Diopatra hannelorae, Steiner & Amaral, 2021

Seixas, Victor Corrêa, Steiner, Tatiana Menchini, Solé-Cava, Antônio Mateo, Amaral, Antonia Cecília Zacagnini & Paiva, Paulo Cesar, 2021, Hidden diversity within the Diopatra cuprea complex (Annelida: Onuphidae): morphological and genetics analyses reveal four new species in the south-west Atlantic, Zoological Journal of the Linnean Society 191, pp. 637-671 : 653-658

DIOPATRA HANNELORAE STEINER & AMARAL SP. NOV.

( FIGS 14–18)

lsid:zoobank.org:act: 8107C875-C380-4EAA-9F36- A07DC0B4C4AF

Holotype: ZUEC POL 101 (jaws removed); 23°46’17’’S; 45°24’09’’W; intertidal, Brazil, São Paulo State, São Sebastião, Arrastão Beach (Centro Náutico); 6.III.1989.

Paratypes: ZUEC POL 2949 (one spec.); 23°46’17’’S; 45°24’09’’W; intertidal, Brazil, São Paulo State, São Sebastião, Arrastão Beach ( Centro Náutico ); 6.III.1989 . ZUEC POL 2950 (four spec. numbers 36, 39, 40, 44) , ZUEC POL 2951 (four spec. numbers 17 jaws removed, 24, 25, 41) , ZUEC POL 2952 (four spec. numbers 18, 43 jaws removed, 47, 54) , ZUEC POL 2953 (three spec. numbers 15, 42, 45); 32°03’29’’S; 51°59’40’’W; intertidal; Brazil, Rio Grande do Sul State, São José do Norte, Base do Molhe Leste ; 28.I.2002; coll. P. Marsh. ZUEC POL 10688 (one spec.); 27°29’S; 48°38’W; intertidal; Brazil, Santa Catarina State, Biguaçu ; 19.XI.2009; coll. G. F. Alves. ZUEC POL 10732 (one spec.); 27°31’S; 48°31’W; intertidal; Brazil, Santa Catarina State, Florianópolis, Ponta do Forte ; 07.IX.2009; coll. G. F. Alves.

O t h e r m a t e r i a l: Z U E C P O L 3 3 4 6 (t w o s p e c.); 32°03’29’’S; 51°59’40’’W; intertidal; Brazil, Rio Grande do Sul State, São José do Norte, Base do Molhe Leste ; 28.I.2002; coll. P. Marsh (specimens 38 and 46–dried) .

Diagnosis: MPs with different sizes and acicular lobe with a (slender) projection. Bidentate and hooded HO, PA in similar positions (except HOL, without PA) in first parapodium; PA varying in position in other MP; HOL more robust than others HO. Pectinate chaetae of anterior region with six to ten large and narrow teeth in the same parapodium; posterior region with uniform pectinate chaetae with about 15 straight teeth, being smaller in one of the laterals.

Size and shape: Holotype 83 mm long, 4.5 mm wide, 101 chaetigers, incomplete. Paratype series 17 to 91 mm long, 2.5 to 7 mm wide and 25–154 chaetigers. Longest specimen 91 mm long, 4.5 mm wide and 154 chaetigers. Widest specimen 30 mm long, 7 mm wide and 25 chaetigers. Body rounded in cross-section in first chaetigers and slightly flattened dorsoventrally in rest of body.

Colour: Fixed specimens with body ranging from intense brown along anterior and median region, mainly in fully bleached specimens. Scattered brown spots on prostomium, ceratophores, frontal and upper lips.

Prostomium, peristomium and appendages ( Fig. 14): Prostomium slightly conic on anterior margin, 1 to 1.5 twice as (holotype 1.2) longer as peristomium ( Fig. 14B). Ocellar spots absent; nuchal organ well defined, semicircular. Pyriform frontal lips, half to two-thirds length of prostomium (holotype half), almost juxtaposed and spaced from palps ( Fig. 14B–E). Well-defined upper lips, distal lobe well developed with rounded end; well-defined median section, sometimes covered by distal lobe. Lower lip in a halfmoon, with well-defined median section ( Fig. 14E). Base of median antenna shifted from centre to the base of prostomium, more spaced from lateral antennae than these in relation to palps ( Fig. 14D). Ceratophores of antennae with similar diameter, almost as long as prostomium; palpophores narrower. Rings well demarcated, median and palps with seven to nine rings, lateral eight to ten (holotype eight to nine); all with a distal ring two times longer than others, sometimes partially merged with the next. Ceratostyles and palpostyles, when complete, with acuminate end; when complete, median reaching chaetiger three to 11, lateral three to nine and palpostyles two to three. Peristomium as long as the following chaetigers. Peristomial cirri smooth, cirriform, half to two-thirds the length of prostomium, subdistally inserted. Segments after peristomium with equivalent lengths.

Parapodia ( Fig. 15): First four pairs of parapodia robust, with slightly different sizes, chaetiger one shorter, two, three and four slightly longer, and the following smaller. Cirriform dorsal cirrus, almost twice as long as ventral in first chaetiger, becoming longer until chaetiger four to five, with almost the times the length of ventral, decreasing thereafter. Cirriform ventral cirrus in first five chaetigers, rarely one transitional, pad-like from chaetiger six. Prechaetal fold evident in MP. Acicular lobe well developed, with a projection tapered in MP, rounded, decreasing gradually its length until appearance of subacicular hook ( Fig. 15D, E). Cirriform postchaetal lobe, as long as ventral cirrus, short in chaetiger seven and decreasing along rest of body. Branchiae from chaetiger five, rarely four (holotype five), present in chaetigers 45–63, depending on the size, being 38–50 spirals (holotype 43) and six to 13 single filaments (holotype ten). Branchiae in chaetiger five more robust, with eight to 15 spirals.

Chaetae of MP ( Fig. 16): First four chaetigers with HO and one to two thin, curved capillaries ( Fig. 14A); without transitional chaetigers. HO pseudocompound (except HOL), hooded, bidentate, with laterally directed teeth, pronounced curvature. HO with similar lengths in first chaetiger, HOs and HOm with similar length and width, HOi a little smaller and little shorter. In other MP HOs maintain its size, HOm and HOi a little shorter and narrow. Generally, one or two hooks of each type are present, with exception of the HOi, which are often found three. HOL more robust than others HO.

Chaetae of UP ( Fig. 17): Chaetiger five onward with up to 16 supracicular limbate chaetae with wide blade ( Fig.17A, B). Chaetigers five to 16–23 (holotype 19) with up to ten short infracicular limbate chaetae ( Fig. 17C, D). Subacicular bidentate hook with short hood, beginning in chaetiger 17–24 (holotype 17), with one or two transitional, with limbate chaetae; first one or two chaetigers with both teeth of equal size ( Fig. 17H), then directed both laterally, and basal more developed ( Fig. 17I). Pectinate chaetae little asymmetrical, from chaetiger six, about ten per parapodium; six to ten teeth in anterior parapodia ( Fig. 17E, F) and 17–26 teeth in the following ( Fig. 17G). Teeth of one lateral twice as long as the other lateral; teeth with unequal width in anterior chaetigers. Notopodial aciculae always fine, straight, five to ten per parapodium. MP with about five neuropodial aciculae in crossed position ( Fig. 17J); posterior region with four to five parallel aciculae ( Fig. 17K). All aciculae tapered distally and ventral one with smaller diameter.

Jaw apparatus ( Fig. 18): Larger specimens with beige to light brown jaws and darker sclerotized areas. Smaller specimens with dark beige jaws and brown maxillary carrier. Mandibles ranging from light beige to light brown. Sclerotized plates always darker. White calcareous cover of mandibles. Inner callus of MI at an obtuse angle to its above portion (arrow). MI slightly more than twice longer than plate of maxillary carrier (without free portion of carrier sclerotized plate). Teeth of MI to MIV pronounced, upturned. Right MII slightly larger than left. Attachment lamella of MIII triangular shape. External base of MIII upturned. Left MIV shorter than right, being this one the external and internal of similar sizes; inner arch little pronounced. Internal base of right MIV almost straight. Both MIV with an inner callus near internal base and attachment lamella covering all outer edge. Rounded outer lateral edge of MV and ‘L’-shaped in inner lateral edge. Maxillary formula: MI = 1 + 1, MII = 7–8 + 7–9, MIII = 6–9, MIV = 4–7 + 6–7, MV = 1 + 1. Mandibles (without calcareous cover) as long as MI + plate of maxillary carrier (without free portion of carrier sclerotized plate). Narrow calcareous cover, resistant to removal, projecting just beyond cutting plate, rounded edge.

Remarks: Pectinate chaetae showed different shapes, especially in anterior region, with teeth varying widely in width. In the posterior region this variation is not verified, being composed by many fine teeth in a uniform graduation in width of one lateral to the other.

Intraspecific variations: The largest specimen of the series has only 25 chaetigers and presence of the subacicular hook has not been observed, which means that in this species the subacicular hook may also begin after chaetiger 25.

Discussion: Diopatra hannelorae closely resembles D. m a r i n a e a n d D. v i c t o r i a e i n t h e g e n e r a l characteristics of the body, but D. hannelorae is a robust species with well-developed prostomial appendages and upper and lower lips. In addition, the most acuminate prostomium, the length of ceratophores, dorsal cirrus and the spacing between antennae and palps distinguish this species from D. marinae and D. victoriae . Although all HO are similar, the equivalent lengths in first parapodia characterize D. hannelorae . Also, pectinate chaetae have teeth of different widths in anterior parapodia, whereas in D. marinae and D. victoriae teeth have more uniform width. In relation to jaws, there are some characteristics that distinguish D. marinae and D. victoriae : MIII external base more upturned, right MIV almost without inner arch, practically rectilinear. Also, the calcareous cover of mandibles is short and with a rounded edge.

The three new species are compared with similar species that have large simple median hook without pseudoarticulation. Diopatra sugokai Izuka (1907) also differs from the three species by presenting a double postchaetal lobe. Diopatra hanleyi Paxton (1993) resembles D. marinae and D. victoriae in relation to the shape of the pectinate and teeth of the PH. However, this species has a striking pattern of coloration, with specific pigmentation, including in the dorsal and ventral cirrus and postchaetal lobe.

Occurrence: Intertidal; States of São Paulo (cities of São Sebastião and Santos), Santa Catarina (cities of

Florianópolis and Biguaçu) and Rio Grande do Sul (Rio Grande).

Etymology: The name is given in honour of Hannelore Paxton, polychaete expert of the family Onuphidae who has published important studies on taxonomy and phylogeny.

DIOPATRA PECTINICONICUM STEINER & AMARAL