Pseudopolydora melanopalpa, Radashevsky & Malyar & Pankova, 2021

Radashevsky, Vasily I., Al-Kandari, Manal, Malyar, Vasily V. & Pankova, Victoria V., 2021, Pseudopolydora (Annelida: Spionidae) from the Arabian Gulf, Kuwait, European Journal of Taxonomy 773 (1), pp. 120-168 : 152-156

Pseudopolydora melanopalpa sp. nov.

urn:lsid:zoobank.org:act:DA98F3F8-54B1-4CCC-BC82-16C3ABF0DC34

Figs 1D , 17–19

Diagnosis

Prostomium anteriorly incised, with two short rounded lobes. Caruncle to end of chaetiger 5. Fine black pigment scattered on distal part of palps.

Etymology

The species name refers to fine black pigment scattered on the distal part of palps in adults.

Material examined

Holotype KUWAIT • 1 spec.; Arabian Gulf, Sulaibikhat Bay, desalinization station outfall area ; 29.36157° N, 47.81915° E; 6 Feb. 2019; Vladimir A. Grintsov leg.; low intertidal; mud; MIMB 40908 .

Paratypes KUWAIT • 5 specs; same collection data as for holotype; MIMB 40909 .

Description

All types: anterior fragments of females in good condition with palps; one 25-chaetiger fragment with a few small newly regenerated posterior achaetous segments with a small bilobed pygidium. Holotype: 39-chaetiger anterior fragment about 10 mm long, broken in the middle ( Fig. 17A ). Specimens up to 10 mm long, 1 mm wide with 45 chaetigers; when complete, worms apparently up to 15 mm long with at least 60 chaetigers. No pigmentation on body; fine black pigment scattered on distal part of palps ( Figs 17A, C, E , 18C ). Prostomium anteriorly incised, with two short rounded lobes ( Figs 17C–E , 18A–B ), posteriorly extending to end of chaetiger 5 (end of chaetiger 4 in holotype) as a low caruncle. Peristomium with two lateral lips as thick folds in front of large ventral lip ( Fig. 17A ). Short occipital antenna present on caruncle between palps ( Fig. 18C ). Two pairs of black eyes arranged trapezoidally, comprising one pair of median eyes, and one pair of slightly larger lateral eyes situated anteriorly and set wider apart. Palps as long as 10–15 chaetigers, with frontal longitudinal groove lined with fine cilia, and short compound non-motile cilia arising directly from palp surface sparsely arranged in line on sides of groove and sparsely scattered on lateral and abfrontal palp surfaces.

Chaetiger 1 with short capillaries in neuropodia, small notopodial lamellae and well-developed neuropodial postchaetal lamellae; notochaetae absent. Chaetiger 2 notochaetae all slender capillaries with narrow limbation. Anterior-row notopodial capillaries on chaetiger 3 with slightly enlarged wing; capillaries on chaetiger 4 with wing slightly larger than on chaetigers 3. Anterior-row capillaries on chaetigers 3, 4, 6 and 7 arranged in J-shaped series; posterior-row capillaries on these chaetigers arranged in vertical series ( Figs 17A–B , 18C ). Posterior notopodia with a few long alimbate capillary chaetae.

Chaetiger 5 same in size as chaetigers 4 or 6, with dorsal superior capillaries, two kinds of notopodial spines arranged in a double U-shaped row, and ventral capillaries; notopodial postchaetal lamellae absent; neuropodial lamellae same as on chaetigers 4 and 6 ( Figs 17A–B , 18C ). Dorsal superior capillaries shorter and fewer than those capillaries on chaetigers 4 and 6. Ventral capillaries same in size, number and arrangement (in three groups) as those on chaetigers 4 and 6. Upper posterior part of double U-shaped row of spines slightly lower than upper anterior part. Newly developed spines in posterior upper part of U-shaped row slightly larger than older spines in anterior upper part of row. Outer (anterior-row) notopodial spines up to 12 in a series, with distal part of stem enlarged, with concavity on top and large triangular tooth on its side directed upwards and facing towards the inside of the U-shaped row of spines; fine bristles arising from concavity forming long flag-like pointed transparent tip which usually broken in worn old spines in anterior upper part of row ( Fig. 19A–B, D ). Inner (posterior-row) notopodial spines up to nine in a series, falcate, with short rounded distal part geniculate, with subdistal bulbous swelling bearing very short fine bristles and facing towards the inside of the U-shaped row of spines ( Fig. 19A, C–D ).

Hooks in neuropodia from chaetiger 8, up to 30 in a series, not accompanied by capillaries. Hooks bidentate, with upper tooth closely applied to main fang; upper part of shaft with constriction; lower part of shaft bent at right angle ( Fig. 19E–F ).

Branchiae from chaetiger 7 to chaetiger 42, up to 36 pairs, on chaetiger 7 1.5–2 times as short as those on chaetiger 8, full-sized from chaetigers 10–11, fewer in small individuals, free from notopodial postchaetal lamellae, flattened, with surfaces oriented perpendicular to body axis, with longitudinal ciliation (extension of nototroch) on inner edge.

Pygidium bilobed, with two semi-oval lateral lobes, white due to great number of spindle-shaped glandular cells with striated content.

Subspherical to irregular shape glandular cells with striated content present on dorsal side of chaetigers. Cells few on anterior and posterior chaetigers, forming distinct paired gatherings from chaetiger 12 to chaetigers 30–35 ( Figs 17D , 18A ).

Glandular pouches in neuropodia from chaetiger 1, largest and paired in each neuropodium in chaetigers 6 and 7, single in other neuropodia ( Fig. 19E ).

Digestive tract without ventral buccal bulb and gizzard-like structure, without pigmentation.

Nephridia from chaetiger 4 onwards. Distal parts of nephridia on female fertile chaetigers enlarged, containing glandular cells which absorbing MG and therefore well seen in fixed specimens from chaetiger 13 ( Fig. 18A, E–F ). Nephridia of chaetiger 13 used to release gametes from chaetiger 12. In female fertile chaetigers, paired nephridia on each chaetiger opening to exterior via common middorsal nephridiopore anteriorly to nototroch ( Fig. 18F ).

MG staining

Intensely stained anterior part of prostomium in front of eyes, dorso-lateral sides of peristomium, scattered glandular cells on dorsal side of chaetigers 7–11, and paired gatherings of glandular cells on dorsal side from chaetiger 12 to chaetigers 30–35. Weakly stained lateral sides of chaetigers; scattered glandular cells on ventral side of chaetigers ( Figs 17–18 ).

Habitat

Adult P. melanopalpa sp. nov. inhabit silty tubes in the muddy intertidal.

Reproduction

All six type specimens of P. melanopalpa sp. nov. are females with oocytes from chaetiger 12 to chaetigers 32–40. Paired ovaries are attached to the segmental blood vessels in fertile chaetigers ( Fig. 19G ). The developed coelomic oocytes are about 120 µm in diameter, with smooth thin envelope less than 1 µm thick.

Remarks

Adult P. melanopalpa sp. nov. share a series of characters with members of the P. antennata -complex (see below in the Discussion). They differ, however, from other species of this complex by having black pigment on the distal part of palps, and the prostomium with two rounded lobed instead of pointed fronto-lateral extensions (see Simon et al. 2019: table 1).

Distribution

Arabian Gulf: Kuwait ( Fig. 1D ).

Figures

Fig. 1. Maps showing records (yellow circles) and type localities (stars) of Pseudopolydora spp. from the Arabian Gulf, Kuwait (see Supp. Table ESM1). A. P. antennata (Claparède, 1868). B. P. arabica Radashevsky & Al-Kandari, 2020 (red star = type locality: Al-Salmiya, Kuwait). C. P. kuwaiti sp. nov. (red star = type locality: Al-Judailiat). D. Yellow star = type locality of Pseudopolydora auha sp. nov.: Auha Is.; red star = type locality of P. melanopalpa sp. nov.: Sulaibikhat Bay; green star = type locality of Pseudopolydora multispinosa sp. nov.: Al-Salmiya, Kuwait.

Fig. 17. Adult morphology of Pseudopolydora melanopalpa sp. nov. (formalin-fixed and stained with MG specimens). A. Holotype (MIMB 40908). B–E. Paratypes (MIMB 40909). A–E. Anterior ends, left lateral (A–B), dorsal (C–D), and ventral (E) view. Abbreviations: ch5 = chaetiger 5; la = lateral peristomial lip; pr = prostomium; ve = ventral peristomial lip. Scale bars = 200 µm.

Fig. 18. Adult morphology of Pseudopolydora melanopalpa sp. nov. (formalin-fixed and stained with MG specimens, MIMB 40909). A–C. Anterior ends, dorsal (A), ventral (B), and left lateral (C) view. D. Middle chaetigers, left lateral view. E. Chaetigers 7–14, dorsal view. F–G. Middle chaetigers, dorsal view. Abbreviations: ch5, ch13 = chaetigers 5 and 13; ne = nephridia in female fertile chaetigers; oc = occipital antenna; po = nephridiopore. Scale bars = 200 µm.

Fig. 19. Chaetal and gamete morphology of Pseudopolydora melanopalpa sp. nov. (formalin-fixed and stained with MG specimens, MIMB 40909). A. Parapodia of chaetiger 5. B. Anterior-row spines of chaetiger 5, view from the outside of the U-shaped spine row.C. Posterior-row falcate spine of chaetiger 5, lateral view. D. Notopodial spines of chaetiger 5, lateral view. E. Neuropodium of chaetiger 10, showing glandular pouch associated with a series of hooded hooks. F. Hooded hooks from middle neuropodium. G. Small previtellogenic oocyte on a genital blood vessel. Abbreviations: arrows showing the direction towards the inside of the U-shaped row of spines; bv = genital blood vessel; gp = glandular pouch; ne = neuropodial postchaetal lamella; oo = oocyte; su = dorsal superior capillary chaetae; ve = ventral capillary chaetae. Scale bars: A, E = 50 µm; B–D, F–G = 20 µm.