Pseudopolydora auha, 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 : 140-143

Pseudopolydora auha sp. nov.

urn:lsid:zoobank.org:act:EEC92C7B-00F9-4480-AF4C-09B5877F563C

Figs 1D , 11

Diagnosis

Caruncle to end of chaetiger 6. Branchiae present beyond the middle of the body. Pygidium bilobed.

Etymology

The name refers to the type locality of the species in the intertidal of Auha Island, Arabian Gulf.

Material examined

Holotype KUWAIT • 1 spec.; Arabian Gulf, Auha Is. ; 29.3764° N, 48.4391° E; 29 Jan. 2017; Vasily I. Radashevsky leg.; low intertidal; from shell limestone encrusted by coralline alga; MIMB 40907 .

Paratype KUWAIT • 1 spec.; same collection data as for holotype; GenBank 16S gene MW904103 , GenBank 18S gene MW904112 , GenBank 28S gene MW904156 , GenBank Histone 3 gene MW923741 ; used entirely for molecular analysis .

Description

Two complete individuals in good condition with palps were found together in a shell limestone encrusted by coralline alga. The 22-chaetiger individual is designated as the holotype. The 42-chaetiger paratype was examined and then used entirely for molecular analysis.

Holotype about 2 mm long, 0.37 mm wide with 22 chaetigers ( Fig. 11A ). Paratype about 5 mm long, with 42 chaetigers. Pigmentation absent on body and palps. Prostomium anteriorly bifid, with two short triangular lobes ( Fig. 11A ), posteriorly extending to end of chaetiger 6 as a low caruncle in both types. Occipital antenna present on caruncle between palps. Two pairs of black eyes arranged trapezoidally, comprising one pair of median eyes, and one pair of lateral eyes situated anteriorly and set wider apart. Palps as long as 15–20 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, and small lamellae in both rami; 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; posteriorrow capillaries on these chaetigers arranged in vertical series. Posterior notopodia with a few long alimbate capillary chaetae.

Chaetiger 5 slightly larger than chaetigers 4 or 6, with dorsal superior capillaries, two kinds of notopodial spines arranged in a double U-shaped row, and ventral capillaries; noto- and neuropodial postchaetal lamellae same as on chaetiger 4 ( Fig. 11D ). Dorsal superior capillaries slightly shorter and fewer than those capillaries on chaetiger 4. Ventral capillaries same in size, number and arrangement (in three groups) as those on chaetiger 4. 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 4–6 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 tooth and concavity forming a long flag-like pointed transparent tip which is usually broken in worn old spines in the anterior upper part of row ( Fig. 11E ). Inner (posterior-row) notopodial spines 4–5 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. 11E ).

Hooks in neuropodia from chaetiger 8, up to 20 in a series, not accompanied by capillaries, in posterior chaetigers situated on top of prominent fleshy neuropodial lobes. 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. 11F ).

Branchiae from chaetiger 7 to chaetiger 15 in holotype, and to chaetiger 24 in paratype, on chaetiger 7 slightly shorter than those on chaetiger 8, full-sized from chaetigers 9–10, free from notopodial postchaetal lamellae, flattened, with surfaces oriented perpendicular to body axis, with longitudinal ciliation (extension of nototroch) running on inner edge.

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

Glandular pouches in neuropodia from chaetiger 1, largest and paired in each neuropodium in chaetigers 6 and 7, single in other neuropodia.

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

Nephridia from chaetiger 4 onwards.

MG staining

Intensely stained anterior part of the prostomium in front of eyes, and dorso-lateral sides of the peristomium. Weakly stained lateral sides of chaetigers and scattered glandular cells on the ventral side of chaetigers.

Habitat

The two types of P. auha sp. nov. were found together in a shell limestone encrusted by a coralline alga. Whether the worms made the burrows themselves or occupied empty holes made by other organisms remains uncertain.

Reproduction

Both examined individuals of P. auha sp. nov. were juveniles.

Remarks

In the Arabian Gulf, adults of P. auha sp. nov. appear very similar to those of P. antennata and P. melanopalpa sp. nov. (see below). They all have heavy spines in the notopodia of chaetiger 5 of the same morphology, branchiae beyond the middle of the body, and the bilobed pygidia with dorsal and ventral clefts (characters shared by all members of the P. antennata -complex, see below in the Discussion). However, they can be distinguished by the prostomium shape, length of the caruncle, and palp pigmentation. In P. antennata , the prostomium is anteriorly bifurcated, with two long pointed antero-lateral processes (to which the name of the species was referred), whereas in P. auha sp. nov. and P. melanopalpa sp. nov. the prostomia are incised, with two short lobes. In P. antennata , the caruncle extends posteriorly maximum to the end of chaetiger 4, whereas in P. melanopalpa sp. nov. the caruncle extends to the end of chaetiger 5, and in P. auha sp. nov. it extends to the end of chaetiger 6.

Adults of P. auha sp. nov. appear very similar to those of P. uphondo Simon, Sato-Okoshi & Abe, 2017 and P. eriyali Simon, Sato-Okoshi & Abe, 2017 both of which were described from South Africa by Simon et al. (2019). They share the characters of the P. antennata -complex (see below in the Discussion); the morphological differences between the three species are very subtle (see Simon et al. 2019: table 1) although genetically they are well separated ( Fig. 2 ). Adult P. eriyali and P. auha sp. nov. have caruncles extending to the end of chaetiger 6, while in P. uphondo the caruncle extends to the end of chaetiger 5. Additional specimens of P. auha sp. nov. should be examined to understand the morphological variability of this species and the differences between this species and P. eriyali and P. uphondo .

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. 11. Adult morphology of Pseudopolydora auha sp. nov., holotype (MIMB 40907), formalin-fixed and stained with MG). A. Anterior end, dorsal view. B. Posterior chaetigers, ventral view. C. Posterior end, left lateral view. D. Notopodium of chaetiger 5. E. Notochaetae of chaetiger 5. F. A series of hooded hooks from neuropodium of chaetiger 12. Abbreviations: arrow showing the direction towards the inside of the U-shaped row of spines of chaetiger 5; an = anterior-row spine from notopodium of chaetiger 5;no = notopodial postchaetal lamella; po = posterior-row spine from notopodium of chaetiger 5; su = dorsal superior capillary chaetae. Scale bars: A = 100 µm; B–D = 50 µm; E–F = 20 µm.

Fig. 2. Majority rule consensus tree of the Bayesian inference analysis of the combined 16S (234 bp), 18S (1639 bp), 28S (294 bp), and Histone 3 (306 bp) sequences (2473 bp in total) of Pseudopolydora spp. rooted with sequences of Polydorella dawydoffi Radashevsky, 1996. Posterior probabilities are shown on the branches. The numbers without letters preceding collecting locations are unique numbers from the VIR database linking the individuals on the tree with the sampling data in Table 1 and Supp.Table ESM1. Pseudopolydora complexes are defined by unique sets of characters shared by the species.