Scyphoproctus paivai, Silva & Amaral, 2019

Silva, Camila Fernanda Da & Amaral, Antonia Cecilia Zacagnini, 2019, Scyphoproctus Gravier, 1904 (Annelida, Capitellidae): description of three new species and relocation of Heteromastides Augener, 1914 in Scyphoproctus, Zootaxa 4560 (1), pp. 95-120 : 104-107

Scyphoproctus paivai sp. nov.

( Figures 5 ̄7)

Type series. Holotype ( ZUEC POL 20591): state of São Paulo, São Sebastião, Araçá Bay (23°48'S, 45°24'W): coll. 15 Feb 2013; rocky shore; intertidal; 1 spec . Paratypes: state of São Paulo, São Sebastião, Araçá Bay (23°48'S, 45°24'W): paratypes 1 and 2 ( ZUEC POL 20571): coll. 19 Mar 2015; rocky shore; intertidal; 2 specs . Paratypes 3–11 ( ZUEC POL 20574): coll. 16 May 2014; rocky shore; intertidal; 9 specs . Paratype 12 ( ZUEC POL 20575): coll. 10 Nov 2013; rocky shore; intertidal; 1 spec . Paratype 13 ( ZUEC POL 20577): coll. 29 Oct 2011; soft-bottom; intertidal; Stn. 20(2)A; 1 spec. State of São Paulo, São Sebastião, São Francisco Beach (23°44'54"S, 45°24'34"W): paratype 14 ( ZUEC POL 20580): coll. 23 Jun 2013; sandy beach; Stn. 45; 1 spec . Paratypes 15–17 ( ZUEC POL 20581): coll. 23 Jun 2013; sandy beach; Stn. 72; 3 specs . Paratypes 18 and 19

(ZUEC POL 20582): coll. 23 Jun 2013; sandy beach; Stn. 48; 2 specs. Paratypes 20–25 (ZUEC POL 20583): coll. 11 Apr 2013; sandy beach; Stn. 20P; 6 specs. Paratype 26 (ZUEC POL 20590): coll. 0 4 Oct 1995; sandy beach; 1 spec. State of Paraíba, Cabo Branco Beach (7°08'S, 34°47'W): paratypes 27–29 (ZUEC POL 20587): coll. 0 1 Feb 2010; in rhodoliths; intertidal; 3 specs.

Additional material examined. State of São Paulo, São Sebastião, Araçá Bay (23°48'S, 45°24'W). (ZUEC POL 20572): coll. 15 Feb 2013; rocky shore; intertidal; 5 specs. (ZUEC POL 20573): coll. 26 Sep 2011; softbottom; intertidal; Stn. 4(3)A; 1 spec. (ZUEC POL 20576): coll. 23 Feb 2013; soft-bottom; intertidal; Stn. 152(1)G; 1 spec. (ZUEC POL 20578): coll. 12 Oct 2012; soft-bottom; intertidal; Stn. 3(2)Pr; 1 spec. (ZUEC POL 20579): coll. 0 8 Feb 2012; soft-bottom; intertidal; Stn. 66(2)Pr; 1 spec. State of São Paulo, São Sebastião, São Francisco Beach (23°44'54"S, 45°24'34"W). (ZUEC POL 20584): coll. 11 Apr 2013; sandy beach; intertidal; Stn. 5G; 2 specs. (ZUEC POL 20585): coll. 23 Jun 2013; sandy beach; intertidal; Stn. 43; 3 specs. State of São Paulo, Caraguatatuba, Enseada Beach (23°43'40"S, 45°25'10"W). (ZUEC POL 20586): coll. 12 Apr 2013; sandy beach; intertidal; Stn. 47P; 3 specs. State of Paraíba, Cabo Branco Beach (7°08'S, 34°47'W). (ZUEC POL 20588): coll. 0 8 Feb 2009; in rhodoliths; intertidal; 1 spec. State of Paraíba, Jacumã Beach (7°14'S, 34°47'W). (ZUEC POL 20589): coll. 29 Jan 2010; in rhodoliths; intertidal; 1 spec.

Comparative material. Scyphoproctus edmondsoni Magalhães & Bailey-Brock, 2012 , holotype USNM 1191161—Nuupia Pond, Hawai, 21°25'58.8'' N, 157°44′52.8″ W, paratypes USNM 1191162— Nuupia Pond , Hawai, 21°25'58.8'' N, 157°44'52.8'' W .

Description. Complete holotype 21 mm long, 0.9 mm wide for 83 chaetigers. Complete specimens ranged from 2.5– 15 mm, long 0.3–1.1 mm wide and 24–79 chaetigers; incomplete specimens ranged from 0.3–2.2 mm wide. Body rounded; thorax wider than abdomen; abdomen slightly narrowing toward pygidium ( Fig. 5A ). Whitish color in alcohol.

Prostomium rectangular, 2x longer than wide, rounded on anterior end ( Figs 5A ; 6B ̄C; 7A); nuchal organs not observed; eyespots as a pair of densely pigmented red areas forming inverted “U” ( Figs 5A ; 6C ). Proboscis globular-shaped, with several robust papillae ( Fig. 6C ). Peristomium longer than achaetous segment 1 ( Figs 5A ; 6B ; 7A ). Complete inter-segmental groove between peristomium and achaetous segment ( Figs 5A ; 7A ).

Thorax with 11 segments, including peristomium, one additional achaetous segment, and 9 chaetigers. Bilimbate capillaries in noto- and neuropodia of chaetigers 1–9. Thorax smooth with chaetigers 1 biannulate; shallow inter-segmental grooves between chaetigers. First chaetiger biramous. Parapodial lobes well-separated; notopodia inserted dorso-laterally and neuropodia laterally. Lateral organs present from the achaetous segment, more conspicuous on larger specimens. Transition between thorax and abdomen subtle, marked mainly by chaetal change ( Figs 5A ; 6A ; 7A ).

Abdominal chaetigers without capillaries. Abdominal notopodia and neuropodia with well-developed tori pads and well-separated, distance between tori remaining similar throughout abdomen ( Fig. 6F ). First abdominal notopodium with 9 hooks; first abdominal neuropodium with 11 hooks; number of hooks in both rami increases on next two to three chaetigers and afterwards reduces toward posterior end. Notopodial hooks (seen with SEM) with round and large main fang, right angle with shaft, surmounted by more than 20 teeth arranged in 4–5 rows (3–4 basally, intercalated among all teeth of tori ( Fig. 7C ̄D); remaining teeth smaller and with diversified arrangement); thick hood with smooth margin ( Fig. 7C ̄D). Neuropodial hooks (with SEM) with pointed and large main fang, right angle with shaft, surmounted by 15–16 teeth arranged in three rows (3–4 basally, intercalated among the teeth of the tori; 5–6 median; 6–7 apically); thin hood with fringed margin (uneven and pointed fringes) ( Fig. 7E ).

Four pre-pygidial segments with neuropodial hooks and notopodial spines (3,3,3,2, each side). Anal plaque poorly developed, “w”-shaped, with one set of protruding spines (1 spine on each side). Large anal aperture between anal cirri; two short and broadly rounded cirri without membrane ( Figs 5 B–C; 6D; 7B).

Variation. Paratypes with 11–12 segments, including the peristomium, one additional achaetous segment, and 9–10 chaetigers. Number of hooks of the first abdominal lobe size dependent, notopodium ranging from 2 to 40 and neuropodium from 5 to 43 hooks.

Methyl green staining pattern. Chaetigers 1 and 2 with two longitudinal bands of large dark speckles on anterior and posterior parts of the segments, spaced equally from each other; chaetigers 6–9 staining with small dark speckles, number of speckles increasing toward chaetiger nine; first two abdominal chaetigers staining darkly around the noto- and neuropodial tori and leaving the glandular pad unstained ( Fig. 6E ).

Remarks. Scyphoproctus paivai sp. nov. belongs to a group of species with a poorly developed anal plaque, which includes S. armatus and S. edmondsoni . Scyphoproctus armatus differs from Scyphoproctus paivai sp. nov. by the number of thoracic chaetigers, number of pre-pygidial segments with acicular spines, and shape of anal cirri. Scyphoproctus armatus has nine thoracic chaetigers and Scyphoproctus paivai sp. nov. has 9–10. The number of pre-pygidial segments with acicular spines in S. armatus is 8–11 and in Scyphoproctus paivai sp. nov. is four. Anal cirri are digitate in S. armatus and “w”-shaped in Scyphoproctus paivai sp. nov.

Scyphoproctus edmondsoni also has 9–10 thoracic chaetigers, abdominal noto- and neuropodia with wellseparated glandular tori pads, and inflated anal cirri, but it differs from Scyphoproctus paivai sp. nov. by the number of pre-pygidial segments with acicular spines (only one) and by the hooded hooks (number and arrangement of teeth and shape and thickness of the hood). Hooded hooks in Scyphoproctus paivai sp. nov. are different between noto- and neuropodia. Notopodial hooks have more than 20 teeth arranged in 4–5 rows and thick hoods with smooth margins; neuropodial hooks have 15–16 teeth arranged in three rows and thin hoods with a fringed margin (uneven and pointed fringes). On the other hand, hooded hooks of S. edmondsoni are similar between noto- and neuropodia, with several teeth arranged in 3–4 rows, and with a thick and smooth hood.

Etymology. This species is named after the Prof. Paulo de Cesar Paiva from the Universidade Federal do Rio de Janeiro, an expert in benthic ecology, marine phylogeography, and polychaete systematics; an exceptional teacher; and specially a great friend.

Habitat. From intertidal to shallow subtidal regions (0–0,5m), in soft-bottom, rhodoliths and rocky shore.

Type locality. Araçá Bay , São Paulo, Brazil, 23°48'S, 45°24'W (South Atlantic Ocean) .

Distribution. South Atlantic Ocean: Brazil (states of Paraíba and São Paulo).

Figures

FIGURE 5. Scyphoproctus paivai sp. nov. (A) Anterior end, lateral view; (B) Posterior end, ventral view; (C) Posterior end, dorsal view. Scale bars: A, 1 mm; B, C, 0.5 mm.

FIGURE 6. Scyphoproctus paivai sp. nov. (A) Complete specimen, lateral view; (B) Anterior end, lateral view; (C) Anterior end, lateral view; (D) Posterior end; ventral view; (E) Incomplete specimen, methyl green staining pattern; (F) Abdominal region, ventral view. Scale bars: A, 1 mm; B, 0.5 mm; C, D, E, F, 0.2 mm.

FIGURE 7. Scyphoproctus paivai sp. nov., SEM. (A) Anterior end, lateral view; (B) Posterior end, ventral view; (C) Notopodial hooded hooks, frontal view; (D) Notopodial hooded hook, lateral view; (E) Neuropodial hooded hooks, frontal view. Scale bars: A, 0.5 mm; B, 0.2 mm; C, E, 5 µm; D, 2 µm.