Diopatra victoriae, 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 : 647-652

DIOPATRA VICTORIAE STEINER & AMARAL SP. NOV.

( FIGS 6–10, 12)

lsid:zoobank.org:act: D6400A96-84B8-4228-976F- 80F75F2EE60E

Holotype: ZUEC POL 2966 ; 23°30’10’’S; 45°08’10’’W; intertidal, Brazil, São Paulo State, Ubatuba, Lázaro

Beach; 19.VIII.2001; coll. P. Marsh and C.M. Voloch (specimen 49).

Paratypes: ZUEC POL 2962 (four spec. – 10 and 52 jaws removed, and 53, 57) , ZUEC POL 2963 (one spec. number 16) , ZUEC POL 2964 (one spec. number 2, jaws removed) , ZUEC POL 12492 (one spec. number 3, jaws removed); 23°30’10’’S; 45°08’10’’W; intertidal; Brazil, São Paulo State, Ubatuba, Lázaro Beach ; 18.VIII.2001; coll. P. Marsh and C. M. Voloch. ZUEC POL 2965 (one spec. number 51, jaws removed); 23°30’10’’S; 45°08’10’’W; intertidal; Brazil, São Paulo State, Ubatuba, Lázaro Beach ; 19.VIII.2001; coll. P. Marsh and C. M. Voloch. ZUEC POL 2968 (one spec. number 33); 24°00’25’’S; 46°16’07’’W; intertidal; Brazil, São Paulo State, Guarujá, Astúrias Beach ; 20.VII.2001; coll. P. Marsh. ZUEC POL 2969 (two spec. number 35 jaws removed, and number 34); 24°00’25’’S; 46°16’07’’W; intertidal; Brazil, São Paulo State, Guarujá, Astúrias Beach ; 10.VIII.2002; coll. P. Marsh. ZUEC POL 2970 (two spec. number 12 jaws removed, and number 50 – partially dried); 24°00’25’’S; 46°16’07’’W; intertidal, Brazil, São Paulo State, Guarujá, Astúrias Beach ; 09.VIII.2002; coll. P. Marsh.

Other material: ZUEC POL 98 (one spec. jaws removed); 23°21’23’’S; 44°51’24’’W; intertidal; Brazil, São Paulo State, Ubatuba, Fazenda Beach ; 9. V.2001; coll. A. Cecília Z. Amaral’s team. ZUEC POL 2955 (six spec.); 23°21’23’’S; 44°51’24’’W; intertidal; Brazil, São Paulo State, Ubatuba, Fazenda Beach ; 9. V.2001; coll. A. Cecília Z. Amaral’s team (jaws removed from one large specimen; three are younger).

Diagnosis: MPs with similar sizes and acicular lobe with a (slender) projection. Bidentate and hooded HO, PA in different positions (except HOL, without PA) in first parapodium; PA varying in position in other MP; HOL more robust than others HO. Pectinate chaetae slightly asymmetrical, with 17–26 teeth. Inner callus of MI in a right angle to its above portion. MIId with a convex curvature projected backwards. MIV compressed laterally; inner arch of MIVd more pronounced; internal base of MIVd curved and narrow.

Size: Holotype 225 mm long, 9 mm wide, 282 chaetigers, complete. Paratype series 25 to 138 mm long, 2 to 9 mm large, 58 to 150 chaetigers, all incomplete. Widest specimen 70 mm long, 9 mm wide, 74 chaetigers.

Jaw apparatus ( Fig. 12): Colour light to dark brown; sclerotized plates darker, almost black in some specimens. Shaft of mandibles light to dark brown. Calcareous cover of mandibles white. Inner callus of MI forming a right angle to its above portion (arrow). MI twice longer than plate of maxillary carrier (free portion of carrier sclerotized plate not included in measure). Prominent and generally sharp teeth of MII to MIV; basal one, of MII and MIII, rounded. MII slightly compressed laterally. Right MII slightly larger than left, external base with small convex curvature projected backwards (arrow). Basal tooth of left MII connected with internal base (arrow) by a ridge, forming a basal callosity. Attachment lamella of MIII triangular shape. Left MIV shorter than right, having external base larger than internal base; inner arch of right MIV pronounced. Internal base of right MIV slightly narrow and curved. Both MIV with an inner callus near internal base and attachment lamella covering almost all outer edge. Rounded outer lateral edge of MV and ‘L’-shaped inner edge. Maxillary formula: MI = 1 + 1, MII = 6–8 + 6–8, MIII = 7–8, MIV = 5–6 + 6–8, MV = 1 + 1. Mandibles (without calcareous cover) three-quarters as long as MI + plate of maxillary carrier (without free portion of carrier sclerotized plate). Calcareous cover slightly projected, fragile and crumbly, undoing easily when touched. No specimen was found with this structure complete. Description based on paratype series .

Occurrence: Intertidal: São Paulo State (near the cities of Ubatuba and Guarujá).

Etymology: The name is given in honour of Victoria Minucci Steiner, sister of Marina Minucci Steiner and niece of Tatiana M. Steiner, one of the authors of this species.

DESCRIPTION OF EXTERNAL MORPHOLOGY OF D. MARINAE AND D. VICTORIAE (HOLOTYPE DETAILS IN PARENTHESES, FIRST D. MARINAE AND THEN D. VICTORIAE )

Shape: Body rounded in cross-section in first chaetigers, flattened dorsoventrally in rest of body. Pygidium with two pairs of smooth, cirriform cirri, dorsal one with the same length as the last four to eight chaetigers and ventral half to two-thirds of dorsal length.

Colour: Fixed specimens with anterior region of body markedly beige, brown or reddish. Prostomium, antennae, cerathophores and palpophores, lips and dorsum of first ten to 14 chaetigers (holotypes 11 and 12) in larger specimens dark brown or purplish; sometimes only dark spots scattered. Small specimens without conspicuous pigmentation.

Prostomium, peristomium and appendages ( Fig. 6): Prostomium slightly rounded on anterior margin, 1.5 to twice (holotypes 1.5) as long as peristomium ( Fig. 6C). Ocellar spots absent; nuchal organ well defined, semi-oval or triangular in larger specimens ( Fig. 6A–C). Pyriform frontal lips, two-thirds as long as prostomium (holotypes two-thirds), slightly spaced between them and same spacing from palps ( Fig. 6C–E). Well-defined upper lips, distal lobe well developed with rounded end; well-defined median section, ( Fig. 6F). Lower lip in a half-moon, with welldefined median section ( Fig. 6F). Base of median antenna shifted from centre to base of prostomium, little spaced from lateral antennae. Lateral antennae and palps juxtaposed ( Fig. 6C, E). Ceratophores of antennae with same diameter, lateral slightly longer ( Fig. 6E), palpophores a little narrow, as long as median; ceratophores and palpophores about half to two-thirds of the length of prostomium (holotypes half and two-thirds). Rings usually well demarcated, median with seven to nine rings, lateral eight to ten and seven to nine palps (holotypes 8-9-8 and 7-9-7 rings); all with an additional distal ring two times longer than others, sometimes partially merged with the next. When complete, ceratostyle of median antenna reach chaetiger 13–17, lateral 7–14 and palpostyle 3–8 (holotypes 14-9-5 and 15-10-4); median generally longer than lateral. Peristomium slightly shorter than following chaetigers. Peristomial cirri smooth, pyriform, four-fiftehs to 1.5 times length of prostomium (holotypes as long as prostomium), subdistally inserted. Segments after peristomium with equivalent lengths.

Parapodia ( Fig. 7): First three to four pairs of parapodia robust, equal sizes and following a shorter bit. Cirriform dorsal cirrus 1.5 to two times longer than ventral (holotypes 1.5), more robust in first three, rarely in four to five (holotypes three and four), with following somewhat thinner, gradually decreasing to two-thirds of the length, remaining thus until near pygidial region. Cirriform ventral cirrus in first five chaetigers, the last being sometimes similar to chaetiger four in larger specimens, shorter or buttonshaped in smaller specimens; pad-like from chaetiger five to six (holotypes five). Prechaetal fold evident in MP. Acicular lobe well developed, with a projection much ( Fig. 7A–D) or little tapered in first four to five chaetigers, decreasing and becoming rounded thereafter ( Fig. 7E, F) until appearance of subacicular hook, when becomes little evident ( Fig. 7F). Cirriform postchaetal lobe in MP, with half of dorsal cirrus length, decreasing then, reaching proportion of onethird to half in posterior region. Branchiae from chaetiger five, rarely four, present in chaetigers 37–70, depending on size, being 27–57 spirals (holotypes 32 and 34) and eight to 15 single filaments (holotypes 12). Branchiae in chaetiger five more robust, with six to 13 spirals. When present in chaetiger four, branchiae are shorter than the five or six chaetiger.

Chaetae of MP ( Fig. 8): First four chaetigers with HO and one to two thin, curved capillaries ( Fig. 8F, H), sometimes chaetiger five transitional with some HO and infracicular limbates. All HO pseudocompound (except HOL), hooded, bidentate, with laterally directed teeth, being upper larger with rounded or acute/sharp end and basal shorter and tapered. HOs of chaetiger one longer than HOm and HOi ( Fig. 8A, E); HOm generally more robust than HOs ( Fig. 8A, E); sometimes both with same size ( Fig. 8E). HOi narrower and shorter than HOm ( Fig. 8E), rarely as long as this ( Fig. 8A). HOs maintain its length along all MP ( Fig. 8B–D), whereas HOm decreases length to chaetiger four to five ( Fig. 8A–D). HOi can maintain its size ( Fig. 8E–G) or it can decrease slightly until chaetiger four to five ( Fig. 8B–D). All HO with PA a little short in chaetiger four to five ( Fig. 8D, G). Hood of all hooks usually longer in chaetiger four. HOL robust, without PA, maintaining its size of one to four chaetiger. Generally, presence of one to two hooks of each type, being more frequent in HOm and HOi.

Chaetae of UP ( Figs 9, 10): Chaetiger five onward with up to 15 supracicular limbate chaetae with wide blades ( Fig. 9A). Chaetigers five to 11–21 (holotypes 18 and 15) with up to 12 short infracicular limbate chaetae with wide blades ( Fig. 9B). Subacicular bidentate hook with short hood, beginning in chaetiger ten to 21 (holotypes 13 and 18), with one to two transitional chaetigers, with limbate chaetae; first one to three chaetigers with both teeth of equal size ( Fig. 10A), then directed both laterally ( Fig. 10B–D). Pectinate chaetae little asymmetrical, from chaetiger six, nine to 17 per parapodium, less abundant in posterior region; nine to 13 teeth in anterior parapodia ( Fig. 9E, F) and ten to 16 teeth in following ( Fig. 9G). Limbate and pectinate chaetae fewer in anterior and posterior parapodia. Notopodial aciculae always fine, straight, three to 11 per parapodia. MP with four to eight neuropodial aciculae in crossed position ( Fig. 9I). All aciculae tapered distally and ventral one with smaller diameter and chaetigers five to eight to nine with aciculae in fan position, then two to six parallels ( Fig. 9J).

Tube: Inner layer parchment-like and resistant. Outer layer formed by adhering particles of sand, pieces of shells, seaweed and other objects found in environment. It has the characteristic ‘chimney’.

Remarks: The prostomium of the largest specimens is almost entirely occupied by the appendices, its length being smaller in relation to the peristomium. The projection of acicular lobe is more developed in larger animals and may be greatly reduced in smaller ones. Some variations in the HO were found, but no pattern was detected that could separate the two species. When two or more hooks of the same type occur in one parapodium, both may have the PA in an unequal position ( Fig. 8D, E). The specimens collected between 5 and 8 m deep reach smaller sizes, have a wider prostomium, less developed upper lips, slightly shorter MP and less pronounced acicular lobe.

Discussion: All characteristics described for the prostomium, peristomium, appendages, parapodia and chaetae were common to both species. The unique differences of each were detected in the morphology of the jaws. Thus, according to Table 3 and Figs 11–13, both species are characterized by the following characters. The angle of the inner callus of MI is obtuse in D. marinae ( Fig. 11) and right in D. victoriae ( Fig. 12). In general, the MII of D. victoriae is more elongate than that of D. marinae . The right MII also has some characteristic variations. Diopatra victoriae has a convex curvature at the external base, projecting backwards, absent in D. marinae . This has been verified in several specimens ( Fig. 13A, B). In the left MII of D. victoriae , the basal tooth is connected with internal base by a ridge, forming a basal callosity ( Fig. 12). Right MIV differ between both ( Fig. 13C, D): the inner arch is more pronounced in D. victoriae and internal base is narrower and curved in relation to D. marinae . In addition, a lateral compression in D. victoriae is also observed, which is not verified in D. marinae . These characteristics are also present in other specimens examined. In addition, the shape of the callus and the length of MI were also different in both species. Although other structures of jaws are shown to be different in the schemes presented herein, no differential pattern was found. Comparisons with similar species were made together with the discussion of D. hannelorae .