 (3), pp. 544-556 : 545-550

Dendronereis chipolini n. sp.

Figs 1 A–C, 2A–E, 3A–L, 4A–H, Table 1

Material examined. Holotype ( NMNS 7861-001 ), brackish aquaculture ponds nearby the mouth of Kaoping River (22°28.72´N 120°25.93´E), sandy mud bottom, 28 October 1994 ; 19 paratypes. Eighteen ones ( NMNS 7861-002 – 019 ), collection, location, habitat and date information are the same as holotype ; one paratype ( NMNS 7861-020 ), Chigu (23°3.42´N 120°3.62´E), sandy mud bottom, 6 May 2009.

Diagnosis. Dendronereis with pharynx with solitary papillae on oral ring only; seven to eight pairs of branchiae, 8 th pair of branchiae if present, minute, with branchial filaments arising from edges of slightly enlarged notopodial dorsal cirrophores; neuropodia of anterior chaetigers with short blunt-tipped blades homogomph spinigers in upper and lower fascicle.

Description. Holotype ( NMNS 7861-001), complete, 105 mm long (48 and 62, from two other complete specimens; paratypes ( NMNS 7861-004, 008)), with 145 (115 and 147) chaetigers, maximum width 3.0 mm at chaetiger 10, excluding parapodia; light brown in alcohol ( Fig. 1A ). Prostomium bent dorsally, wider than long, frontal margin with shallow cleft, with narrow longitudinal grove extending to middle of prostomium; one pair of antennae arising anteriorly; palps with palpophores conical, slightly longer than wide, tapered palpostyles digitate, blunt, barely exposed. Two pairs of blackish, reniform or semilunar, similar sized eyes, with lenses, trapezoid arranged. Peristomium distorted by pharynx eversion, twice wider than long, four pairs of tentacular cirri with distinct cir- rophores, longest posterior tentacular cirri extended to chaetiger 9 (6–9, in paratypes NMNS 7861-002–4, 006, 008) ( Fig. 1B ). Pharynx with one pair of translucent, light brown jaws, each with 9–10 lateral teeth right and left, respectively (9–10 in paratypes ( NMNS 7861-002–4, 009, 014, 017, 019)); paragnaths absent; papillae large, uniseriate, digitate to hemispherical, present only on oral ring ( Fig. 1B, C ), numbers of papillae at each area as: Area V = 0 (0, from paratypes ( NMNS 7861-002–4, 009, 014, 017, 019)); Area VI = 1, 1 (1, 1, from paratypes ( NMNS 7861- 002–4, 009, 014, 017, 019)); Area VII/VIII = 5 (2–6, from paratypes ( NMNS 7861-002–4, 009, 014, 017, 019)) in one transverse row.

Chaetigers 1 and 2 with neuroaciculae only; noto-aciculae present from chaetiger 3 ( Fig. 3 A–D). Dorsal cirri attached basally to notopodial dorsal ligules, with cirrophores; dorsal cirri longer than dorsal ligules on anterior chaetigers ( Fig. 3 A–H), thereafter gradually reducing size, markedly shorter than dorsal ligules in first to third branchial segments, becoming small and forming tips of branchiae in fourth to seventh branchial segments ( Figs 2 B–D, 3I, J), remaining small to posterior end segments; notopodial dorsal cirrophores round, short on chaetigers 1 and 2 ( Fig. 3 A–D), gradually enlarged and depressed along chaetigers 3 to 21 (20 for individuals with seven pairs of branchiae) ( Fig. 2 B–D), thereafter abruptly reduced in size, small to posterior end segments. Both notopodial dorsal and medium ligules progressively longer from chaetiger 1 to 17 ( Figs 2B, C , 3 A–D), markedly reduced in length from chaetigers 18–20, thereafter remaining short ( Figs 2E , 3 K–L). Notopodial prechaetal lobe present from chaetigers 3 to 13, round ( Fig. 3E, G ). Neuropodia of chaetiger 1 with one prechaetal lobe and three (2 for paratype ( NMNS 7861-002)) uneven sized postchaetal lobes ( Fig. 3A, B ), chaetiger 2 with one prechaetal lobe and four (3 for para- type ( NMNS 7861-002)) uneven sized postchaetal lobes ( Fig. 3C, D ), chaetiger 3 to 9 with two prechaetal lobes and five to six subequal postchaetal lobes (four for paratype ( NMNS 7861-002), mostly five for other paratypes) ( Fig. 3E, F ), chaetiger 10 to 14 with two prechaetal lobes and seven subequal postchaetal lobes, chaetiger 15 to 17 with one prechaetal lobe and no postchaetal lobe ( Figs 2B, C , 3I, J ), chaetiger 18 to posterior end without prechaetal lobe and with one postchaetal lobe ( Figs 2D, E , 3 K–L). Ventral cirri attached to base of neuropodia, small throughout.

Notochaetae present from chaetiger 3 to posterior end, all homogomph spinigers with serrated blades; most notochaetae embedded in body flesh with tips of few notochaetae exposed in anterior chaetigers, all notochaetae exposed in subsequent chaetigers ( Fig. 4A, B ). Neurochaetae present from chaetiger 1 to posterior end; chaetigers 1 and 2 with homogomph spinigers, serrated blade medium-sized ( Fig. 4C ), chaetigers 3 to 12 with serrated short to long homogomph spinigers in upper and lower neuropodial fascicles ( Fig. 4D, E ), short blade homogomph spinigers blunt-tipped ( Fig. 4E ); thereafter chaetigers with only long homogomph spinigers with serrated blade.

Branchiae bipinnate, depressed, conical present along chaetigers 15 to 22 (15 to 21 if only seven pairs of branchiae present) ( Figs 1A , 2A ); first to third branchial pairs with conical to clavate lateral lobes arising from enlarged, depressed notopodial dorsal cirrophores, lateral lobes progressively smaller distally ( Fig. 2B, C ); numbers of lobes on each branchia as: first pair=0/7 (left inner/outer edges, respectively) (0/6, from paratype MNMS 7861-002) and 0/6 (right inner/outer edges, respectively) (0/5, from paratype MNMS 7861-002); second pair=0/10 and 5/9 (0/10 and 0/10); third pair=7/8 and 7/ 9 (8/10 and 9/12) ( Fig. 2C ); fourth to seventh pairs with lateral lobes larger, fully developed, arising from notopodial base, with main stem and bipinnate branchial filaments, each filament with many double-rows of smaller filaments; numbers of branchial filaments on each branchia as: fourth pair=15/17 (13/14) (left pinnate) and 14/15 (13/16) (right pinnate); fifth pair=14/15 and 14/17 (20/22 and 15/17); sixth pair=15/16 and 15/18 (15/16 and 16/17); seventh pair=14/17 and 14/15 (11/11 and 11/12) ( Fig. 2D ), eighth pair=2/2 and 1/2 (2/ 3 and 2/4) ( Fig. 2E ) (Variations on numbers of branchial pairs and branchial clavate lobes and filaments see Table 1 ).

Pygidium round, anus with multiple incisions ( Fig. 4F ); one pair of anal cirri, attached ventrally, elongate, tapered, reaches 11 th chaetiger from posterior end.

Etymology. The species is dedicated to the memory of Mr. Chi Po-Lin (27 December 1964 – 10 June 2017) aerial photographer and documentary film director who made an immense contribution to environmental protection in Taiwan.

Type locality. Brackish aquaculture ponds nearby the mouth of Kaoping River, Kaohsiung, Taiwan .

Distribution. Only known from the type locality and brackish aquaculture ponds adjacent to the Chigu lagoon, Tainan, Taiwan.

Remarks. Dendronereis chipolini n. sp. resembles D. aestuarina by having a similar number of branchial pairs (8 vs. 7 – 8). However, D. chipolini n. sp. can be distinguished from D. aestuarina by: 1) morphology of the third branchial pair, 2) morphology of the eighth branchial pair if they are present, 3) morphology of neuropodia, and 4) morphology of neuropodial homogomph spinigers. The third pair of branchiae in D. chipolini n. sp. has clavate lobes on both edges of the branchiae, whereas that of D. aestuarina has only one edge with clavate lobes ( Southern 1921: 598, pl. XX, 4F; Fig. 2C , Table 1 ). About 50% of the collected specimens of D. chipolini n. sp. have eight pairs of branchiae. When the eighth pair of branchiae is present in D. chipolini n. sp., it is always poorly developed, with a few filaments arising on both edges of the small branchial stem ( Fig. 2E ). In contrast, the eighth branchial pair in D. aestuarina is always fully developed, with many filaments on both edges of the large branchial stem ( Southern 1921: 598, 601). The neuropodia in D. chipolini n. sp. have fewer anterior and posterior lobes in anterior chaetigers than that of D. aestuarina ( Southern 1921: 599 – 601, text-fig. 9; Fig. 3 A–F). Finally, chaetigers 3 to 12 of D. chipolini n. sp. have homogomph spinigers with blunt-tipped short blades with serrations in upper and lower fascicles of neuropodia, whereas D. aestuarina has none of this type of chaetae in neuropodia ( Southern 1921: 600–601, Plate XX, 4L–N; Fig. 4E ).

Figures

FIGURE 1. Dendronereis chipolini n. sp.; A, paratype (NMNS 7861-003), B–C, holotype (NMNS 7861-001): A, whole animal; B, anterior end, dorsal view; C, anterior end, ventral view, arrows indicate papillae on oral ring.Abbreviations: Pa, Papillae. Scale bars: A, 5.0 mm; B–C, 1.0 mm.

FIGURE 2. Dendronereis chipolini n. sp.; paratype (NMNS 7861-002): A, anterior region, branchial segments, dorsal view (numbers indicate branchial pairs); B, chaetiger 15, left parapodium, anterior view; C, chaetiger 17, left parapodium, anterior view; D, chaetiger 21, left parapodium, anterior view; E, chaetiger 22, left parapodium, anterior view. (Abbreviations: BF, branchial filaments; DC, dorsal cirri; NoDL, notopodial dorsal ligule; NoML, notopodial medium ligule; VC, ventral cirri, NeVL, neuropodial ventral ligule). Scale bars: A–D, 1.0 mm; E, 0.2 mm.

FIGURE 3. Dendronereis chipolini n. sp.; paratype (NMNS 7861-002):A, chaetiger 1, left parapodium anterior view; B, same, posterior view; C, chaetiger 2, left parapodium, anterior view; D, same, posterior view; E, chaetiger 3, left parapodium, anterior view; F, same, posterior view; G, chaetiger 9, left parapodium, anterior view (neuropodial ventral cirri not showed); H, same, posterior view (neuropodial ventral cirri not showed); I, chaetiger 15, left parapodium, posterior view; J, same, posterior view; K, chaetiger 23, left parapodium, anterior view; L, same, posterior view. (Abbreviations: BF, branchial filaments; DC, dorsal cir- rus; NoDL, notopodial dorsal ligule; NoML, notopodial medium ligule; NeL, neuropodial lobes; NoPL, notopodial prechaetal lobe; VC, ventral cirrus, NeVL, neuropodial ventral ligule). Scale bars: A–L, 0.5 mm.

FIGURE 4. Dendronereis chipolini n. sp.; A–E, paratype (NMNS 7861-002); F, paratype (NMNS 7861-004): A, chaetiger 9, left parapodium, anterior view (most notochaetae embedded in body flesh with tips of few chaetae exposed); B, chaetiger 15, left notopodial and notochaetae, anterior view; C, chaetiger 1, left neuropodial homogomph spinigers; D, chaetiger 3, left parapodium, neuropodial homogomph spinigers of upper fascicle, left; E, chaetiger 10, left parapodium, short and blunt-tipped neuropodial homogomph spinigers; F, pygidium, dorsal view, arrows indicate bases of anal cirri. (Abbreviations: AC, Anal cirrus; DC, notopodial dorsal cirri; NoDL, notopodial dorsal ligule; NoML, notopodial medium ligule; NoPL, notopodial prechaetal lobe). Scale bars: A–B, 0.1 mm; C–E, 0.05 mm; F, 0.5 mm.

Tables

TABLE 1. Variation in numbers of branchial pairs and clavate lobes or filaments on each branchial branch of Dendronereis chipolini n. sp. BL=body length (mm), BL=maximum body width (mm), LI=left inner edge, LO=left outer edge, RI=right inner edge, RO=right outer edge. “-“ = no data.

NMNS #	BL	BW	# pair	1st	2nd	3rd	4th	5th	6th	7th	8th
				LO/ RO	LO/LI/RI/ RO	LO/LI/RI/RO	LO/LI/RI/RO	LO/LI/RI/RO	LO/LI/RI/ RO	LO/LI/RI/RO	LO/LI/RI/ RO
7861-001	105	1.3	8	7/6	10/0/5/9	8/7/7/9	17/15/14/15	15/14/14/17	16/15/15/18	17/14/14/15	2/2/1/2
7861-002	29+	1.4	8	6/5	10/0/0/10	12/9/8/10	16/13/14/14	18/17/15/17	16/15/16/17	11/11/11/12	3/2/2/4
7861-003	93+	1.6	8	5/5	9/0/0/9	9/8/8/9	16/15/15/16	16/15/16/17	16/15/17/18	17/16/17/18	7/5
7861-004	48	1.1	7	6/6	9/0/0/11	10/9/10/10	12/12/13/14	12/11/12/13	11/10/12/13	11/10/11/12
7861-005	39+	0.6	8	5/5	7/0/0/7	8/10/-/-	11/10/-/-	12/11/-/-	14/13/-/-	10/10/-/-
7861-006	51+	0.8	7	6/5	7/4/-/-	8/5/6/9	13/12/13/14	13/12/12/13	12/11/13/14	11/10/11/12
7861-007	75+	0.9	7	5/6	10/0/0/8	9/6/5/9	14/13/12/13	13/12/-/-	15/14/13/14	15/14/12/13
7861-008	62	1.1	7	6/6	9/0/0/9	9/7/7/9	14/13/14/15	16/15/16/15	16/15/17/18	15/13/14/15
7861-009	100+	1.4	8	5/7	9/0/0/7	11/8/8/13	15/14/16/17	16/15/17/17	19/18/16/17	18/17/17/18	2/3/8
7861-010	51+	1.4	8	6/6	11/0/0/9	11/6/6/10	14/13/11/12	15/14/14/15	16/15/15/16	15/14/15/17	3/2/5
7861-011	62+	1.1	7	7/7	9/0/0/9	9/6/7/9	14/12/13/14	13/12/14/15	13/12/15/16	13/12/14/15
7861-012	15+	1.3	8	5/5	9/0/0/9	10/6/6/10	15/14/14/15	16/15/15/16	17/16/15/16	15/13/16/14	1/3/2
7861-013	52+	1.3	7	7/6	10/0/0/10	9/8/5/10	15/14/14/15	16/16/17/17	16/15/16/17	14/13/15/16
7861-014	44+	1.4	8	6/6	8/0/0/8	9/6/6/11	14/13/13/14	15/14/13/15	16/15/15/16	16/15/16/15	1/3/2
7861-015	27+	0.8	7	6/6	8/0/0/8	8/7/6/10	16/14/12/13	14/14/12/13	13/12/11/12	12/12/11/12
7861-016	50+	1.1	8	4/6	9/0/0/9	8/7/7/10	14/13/14/14	11/12/14/15	14/13/14/15	-/-/11/12
7861-017	36+	1.3	7	6/6	8/0/0/8	10/7/8/10	15/14/16/17	16/15/16/17	16/17/17/15	17/16/16/17
7861-018	61+	1.3	8	5/5	9/0/0/8	8/6/6/8	17/16/13/14	18/17/15/16	16/15/14/15	18/17//14/15	3/4/3
7861-019	81+	1.6	7	6/6	8/0/0/9	8/6/7/9	15/14/14/-	16/14/15/16	15/14/14/15	13/12/14/15
7861-020	27+	0.8	7	7//7	8/5/0/7	8/6/7/9	13/12/10/12	14/13/11/13	11/10/12/13	12/11/10/12