Paradiopatra, EHLERS, 1887

Budaeva, Nataliya & Fauchald, Kristian, 2011, Phylogeny of the Diopatra generic complex with a revision of Paradiopatra Ehlres, 1887 (Polychaeta: Onuphidae), Zoological Journal of the Linnean Society 163 (2), pp. 319-436 : 339-347

PARADIOPATRA EHLERS, 1887 ( FIGS 12 AND 13 )

Diopatra (Paradiopatra) Ehlers, 1887: 73 .

Sarsonuphis Fauchald, 1982: 64 .

Notonuphis Kucheruk, 1978: 93 ; Paxton, 1986a: 35–36.

Paradiopatra Paxton, 1986a: 36–38 .

Type species: Paradiopatra fragosa Ehlers, 1887 .

Gender: Feminine.

Diagnosis: Median antenna shorter or equal to lateral antennae; anterior 2–4 pairs of parapodia modified, but not enlarged, with pseudocompound falcigers with long-to-moderately long pointed hoods; limbate chaetae smooth, without serration; branchiae pectinate, present only through median chaetigers or absent; postchaetal lobes limited to about ten anterior chaetigers; two pairs of anal cirri; maxillae VI absent.

Description: Living specimens as well as specimens stored in ethanol cream-coloured to yellowish or brownish. Some species demonstrating presence of transverse dark-brown pigmented bands across the dorsal side of anterior chaetigers. Size of worms varying from 0.3 to 4.5 mm in width and up to 167 mm (about 250 chaetigers) in length.

Prostomium ( Fig. 12A, B ) anteriorly rounded, bearing one pair of relatively short palps, reaching chaetigers 1 or 2; one pair of lateral antennae, reaching chaetigers 2–13, and single median antenna. Median antenna shorter or rarely equal in length to lateral antennae, reaching chaetigers 1–10. Both antennae and palps with ceratophores consisting of between three and ten rings; in some species rings of ceratophores with small lateral projections. Frontal lips usually ovoid, rarely spherical, always located anteroventrally on frontal margin of prostomium. Upper lips elongated; lower lip massive, with or without median section. One or two pairs of simple eyes present near the bases of palps or lateral antennae; often eyes absent. Nuchal grooves slightly curved with wide mid-dorsal separation, sometimes covered by anterior fold of peristomium. Peristomium as long as prostomium, bearing a pair of peristomial cirri; peristomial cirri present or absent.

Ventral pharynx containing maxillae and mandibles. Maxillae ( Fig. 12C ) usually dark brown, with five pairs of plates; maxillae III unpaired, maxillae VI absent. Mandibles ( Fig. 12D ) with relatively long and wide shafts; calcareous cutting plates with one or two indentations.

Anterior three (between two and four) pairs of parapodia modified, i.e. structurally different from more posterior parapodia ( Fig. 13 ). Modified anterior

C D Left MxIV Right MxIV Denticle Left MxV Right MxV Cutting plate

MxIII Left MxII Right MxII

Shaft Left MxI Right MxI parapodia with well-developed thick, triangular postchaetal lobes, and dorsal and ventral cirri. First pair of parapodia usually projecting lateroventrally or laterally, but always directing anteriorly. All following parapodia structurally similar in shape and directing strictly laterally; however, can be divided into transitional parapodia bearing exclusively limbate chaetae and unmodified parapodia with paired subacicular hooks in ventral fascicle. Few pairs of anteriormost unmodified parapodia still with visible postchaetal lobes; however, these lobes become smaller gradually and usually disappear on chaetiger 9 (chaetigers 5–15). Dorsal cirri well developed on all parapodia, becoming increasingly digitiform and slender posteriorly. Ventral cirri replaced by flat glandular pads, rounded or elongate in shape, from the first unmodified pair of parapodia.

Branchiae single strap-like, bifid, pectinate, or absent ( Fig. 13 ). In many species branchiae starting from chaetigers 6 or 7 as a single filament becoming pectinate on median chaetigers, and disappearing between chaetigers 20 and 83. In some species branchiae starting earlier (chaetigers 3 or 4) or later (chaetigers 9–24); however, they are never present on the posteriormost chaetigers terminating in the median part of the body. Pectinate branchiae usually consisting of between three and six relatively short (not longer that dorsal cirri) filaments, rarely reaching 11–14 filaments. Some species with very long and slender branchial filaments, of between three and six times the length of dorsal cirri.

Parapodia biramous, with reduced notopodia represented by thin notopodial aciculae located inside the parapodium and notopodial cirri. Neuropodia containing between one and six translucent to yellow neuroaciculae with sharply pointed tips and two fascicles of chaetae. Dorsal chaetal fascicle in modified parapodia containing between one and three simple capillary chaetae ( Figs 7B , 13A ), replaced by limbate chaetae in the following unmodified parapodia ( Figs 7J , 12D ). Ventral fascicle containing falcigers ( Fig. 13B ) or tapering chaetae ( Fig. 13C, D ), limbate chaetae ( Fig. 13E, F ), or subacicular hooks ( Fig. 13H ), replacing one another along the body. All falcigers with tiny spines scatterd along their shafts; however, in some species these spines may be organized into two longitudinal rows. Subacicular paired simple bidentate hooks with thin translucent paired hoods appearing posteriorly in the unmodified parapodia ( Figs 7N, O , 13H ).

Usually all modified parapodia have pseudocompound falcigers, i.e. the number of chaetigers with subulate ventral cirri matches the number of chaetigers with pseudocompound falcigers. However, in some fraction of specimens the last pair of modified parapodia having simple or pseudocompound sharply tapering chaetae in the ventral fascicle ( Figs 7F, G , 13C, D ). In the following unmodified parapodia both fascicles containing limbate chaetae: these are long and slender in the dorsal fascicle ( Fig. 13E ), and short and stout in the ventral fascicle ( Fig. 13F ). Paired subacicular hooks with translucent blunt hoods replacing ventral limbate chaetae from chaetigers 8–17, and continuing to the end of the body. Pectinate chaetae flat with slightly oblique distal margin bearing 11–29 small teeth ( Figs 7I , 13G ). Pectinate chaetae present in ventral fascicles of unmodified parapodia, usually starting around chaetiger 10.

Pygidium with two pairs of anal cirri, and with dorsal pair of cirri longer than ventral pair. Anus terminal. Majority of species building cylindrical tubes consisting of a relatively thick outer layer of mud particles and a thin inner parchment-like lining, but muddy tubes incrusted by dead foraminiferans as well as tubes made from fine sand are also known.

Remarks: Paradiopatra was defined by Paxton (1986a) based on the presence of peristomial cirri, long hoods on anterior falcigers, and absence or presence of pectinate branchiae. Sarsonuphis , a junior synonym of Paradiopatra , had previously been characterized by Fauchald (1982) with the same set of characters, plus cylindrical tube, short frontal lips, and relatively short ceratophores. All genera of the Diopatra complex have moderately long pointed hoods on anterior falcigers, at least in some species. Consequently, this character cannot be accepted as diagnostic for the genus Paradiopatra . Here, we suggest several additional diagnostic characters for Paradiopatra that may help to distinguish this genus from closely related genera, including the newly described ones.

Paradiopatra differs from Diopatra in lacking, rather than having, serrated limbate chaetae, this unique character of Diopatra (including Epidiopatra ) has been reported for all examined species, and is either mentioned or illustrated in the majority of Diopatra species descriptions ( Paxton & Bailey-Brock, 1986; Paxton, 1993, 1998, 2002; Paxton et al., 1995). Branchiae in Paradiopatra species (if present) terminate in the middle part of the body and never occur on the posteriormost chaetigers. In contrast, in Paxtonia gen. nov. and Protodiopatra gen. nov. well-developed branchiae are present in the posterior region of the body. In addition, Paradiopatra can be distinguished from Diopatra , Paxtonia gen. nov., and Protodiopatra gen. nov. by the presence of triangular-to-digitiform postchaetal lobes limited to anterior chaetigers 5–15, rather than continuing to the end of the body.

Paradiopatra minuta comb. nov. was described by McIntosh in 1885, and was referred to Notonuphis by Paxton (1986a) based on the absence of peristomial cirri and the presence of simple anterior bidentate falcigers with long pointed hoods. Here, we refer all Notonuphis species to Paradiopatra . The presence of simple falcigers is not previously reported for Paradiopatra species. As P. minuta comb. nov. is represented only by the anteriorly incomplete holotype, the presence of simple falcigers within Paradiopatra remains questionable.

Paradiopatra barrazai León-González, Rivera & Romero, 2004 was described from a subtidal soft- bottom biotope off El Salvador. It was characterized by the presence of tridentate pseudocompound falcigers with moderately long pointed hoods on the first four chaetigers. Paradiopatra barrazai also has digitiform postchaetal lobes on all chaetigers, and has large median tridentate hooks on chaetigers 5–28. These characters are typical for Kinbergonuphis and Mooreonuphis ( Fauchald, 1982) , and have not been reported for any other Paradiopatra species. Large median hooks were erroneously reported by Fauchald (1982) for P. lepta . Type and large non-type material of P. lepta has been re-examined by Paxton (1986a) and in the present study, and no such hooks were found. Consequently, P. barrazai may be referred to Kinbergonuphis or possibly represent a new genus; however, the type material was not studied and the taxonomic status of this species remains unresolved.

Paradiopatra kirkegaardi Budaeva, 2008 was originally described by Kirkegaard (1988) as Sarsonuphis fauchaldi Kirkegaard, 1988 from the west coast of Africa based on the presence of large lateral projections on palps and ceratophores, and single branchiae starting from chaetigers 9–16. Buzhinskaya (1985) described another species from the Sea of Okhotsk, Paradiopatra fauchaldi Buzhinskaya, 1985 , and, erroneously, referred it to Paradiopatra sensu Pettibone (1970) and Fauchald (1982). After the generic revision of onuphids performed by Paxton (1986a), all species previously referred to Sarsonuphis sensu Fauchald (1982) were transferred to Paradiopatra sensu Paxton (1986a) , and all species previously referred to Paradiopatra sensu Pettibone (1970) were transferred to a new genus, Anchinothria Paxton, 1986a . Consequently, two species with the same name, P. fauchaldi , occurred within the Paradiopatra . Budaeva (2008) re-examined the type material of S. fauchaldi and P. fauchaldi and suggested a new name for the former taxon: P. kirkegaardi . Paradiopatra kirkegaardi has strongly serrated limbate chaetae in all parapodia; this kind of chaeta is known only for Diopatra species , and has not been found in any other onuphids. Paradiopatra kirkegaardi closely resembles juveniles of D. dubia , a very common species in the same area ( Day, 1960; Detinova, 1993). We re-examined Detinova’s material and found various juveniles and adults of D. dubia . This species is characterized by the presence of lateral projections on all ceratophores, partly fused frontal lips, relatively long pointed hoods on anterior falcigers, and subacicular hooks starting from chaetiger 9. All these characters are also present in P. kirkegaardi . The difference between the two species occurs in the numbers of parapodia with pseudocompound falcigers and in the structure of the branchiae. Diopatra dubia has falcigers on the first four chaetigers and spiral branchiae starting from chaetigers 4–6, whereas P. kirkegaardi has only three chaetigers with falcigers and single branchiae. Diopatra juveniles may have a lower number of modified parapodia bearing pseudocompound falcigers than the adults ( Paxton, 1993; Fadlaoui et al., 1995; Budaeva & Fauchald, 2008). Here, we consider P. kirkegaardi as an unknown Diopatra species as no adult specimens were found in the same sample with supposed juveniles, and proper identification cannot be performed.

Paxton (1986a) suggested that two species of Kinbergonuphis , Kinbergonuphis abyssalis ( Fauchald, 1968) and Kinbergonuphis mixta ( Fauchald & Hancock, 1981) could be members of Paradiopatra based on the presence of pseudocompound falcigers with long pointed hoods. Both species were listed within the Kinbergonuphis , with a special note on the presence of characteristic falcigers and the absence of large median hooks. Kinbergonuphis abyssalis and K. mixta are known only from the type localities, and are represented by just a few specimens each. Acceptance of K. abyssalis as a valid species of Paradiopatra would induce a nomenclatural problem because we have accepted Notonuphis abyssalis sensu Imajima (1999) as a junior synonym of P. abyssalis . However, the type material was unavailable for examination; consequently, the validity of K. abyssalis and K. mixta has not been confirmed. Future investigations are needed for clarification of the status of both species.

Composition: Composed of 26 species.

Distribution: Worldwide; depth range 13–6350 m.

PARADIOPATRA FRAGOSA ( EHLERS, 1887)

( FIGS 14 AND 15; TABLE 3)

Diopatra (Paradiopatra) fragosa Ehlers, 1887: 75–76 , pl. 20, figs 7–14; pl. 21, figs 1–4.

Sarsonuphis fragosa Fauchald, 1982: 70–71 , fig. 25a–c.

Paradiopatra fragosa Paxton, 1986a: 38 .

Type material: MCZ 656 , Bibb Expedition Straits of Florida, South Marquesas , 24.223°N, 82.15°W, 609 m, 11 February 1869, coll. de Pourtales, L.F. (two syntypes) ; MCZ 766 , Florida, off Sand Key , 670 m, 17 February 1869 (syntype) ; MCZ 857 , Florida, off Bahia Honda , 756 m (syntype) .

Non-type material examined: MCZ 1017 (six) ; MCZ 2436 , Blake expedition, off Grenada, 12.059°N, 61.823°W, 1045 m, 2 March 1879 (five); Atlantic Slope and Rise Program : USNM 187999 , St . SA2-01 (one) ; USNM 188000 , St . SA2-01 (one) ; USNM 188005 , St . SA2-01 (one) ; USNM 188009 , St . SA2-01 (one) ; USNM 188012 , St . SA5-11 (one) ; USNM 88013 , St . SA5-14 (two) ; USNM 188024 , St . SA5-11 (three) ; USNM 188025 , St . SA2-01 (one) ; USNM 188027 , St . SA4-14 (two) ; USNM 188028 , St . SA5-14 (two) ; USNM 188029 , St . SA5-14 (one) ; USNM 188031 , St . SA2-01 (one) .

Type locality: West Atlantic , off Florida .

Diagnosis: First three pairs of parapodia with pseudocompound bidentate falcigers with moderately long pointed hoods; ventral cirri subulate on first three chaetigers; subacicular hooks starting from chaetiger 9; branchiae absent; frontal lips spherical; eyes absent; peristomial cirri present.

Description: Largest syntype ( MCZ 766) lacking posterior part of the body and poorly preserved. Another syntype ( MCZ 857) lacking both anterior and posterior parts, making it unidentifiable. Two syntypes ( MCZ 857) consisting of ten and 13 chaetigers, both 0.4 mm wide. Body width of studied specimens varying from 0.3 to 0.8 mm. Two complete specimens were found in additional non-type material: larger complete specimen consisting of 129 chaetigers 62 mm long and 0.5 mm wide, smaller complete specimen with 75 chaetigers 0.3 mm wide. Body of preserved specimens yellowish to pinkish, lacking colour pattern.

Prostomium anteriorly rounded with spherical frontal lips ( Fig. 14B ). Palps reaching chaetiger 1; lateral antennae to chaetiger 4 (chaetigers 3–8), median antenna to chaetiger 2 (chaetigers 1–3) ( Fig. 14A, B ). Ceratophores of lateral antennae with four (between three and five) rings without lateral projections. Nuchal grooves slightly curved; eyes absent. Peristomial cirri shorter than peristomium, tapering distally ( Fig. 14A ).

Anterior three pairs of parapodia modified, projecting lateroventrally and directing anteriorly ( Fig. 14B, E, F ). Prechaetal lobes rounded, postchaetal lobes triangular, present on first eight chaetigers (chaetigers 4 or 5 in the smallest specimens), later reduced and almost invisible. Ventral cirri subulate on anterior three pairs of parapodia, later replaced by dropshaped glandular pads ( Fig. 14B ).

First two pairs of parapodia with one simple capillary chaeta and three or four pseudocompound bidentate falcigers ( Fig. 14E ). Third pair of parapodia with one dorsal simple capillary chaeta, two pseudocompound falcigers, and two ventral simple tapering chaetae ( Fig. 14F ). All falcigers clearly bidentate with paired moderately long pointed hoods ( Fig. 14I ). Starting from the fourth chaetiger all parapodia with simple limbate chaetae arranged in two fascicles: dorsal limbate chetae long and slender, ventral limbate chaetae short and stout. Bidentate subacicular hooks starting from chaetiger 9 in all specimens examined ( Fig. 14G, H, K ). Pectinate chaetae very thin and transparent, with about 14–16 teeth ( Fig. 14J ). Neuroaciculae pale, up to two per parapodium.

Branchiae absent. Mandibles thin with relatively wide carriers. Calcareous cutting plates with one distinct indentation ( Fig. 14D ). Maxillae weakly sclerotized. Maxillary formula (based on one specimen): Mx I = 1 + 1; Mx II = 8 + 10; Mx III = 10 + 0; Mx IV = 7 + 14; Mx V = 1 + 1 ( Fig. 14C ).

Pygidium with two pairs of anal cirri; dorsal pair longer than ventral one. Tubes cylindrical, longer than their inhabitants, with parchment-like inner layer and outer layer of mud and scattered shells of foraminifers.

Remarks: Diopatra (Paradiopatra) was described by Ehlers (1887) as a subgenus for Diopatra lacking branchiae, but having similar tubes, especially characteristic for Diopatra incrusted by pieces of shells, algae, and other foreign particles. The shape of Diopatra tubes is very specific: foreign particles are attached to the tube forming a structure similar to a bottle brush. Although Fauchald (1982) reported that the tubes of type specimens of P. fragosa are similar to those of D. ornata , they are covered by scattered dead foraminiferans that are not arranged in specific pattern, as in Diopatra .

Fauchald (1982) reported four pairs of subulate ventral cirri in P. fragosa . We re-examined all type specimens and found only three pairs of ventral cirri that correspond well to the original description and drawings ( Ehlers, 1887).

Paradiopatra fragosa resembles P. okai Imajima, 1999 in having bidentate falcigers, three pairs of modified parapodia, lacking branchiae, and with subacicular hooks starting from chaetiger 9. Paradiopatra fragosa differs from P. okai by lacking eyes, having spherical rather than ovoid frontal lips, and building muddy tubes incrusted by foraminifers rather than sandy tubes.

Distribution: West Atlantic from North Carolina to Florida; Grenada ( Fig. 15). Depth range 609–1054 m.

H I J K

PARADIOPATRA ABYSSALIS ( IMAJIMA, 1999)

Figures

Figure 7. Different types of chaetae in Eunicidae (A) and Onuphidae (B–P): A, compound falciger; B, simple capillary chaeta; C, unidentate pseudocompound falciger; C, bidentate pseudocompound falciger; D, tridentate pseudocompound falciger; F, pseudocompound tapering chaeta; G, simple tapering chaeta; H, recurved falciger; I, pectinate chaeta; J, limbate chaeta; K, spiniger; L, pseudocompound limbate chaeta; M, large median tridentate hook; N, O, bidentate subacicular hooks; P, distally entire subacicular hook.

Figure 12. Scheme of Paradiopatra anterior region and jaw apparatus: A, dorsal view; B, ventral view; C, maxillae, dorsal view; D, mandibles, ventral view.

Figure 13. Scheme of Paradiopatra body plan showing distribution of different types of parapodia and chaetae along the body.

Figure 14. Paradiopatra fragosa (MCZ 1017): A, anterior end, dorsal view; B, anterior end, ventral view; C, maxillae; D, mandibles; E, parapodium of chaetiger 1, anterior view; F, parapodium of chaetiger 3, anterior view; G, parapodium of chaetiger 9, anterior view; H, parapodium of chaetiger 31, anterior view; I, bidentate pseudocompound falciger from chaetiger 1; J, pectinate chaeta from chaetiger 15; K, subacicular hook from chaetiger 31.