Diopatra tuberculantennata Budaeva & Fauchald, 2008, new species
Creators: name: Budaeva, Nataliya
name: Fauchald, Kristian
Publisher: name: Zenodo
Year: 2008
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Eunicida
Onuphidae
Diopatra
Diopatra tuberculantennata

description: Diopatra tuberculantennata, new species
Figs. 1–7
Diopatra cuprea: Fauchald, 1980: 797 –829 (in part).
Type material: USNM 1112433, St. CBC- 2006-34 (holotype); USNM 1112434, St. CBC- 2006-31 (6 paratypes); USNM 1112435, St. CBC- 2006-32 (1 paratype); USNM 1112436, St. CBC- 2006-34 (1 paratype); USNM 1112437, St. CBC- 2006-39 (1 paratype); USNM 1112438, St. CBC- 2006-41 (3 paratypes); USNM 1112439, St. CBC- 2006-43 (3 paratypes).
Non type material examined: USNM 61213, St. CB-01 (2); USNM 61214, St. CB-02 (1); USNM 61215, St. CB-06 (1); USNM 61216, St. CB-11 (1); USNM 61217, CB-16 (1); USNM 61218, St. CB-28 (2); USNM 61219, St. CB-34 (2); USNM 61223, St. CBC-F-28 (1); USNM 61222, St. CBC-F-09 (1); USNM 1112440, St. CBC-2006-01 (1); USNM 1112441, St. CBC-2006-03 (1); USNM 1112442, St. CBC-2006-05 (1); USNM 1112443, St. CBC- 2006-07 (1); USNM 1112444, St. CBC- 2006-10 (1); USNM 1112445, St. CBC- 2006-11 (1); USNM 1112446, St. CBC- 2006-12 (1); USNM 1112447, St. CBC- 2006-13 (1); USNM 1112448, St. CBC- 2006-16 (1); USNM 1112449, St. CBC- 2006-17 (1); USNM 1112450, St. CBC- 2006-21 (2); USNM 1112451, St. CBC- 2006-23 (3); USNM 1112452, St. CBC- 2006-26 (1); USNM 1112453, St. CBC- 2006-28 (1); USNM 1112454, St. CBC- 2006-29 (1); USNM 1112455, St. CBC- 2006-31 (23); USNM 1112456, St. CBC- 2006-32 (2); USNM 1112457, St. CBC- 2006-37 (1); USNM 1112458, St. CBC- 2006-39 (1); USNM 1112459, St. CBC- 2006-41 (4); USNM 1112460, St. CBC- 2006-43 (3); USNM 1112461, St. CBC- 2006-51 (1); USNM 1112462, St. CBC- 2006-52 (3).
Comparative material examined: Diopatra dubia Day, 1960, BMNH-1961.20.1-2, st. FAL 237 (2 paratypes); BMNH-1961.9.930-933, st. FAL 309 (4); ZMUC: “Galathea”, st. 134 (7), “Galathea”st. 155 (1), “Galathea”st. 167 (1). Diopatra angolensis Kirkegaard, 1988, ZMUC-Pol-1506, “Galathea”, st. 117 (holotype).
Type locality: Belize, Carrie Bow Cay, 16.8027° N, 88.0819° W, 0.5 m. Coordinates of all stations are given in Table 1, map of stations is shown in Figure 1.
Diagnosis: Palpophores and antennophores with large lateral projections on median rings; first five chaetigers with bidentate pseudocompound hooks; hoods moderately long and pointed; nuchal organs forming almost closed circles; very large sensory papillae irregularly distributed on antennostyles and on frontal, upper and lower lips.
Description: Holotype complete specimen with 93 chaetigers, 43 mm long, 1.3 mm wide (at chaetiger 10, without parapodia) (Fig. 2 A–C). Complete specimens range from 0.6 mm width (41 chaetiger) to 1.3 mm width (93 chaetigers). The greatest width of incomplete specimen is 2 mm. Anterior end of body including first five chaetigers cylindrical, median and posterior parts of body dorsally flattened. Living specimens whitish dorsally, light rose-colored laterally and ventrally with scattered small brown spots, similar spots also on antennae and palps. Brown band across chaetiger 5 (retained in most of preserved specimens). Some ethanolstored specimens with brown pigmentation dorsally in branchial region and brown antennae, in most cases of the same color as body pigmentation. Staining with Methylene Blue yielding following, distinct patterns: Each chaetiger in posterior 1/3 of body with wide, dark blue dorsal and ventral glandular cross-bands. Dorsal cirri, frontal, upper and lower lips and palpostyles also staining dark blue; remaining body pale blue.
Prostomium with subulate frontal lips (Figs. 2 A, 3A, K). Upper lips elongate; lower lip with median incision. Palps of holotype reaching chaetiger 2, varying in other specimens from chaetigers 1–3. All antennae about equal in length, reaching chaetiger 7 in holotype; in other specimens reaching chaetigers 4–13. Length of antennae quite variable, slightly depending on size of specimen (Fig. 4). Palpophores of holotype with five rings; in other specimens with up to six rings. Antennophores of holotype with eight rings; in other specimens with 4–8 rings. Both palpophores and antennophores with large lateral projections on median rings (Figs. 2 A, B, 3A). Palpophore projections usually on second ring, rarely on third. Second and third rings of holotype lateral antennophores with projections; in other specimens projections on second to fourth rings. Projections of median antennophore on second to fourth rings in holotype; in other specimens projections present from first to fifth rings. Palps, antennae, frontal, upper lips and anterior margin of lower lip covered by randomly distributed large sensory papillae (Fig. 3 B–D, K). Nuchal grooves curved, forming nearly circle in adults (Fig. 2 B). One pair of small brown eyespots present near base of lateral antennae. Peristomium as long as first chaetiger. Peristomial cirri about as long as peristomium.
First five parapodia projecting laterally, directing slightly anteriorly but not enlarged. More posterior parapodia similar; ridge-shaped and located laterally. Prechaetal lobes rounded, postchaetal lobes a low ridge covering bases of chaetae, but with distinct median subulate projection, gradually decreasing in size towards posterior region but still distinct at posterior end of the body (Fig. 3 L, M). First five chaetigers with small ventral protrusions at base of postchaetal lobes (Fig. 2 F). Ventral cirri cirriform on first five chaetigers in holotype (Fig. 2 A), in other specimens varying between four and five chaetigers (Fig. 3 F), apparently almost independently of size of specimens (Fig. 5).
Anterior projecting parapodia (Figs. 2 F, 3M) with 1–2 upper simple chaetae and 4–5 bidentate pseudocompound hooks (Figs. 2 N, 3H). Hooks with moderately long pointed hoods and two rows of blunt small spines along their shafts. Remaining parapodia with mainly strongly serrated limbate chaetae (Figs. 2 O, 3E). Pectinate chaetae flat with straight distal margins, each has 18–20 teeth. Pectinate chaetae from chaetiger 6 in holotype, from chaetigers 5–6 in other specimens (Figs. 2 L, 3I), One unusual specimen had pectinate chaeta with nine very long teeth in second parapodia (Figs. 2 M, 3J). Starting from chaetiger 9 in holotype, and from chaetigers 7–12 in other specimens, lower limbate chaetae replaced by thick bidentate subacicular hooks (Fig. 2 G, H, J, K) with very thin translucent guards. Start of subacicular hooks slightly positively linked to increasing size of specimens (Fig. 5).
Branchiae with up to five spiraled whorls of relatively short filaments (Fig. 2 H, I) starting from chaetiger 5 (Figs. 2 B, 3G) and continuing to chaetiger 34 in holotype, varying from chaetigers 14–37 in other specimens. Position of the last branchia strongly correlated with width of specimen (Fig. 5). Best developed branchiae present on chaetigers 6–7; branchiae becoming gradually reduced towards posterior chaetigers, but almost all branchiae with several filaments; only last 1–2 pairs single.
Mandibles weakly sclerotized with calcareous distal cutting plates (Fig. 2 E). Distal indistinct indentations along edge of cutting plates present. Sclerotization of maxillae invisible, appearing white, thick and calcareous (Fig. 2 D). Maxillary formula (based on five specimens): Mx I = 1 + 1; Mx II = 8–9 + 9–10; Mx III = 7–8 + 0; Mx IV = 6–7 + 7–9; Mx V = 1 + 1.
Pygidium with four anal cirri, ventral longer than dorsal ones (Fig. 2 C). Tube, as characteristic for Diopatra, cylindrical and covered with debris, mostly parts of sea grass and pieces of shells attached on all sides of tube; permanently buried part of tube thin-walled and covered by fine sand.
Intraspecific variability of the main morphological characters is shown in Table 2.
Remarks: Diopatra dubia Day, 1960, D. papillata Fauchald, 1968 and D. angolensis Kirkegaard, 1988 are the three other species in the genus known to have lateral projections on the ceratophores (Tab. 3). The new species can be distinguished from the other species by having scattered large sensory papillae on all styles of the prostomial appendages, frontal and upper lips. Diopatra tuberculantennata differs from D. dubia in having subulate frontal lips instead of partly fused spade-shaped ones; the nuchal grooves form almost circle instead of being crescentic; the antennae are relatively longer, reaching chaetiger 8 instead of chaetigers 2– 3; the pseudocompound hooks have moderately long, pointed hoods on the first five chaetigers instead of having hooks with very long hoods in the first four chaetigers, and in having, rather than lacking eyes. From D. angolensis, D. tuberculantennata can be distinguished by the size and distribution of the lateral projections on the ceratophores. Diopatra angolensis has very small lateral projections on the three basal rings of the antennophores, while D. tuberculantennata has large projections on the median rings on both antennophores and palpophores; the basal rings of the ceratophores are always smooth. In addition, D. tuberculantennata has fewer branchial chaetigers (not more than 32 instead of 55) and the subacicular hooks start from chaetiger 9 (7–12) rather than from chaetiger 13 (14). Diopatra angolensis has long hoods on the anterior pseudocompound hooks instead of the moderate ones present in D. tuberculantennata. From D. papillata, D. tuberculantennata differs in having five anterior chaetigers with pseudocompound hooded hooks instead of three such chaetigers.
Character D. dubia Day, 1960 D. papillata Fauchald, D. angolensis Kirke- D. tuberculantennata
1968 gaard, 1988 sp. nov. Frontal lips spade-shaped, fused subulate subulate subulate Eyes absent absent absent present Shape of nuchal grooves crescentic? forming nearly circle forming nearly circle Size of sensory papillae small? small large Locality off South West Africa upper end of the Gulf off South West Africa, Belize, east of Dan-
of California Angola griga
Depth, m 50–412 73–110 27–75 0–2 Biological notes: Five 28-chaetiger juveniles about 3 mm long and 0.3 mm wide were found inside the parental tube of one specimen (Fig. 6 A, B). All juveniles have well developed prostomial appendages with sensory papillae (Fig. 6 C, H). Antennophores have 3–4 rings with small lateral projections. Palpophores have 3 rings with tiny projections on the middle rings (Fig. 6 D, E, G). Nuchal grooves are slightly crescentic (Fig. 6 G, I). Distribution of chaetae is the same as in adults except that the pseudocompound hooded hooks are present on first four rather than on five chaetigers as in the adults (Fig. 6 F). Peristomial cirri are present. Provisional larval chaetae are absent. Spiraled branchiae with up to four filaments start from chaetiger 5 and are present on six chaetigers.
The complete development from egg to 40-chaetiger larva has been described for only one member of the genus Diopatra, D. marocensis Paxton et al., 1995 (Fadlaoui et al. 1995). As D. marocensis, D. tuberculantennata broods larvae and juveniles, with direct development inside the parental tube and thus belongs to group I designated by Paxton (1993). Although 28-chaetiger juveniles of D. marocensis are slightly larger (width: 0.49 mm, length: 4 mm), they represent an earlier stage of development than in the new species in that provisional chaetae are still present, peristomial cirri are absent and branchiae appear only on two chaetigers. This difference could be related to differences in a brood size. Size of adults is relatively similar in the two species but brood size of D. marocensis is 20–100 (Fadlaoui et al. 1995) whereas we found only 5 juveniles inside the tube of D. tuberculantennata.
Twelve specimens with regenerating anterior ends of the body were found in the examined material. Together they represent five consecutive stages of regeneration (Fig. 7). Different stages were recognized based on degree of development of regenerated part of the body, e.g. number of chaetigers and presence of chaetae.
Stage I: Short round prostomium with antennae represented by five tubercles and mouth aperture starting to form on the anterior end (where the worm was cut, Fig. 7 A, B, I).
Stage II: Regenerating anterior end starting to differentiate ventrally into prostomium, peristomial ring and four chaetigers with parapodia visible as ventro-lateral bulges; prostomial appendages increasing in length to form five short cylindrical bosses; mouth aperture increasing in size, triangular in shape; frontal lips appear as two weakly developed, but distinct expansions (Fig. 7 C, D, J).
Stage III: Prostomium, peristomium and five chaetigers distinctly separated from each other; prostomial appendages becoming conical with two-ringed ceratophores and sensory papillae present both on palpostyles and antennostyles; frontal lips appear as hemispherical tubercles; upper lips forming two well separated spherical structures, lower lip present as a fold behind upper lips; nuchal grooves visible as thin almost straight lines widely separated middorsally; peristomial cirri absent; parapodia trilobate without chaetae, gradually decreasing in size towards the posterior end of the regenerating part (Fig. 7 G, H).
Stage IV: Segmentation more marked, but border between prostomium and peristomium on the dorsal side still absent. All prostomial styles longer and covered by well developed sensory papillae; ceratophores have three rings; frontal lips becoming more elongate; lower lip still not separated from peristomium; nuchal grooves becoming more curved and thicker; peristomial cirri visible as bulges on the dorsal side; first 1–3 curved chaetae, resembling provisional chaetae of D. marocensis (Fadlaoui et al. 1995), appear in anterior parapodia of regenerating part (Fig. 7 E, K–M).
Stage V: Segmentation well developed, prostomium, peristomium and seven following chaetigers separated from each other; all prostomial structures present and have shape similar to the normal condition, but width of regenerating part only about 1/2 the width of the normal segments of the non-regenerating body. Each antennophore has four rings with small lateral projections on the second and third rings; lower lip distinct, nuchal grooves crescentic, wide straps; eyespots present; spiraled branchiae with up to 4 filaments appear starting from chaetiger five; ventral cirri cirriform on first four chaetigers; pseudocompound bidentate hooded hooks present in first four chaetigers (Fig. 7 F, N, O).
The consecutive stages of regeneration imitate the ontogenesis in the genus Diopatra, but with some differences. In the development of D. marocenis palpostyles and antennostyles form first, followed by the frontal lips. Peristomial cirri appear at a very late (more than 38-chaetiger) stage when juveniles leave the parental tubes (Fadlaoui et al. 1995). A similar pattern of development of the prostomium and peristomium was shown in the present study. Provisional curved chaetae that are characteristic of all Diopatra larvae were found in the first and second chaetigers of a regenerating specimen (stage IV). At stage V the provisional chaetae were replaced by pseudocompound hooded hooks. The early appearance of segmentation and chaetae in ontogenesis, rather than early development of prostomial appendages is the main difference between ontogenesis and regeneration.
The ability to regenerate the anterior part of the body has been described in onuphids but only for three species from the genus Diopatra: D. amboinensis Audouin et Milne-Edwards, 1833 (Pflugfelder 1929 in Hyman 1940); D. dexiognatha Paxton & Bailey-Brock, 1986 (Bailey-Brock 1984 as D. leuckarti Kinberg, 1865; Paxton & Bailey-Brock 1986) and D. neapolitana (Delle Chiaje, 1841) (Bely 2006).
The current species shows an ability to develop a new prostomium, peristomium and several chaetigers even in a case when more than 9-10 anterior chaetigers had been lost: we found regenerating specimens with subacicular hooks that normally start from chaetiger 9 in the first to the fourth chaetiger.
Although posterior segment regeneration is very common among polychaetes (Bely 2006) we did not find specimens showing this state in our material.
Distribution: Caribbean Sea, East off Dangriga, Belize. Depth 0.5– 2 m. Usually on the border between free sand and areas covered with Thalassia.
Etymology: The specific name, tuberculantennata, refers to the unusual surface of antennae with its randomly dispersed large sensory papillae, each of which has a tubercular shape.
description: Published as part of Budaeva, Nataliya & Fauchald, Kristian, 2008, Diopatra tuberculantennata, a new species of Onuphidae (Polychaeta) from Belize with a key to onuphids from the Caribbean Sea, pp. 29-45 in Zootaxa 1795 on pages 30-41, DOI: 10.5281/zenodo.182638