Diopatra cryptornata, Fauchald, Kristian, Berke, Sarah Kosting & Woodin, Sarah Ann, 2012

Fauchald, Kristian, Berke, Sarah Kosting & Woodin, Sarah Ann, 2012, Diopatra (Onuphidae: Polychaeta) from intertidal sediments in southwestern Europe, Zootaxa 3395, pp. 47-58 : 52-54

Diopatra cryptornata , new species

Plate 2c–e

Material examined: USNM 112825, Obidos, Portugal, Spring 2008, coll. F. Lima (holotype; (position, ca 39°41’N, 9°21’E), USNM 1180239, Huelva, Spain, 1 July 2006 (1); USNM 112814, Obidos, Portugal, 15 May 2006 (1 paratype); USNM 112824, Obidos, Portugal, Spring 2008, coll. F. Lima (1 paratype);; USNM 112826,.Obidos, Portugal, Spring 2008, coll. F. Lima (1 paratype); USNM 112827, Obidos, Portugal, Spring 2008, coll. F. Lima (1 paratype) USNM 112836, Obidos, Portugal, Spring 2008, coll. F. Lima (1 paratype); USNM 118237, Obidos, Portugal, Spring 2008, coll. F. Lima (1 paratype); USNM 118238, Obidos, Portugal, Spring 2008, coll. F. Lima (1 paratype); USNM 112839, Obidos, Portugal, Spring 2008 (1 paratype).

Diagnosis: Upper lips without median papilla and ridge. Paired dorsal papillae from chaetigers 7 or 8 through chaetigers 33–38. Postchaetal lobes of anterior modified chaetigers with a single elongated papilla. First four chaetigers with falcate pseudocompound hooks; hoods short and bluntly pointed. Subacicular hooks present from chaetigers 16–19 (chaetiger 16 in holotype). Pectinate chaetae with 5–7 teeth throughout body (as far as known).

Description: All specimens posteriorly incomplete. Anterior end including first five chaetigers tilted slightly dorsally, dorsum convex, ventrum flattened, narrowing from anterior end to segment 6. Body abruptly wider at segment 6. Cross-section of rest of body basically rectangular with dorsum slightly convex. Central ventrum flattened with enormously expanded glandular bases of ventral cirri forming curved outer surfaces. Anteriormost parapodia directed anteriorly and ventrally, other modified parapodia gradually shifting to fully lateral positions and directions. Anterior dorsum dark brownish purple, fading from about chaetiger 10 posteriorly to narrow bands on either side of the intersegmental grooves. Prostomium dark brown, including antennophores and bases of frontal lips; ceratostyles and palpostyles and tips of frontal lips light, brownish yellow. Peristomial cirri and dorsal cirri light colored. Ventrum of five first chaetigers irregularly dark brown with light colored ventral cirri. Modified parapodia irregularly pigmented with brown.

Prostomium (Plate 2c) rounded in dorsal view with antennae and palps forming a posterior curved line. Palps reaching chaetiger 2 in holotype, in other specimens reaching chaetigers 2–4. Lateral antennae reaching chaetiger 10 in holotype; truncated in some specimens, when intact reaching chaetiger s 8 to 15. Median antenna reaching chaetiger 12 in holotype; in other specimens reaching chaetigers 8–19. Palpophores of holotype with 12 rings; other specimens with 8 to 12 rings. Antennophores of holotype with 12 rings, other specimens with between 8 and 12 rings. Rings smooth in all anterior appendages. Nuchal grooves and eyes not seen. Peristomium dorsally slightly narrower than first chaetiger; laterally expanding so at junction with first chaetiger peristomium distinctly wider than first chaetiger. Peristomial cirri about twice as long as peristomial length. Frontal lips subulate; upper lips (Plate 2d) separated medially, each lip a transverse cushion with a thick medial papilla. Lateral lips low folds, anteriorly tucked under paired upper lips and ventrally fused to distalmost end of upper lips. Lower lips a thick curved structure divided into three parts; two lateral parts thick, increasingly flattened towards lateral side and directly attached to lateral lips; median section quadrangular or rectangular.

A pair of white papillae present dorsally on each segment from chaetiger 7 through end of fragments. Papillae located somewhat lateral to midline of each segment in first three to five papillated segments. More posterior papillae located roughly mid-way between midline and parapodial bases forming distinct longitudinal lines; most papillae digitiform, but especially from about chaetiger 20 may be spherical or clavate suggesting partial retractability. Last pair of papillae present on chaetiger 33 in holotype. In other specimens papillae present from chaetiger 7–9 to end of fragments (roughly segments 33–35), except in specimen from Huelva in which very small papillae are present to chaetiger 38.

First parapodia (Plate 2e) located ventrally and projecting laterally and slightly anteriorly. Second to fifth parapodia increasingly lateral in position projecting more directly laterally. Main prechaetal lobes distally rounded covering only dorsalmost fascicle of chaetae; three smaller fascicles of chaetae each bordered by low, oblique prechaetal lobes. Main postchaetal lobe triangular in first parapodia, covering upper chaetae. Postchaetal lobes becoming relatively low ridges with projecting subulate, median papilla. In other modified parapodia. Parapodia shifting dorsally from chaetiger 6 becoming increasingly short conical structures directed dorsally. Prechaetal lobes obliquely rounded with high end dorsally; covering increasingly three lower fascicles as these fuse into single major fascicle. From chaetiger 6 to about chaetiger 20 postchaetal lobes with a basal, low ridge, with a distinct median lobe projecting beyond chaetae; dorsal chaetae shifting gradually in position to emerging along dorsal edge PLATE 2. Diopatra marocensis Paxton et al 1995 ; USNM 17584, paratype

a. dorsal view of anterior of small specimen showing prostomium with palpophores and antennophores removed to show horseshoe pattern of placement plus peristomium with peristomial cirri.

b. ventral view of anterior of small specimen showing upper and upper lips and lower external lips

Diopatra cryptornata USNM 112825, holotype

c. dorsal view of anterior of large specimen showing prostomium with palpophores and antennophores with proximal rings plus peristomium with peristomial cirri.

d. ventral view of anterior of large specimen showing upper and upper lips and lower external lips.

e. anterior view of parapodium of chaetiger 1 showing dorsal and ventral cirri, prechaetal lobes with distal ear-shaped extension; the upper edge of the acicular lobe and the extended tapering section of the postchaetal lobe.

of parapodia with median lobe shifting to a position between dorsal chaetal fascicle and remaining ventral chaetae. Median lobe increasingly tapering from a wide base; gradually decreasing in size towards posterior region but still distinct at end of all fragmentary specimens. Ventral cirri subulate on first four chaetigers, ear-shaped in chaetiger 5 becoming a large, flattened glandular structure curving around lower lateral side of body covering about 1/3 of total width of ventrum from chaetiger 6.

Anterior modified parapodia with 3–4 upper simple chaetae and 6–8 falcate pseudocompound hooks in lower fascicles. Hooks with short, bluntly pointed hoods and smooth shafts. Remaining parapodia mainly with strongly serrated limbate chaetae. Pectinate chaetae flat with straight distal margins, each with six coarse teeth in all chaetigers. Pectinate chaetae first present from chaetiger 6 in holotype, and from chaetigers 5–6 in other specimens. Starting from chaetiger 16 in holotype, and from chaetigers 17–19 in other specimens, lower limbate chaetae replaced by paired thick bidentate subacicular hooks with very thin translucent guards. One hook located at lower edge of chaetal fascicle and parallel to lower chaetae; second hook originating at about same location in parapodia, but directed distinctly ventrally; second hook located in front of inflated bases of ventral cirri; usually considerably larger than first hook.

Branchiae with more than 10 spiraled whorls of long filaments present from chaetiger 4 or 5 continued to end of all fragments. Best developed branchiae present on chaetigers 6–7; branchiae becoming gradually reduced but with several filaments at end of fragments.

Mandibles well sclerotinized with partially calcareous distal cutting plates. Distal indentations along edge of cutting plates distinct. Maxillae heavily sclerotinized; teeth flattened and triangular. Maxillary formula (based on one paratype): Mx I = 1 + 1; Mx II = 7 + 7; Mx III = 7+ 0; Mx IV = 7 + 9; Mx V = 1 + 1.

Tube cylindrical and covered with debris, mostly sea grass fragments and pieces of shells attached on all sides; permanently buried part of tube thin-walled and covered by fine sand.

Etymology. The species is named for the presence of the paired dorsal papillae, well hidden under the large and bushy branchiae (cryptos – hidden; ornata- ornamented).

Discussion. Two features appear to make Diopatra cryptornata unique. The dorsal papillae have not been mentioned for any species of Diopatra as far as we can determine. In addition, all species of Diopatra described so far have at least some bidentate or tridentate pseudocompound hooks. In this species all hooks are falcate. Paired subacicular hooks appear to be common among species of Diopatra ; at least all three species treated in this paper have them.

Geographical distribution. Diopatra cryptornata is known from two localities, Huelvas, Spain, west of Gibraltar, and the type locality, Obidos, Portugal.