Prionospio hartmanae, Peixoto & Paiva, 2020

Peixoto, Antônio João Malafaia & Paiva, Paulo Cesar, 2020, New apinnate Prionospio (Annelida: Spionidae) species from southeastern Brazil, Zootaxa 4853 (4), pp. 451-508 : 470-475

Prionospio hartmanae sp. nov.

( Figures 11–13 )

Prionospio cirrifera: Pardo et al. (2006) . Not Wirén, 1883.

Prionospio multibranchiata: Pardo & Peixoto (in press). Not Berkeley, 1927.

Type material. Brazil. Espírito Santo Basin. Holotype: Amb 7 F2, 18º 52’ 32.61” S, 39º 8’ 42.82” W, 02 Dec 2011 to 02 Feb 2012, 34m, MNRJP-2754. Paratypes: Amb1 Foz7, 19º 49’ 54.12” S, 39º 52’ 11.79” W, 11 Dec 2010 to 19 Dec 2010, 29m, MNRJP-2755 (4 ind); Amb2 Foz11, 19º 57’ 30.39” S, 39º 53’ 35.28” W, 12 Jul 2011 to 18 Jul 2011, 46m, MNRJP-2756 (3 ind); Amb7 F2, 18º 52’ 32.61” S, 39º 8’ 42.82” W, 02 Dec 2011 to 02 Feb 2012, 34m, MNRJP-2757 (3 ind) .

Additional material examined. Amb1 Foz7, 19º 49’ 54.12” S, 39º 52’ 11.79” W, 29m (5 ind); Amb1 Foz11, 19º 57’ 34.65” S, 39º 53’ 26.1” W, 43m (2ind); Amb1 Foz14, 19º 42’ 32.21” S, 39º 38’ 57.36” W, 35m (2 ind); Amb1 Foz16, 20º 1’ 3.73” S, 39º 50’ 13.76” W, 48m (2 ind); Amb2 Foz7, 19º 49’ 50.65” S, 39º 52’ 22.92” W, 28m (4 ind); Amb2 Foz8, 19º 44’ 40.28” S, 39º 46’ 32.55” W, 29m (2 ind);Amb2 Foz11, 19º 57’ 30.39” S, 39º 53’ 35.28” W, 46m (3 ind); Amb2 Foz14, 19º 42’ 28.53” S, 39º 39’ 4.25” W, 36m (2 ind); Amb2 Foz15, 19º 37’ 41.83” S, 39º 35’ 31.52” W, 35m (1 ind); Amb2 Foz17, 19º 55’ 43.7” S, 39º 45’ 39.68” W, 43m (1 ind); Amb2 Foz18, 19º 50’ 16.34” S, 39º 40’ 10.8” W, 46m (1 ind); Amb7 A2, 21º 3’ 26.62” S, 40º 23’ 0.67” W, 36 m (2 ind); Amb7 B3, 20º 34’ 53.69” S, 40º 6’ 27.35” W, 45m (3 ind); Amb7 C2, 20º 11’ 25.35” S, 40º 2’ 16.02” W, 35m (4 ind); Amb7 F2, 18º 52’ 32.61” S, 39º 8’ 42.82” W, 34m (7 ind); Amb7 F3, 18º 53’ 29.72” S, 39º 6’ 23.3” W, 43m (4 ind); Amb14 B3, 20º 34’ 53.05” S, 40º 6’ 27.68” W, 43m (2 ind); Amb14 F2, 18º 52’ 32.42” S, 39º 8’ 41.41” W, 33m (1 ind).

Diagnostic features: Up to 11 pairs of cirriform branchiae, lack of prostomial peaks and dorsal crests, sabre chaetae from chaetigers 13–14 and ventrally pointed postchaetal neuropodial lamella on chaetiger 2.

Description. A small-sized Prionospio , largest complete specimen 6.5 mm long, 0.3 mm wide at the widest part for 57 chaetigers; holotype complete, 6 mm long, 0.3 mm wide at the widest part for 50 chaetigers. Body widest and cylindrical in the branchial region, slightly dorsoventrally flattened afterwards, tapering towards the pygidium. Body color whitish in alcohol ( Fig. 11 ).

Prostomium narrow, rounded anteriorly, extending posteriorly as a narrow keel reaching the anterior margin of chaetiger 2, flanked by conspicuous nuchal organs extending up to the posterior margin of chaetiger 1 ( Figs 11 ; 12 A–B). Prostomial peaks absent. Presence of one of two pairs (in trapezoidal arrangement) of small eyes usually present or eyes absent. Peristomium surrounding prostomium and partially fused to the first chaetiger, reduced lateral wings present. Palps lost in all specimens.

Chaetiger 1 with only a few chaetae in both rami, shorter than chaetae on succeeding chaetigers. Postchaetal lamellae rounded with a pointed tip on the notopodium and digitiform on the neuropodium ( Figs 12B ; 13A ). Prechaetal lamellae absent.

Notopodial postchaetal lamellae foliaceous in chaetigers 2–13 ( Fig. 13 B–D), rounded from chaetiger 14 and gradually reduced in size towards posterior region, present as a low flap in posterior region, slightly more developed and triangular on last 3–8 chaetigers. Notopodial prechaetal lamellae absent throughout. Dorsal crests absent ( Fig. 12A ).

Neuropodial postchaetal lamellae triangular with pronounced ventrally pointed tip in chaetiger 2 ( Fig. 13B ). Lamellae subtriangular on chaetiger 3 ( Fig. 13C ), elliptical on chaetigers 4–8 ( Fig. 13D ), rounded on chaetigers 9–20, and present as a low flap on posterior chaetigers. Neuropodial prechaetal lamellae absent throughout.

Chaetae from notopodia and neuropodia organized in two rows of narrowly unilimbated capillaries, bearing light granulations along shaft ( Fig. 13E ). Chaetae from both rows of almost equal length, with neuropodial chaetae slightly shorter than notopodial chaetae. Towards posterior region, capillaries become progressively elongate, nonlimbate, non-granulate, thinner and less numerous ( Fig. 13F ).

Hooks in notopodia from chaetigers 23–41, up to four per fascicle, accompanied by 1–4 short non-limbate capillaries ( Fig. 13G ). Hooks in neuropodia starting from chaetigers 17–22, up to five per fascicle, accompanied by 1–4 short non-limbate capillaries. All hooks multidentate, with 10 secondary teeth organized in two rows above main tooth ( Figs 12D ; 13H ). Small secondary hood present ( Fig. 13H ). Sabre chaetae starting from chaetigers 13–14 (usually chaetiger 13). Sabre chaetae non-limbate, with granulations along upper part of shaft ( Fig. 13I ).

Up to 11 pairs of smooth and cirriform branchiae, tapered at tips. Branchiae starting from chaetiger 2, up to three times longer than notopodial lamellae, slightly reduced in length towards last branchial pair. Branchiae densely ciliated throughout length (except tip), completely free from notopodial postchaetal lamellae ( Figs 12 A–C; 13J).

Pygidium bearing one dorsal cirrus and two short ventro-lateral cirri ( Fig. 13K ).

Oocytes from chaetiger 15, measuring up to 90 µm.

Methyl green pattern: Prostomium, dorsal side of the peristomium and margins of lamellae up to chaetiger 20 intensely stained. Stain diffused on the ventral side up to chaetiger 15.

Remarks. Prionospio hartmanae sp. nov. shares similarities with P. fosterae sp. nov., P. perkinsi and P. lighti in having a rounded prostomium, similar branchial number and morphology (up to 11 pairs in P. hartmanae sp. nov., up to 10 pairs in P. perkinsi and up to 12 pairs in P. lighti , apinnate and cirriform in all species), and lack of dorsal crests. The species can be separated based on the lack of prostomial peaks in P. hartmanae sp. nov. (present in P. lighti and P. perkinsi ), presence of sabre chaetae (absent in P. fosterae and P. perkinsi ), number of secondary teeth on the hooded hooks (five pairs in P. hartmanae sp. nov., one pair in P. fosterae sp. nov., three pairs in P. lighti and two pairs in P. perkinsi ) and morphology of the postchaetal lamellae from chaetiger 1 (rounded with a pointed tip on the notopodium and digitiform on the neuropodium in P. hartmanae sp. nov., digitiform on the notopodium and rounded on the neuropodium in P. fosterae sp. nov., rounded on the notopodium and digitiform on the neuropodium in P. perkinsi and absent on the notopodium and digitiform on the neuropodium in P. lighti ) ( Maciolek, 1985).

Prionospio hartmanae sp. nov. is most similar to P. multibranchiata , a species originally described from British Columbia, Canada, in the eastern Pacific Ocean, and regarded as cosmopolitan, including doubtful records in Brazil (São Paulo State) ( Amaral et al. 2013). Despite being considered cosmopolitan, it is currently known that P. multibranchiata records outside its type-locality likely represents new species (see Dagli & Çinar 2011 and Delgado-Blas et al. 2019).

Prionospio multibranchiata was redescribed by Mackie (1984), based on material from Scotland, England and Sweden, by Maciolek (1985), based on material from Mexico, Florida ( USA) and Washington ( USA), and by Delgado-Blas et al. (2019) based on material from British Columbia ( Canada), being closest to the type-locality. According to Dagli & Çinar (2011) and Delgado-Blas et al. (2019), specimens examined by Mackie (1984) do not correspond to Prionospio multibranchiata and may represent a new species.

When compared with Maciolek’s redescription (1985), species share a similar prostomial morphology (narrow and rounded anteriorly), lack of prostomial peaks, the same branchial number and morphology (up to 11 pairs of apinnate cirriform branchiae) and a considerable overlap in the starting chaetiger of notopodial hooded hooks (chaetigers 23–41 in P. hartmanae sp. nov. and chaetigers 26–34 in P. multibranchiata ) and sabre chaetae (chaetigers 13–14 in P. hartmanae sp. nov. and chaetigers 10–16 in P. multibranchiata ). However, the aforementioned species can be separated based on the number of secondary teeth on the hooded hooks (five pairs in P. hartmanae sp. nov. and three pairs in P. multibranchiata ), shape of the postchaetal neuropodial lamellae from chaetiger 1 (digitiform in P. hartmanae sp. nov. and rounded in P. multibranchiata ), lack of dorsal crests in P. hartmanae sp. nov. (present on several postbranchial chaetigers in P. multibranchiata ) and lack of notopodial postchaetal lamellae from chaetiger 1 in P. multibranchiata (rounded with a pointed tip in P. hartmanae sp. nov.). Prionospio hartmanae sp. nov. also possess a ventrally pointed neuropodial lamellae on chaetiger 2, which is absent in P. multibranchiata .

According to Delgado-Blas et al. (2019) redescription of P. multibranchiata , species are similar in lacking prostomial peaks, lacking dorsal crests, partial overlap on the starting chaetiger on notopodial hooded hooks (chaetigers 37– 40 P. multibranchiata and chaetigers 23–41 in P. hartmanae sp. nov.) and similar pygidial morphology. However, these species differ on the prostomial shape (triangular and truncate anteriorly in P. multibranchiata and narrow and anteriorly rounded in P. hartmanae sp. nov.), branchial number (up to 10 pairs in P. multibranchiata and up to 11 pairs in P. hartmanae sp. nov.), branchiae morphology (triangular in P. multibranchiata and cirriform in P. hartmanae sp. nov.), lamellae morphology in chaetiger 1 (rounded in both rami in P. multibranchiata and rounded with a pointed tip in the notopodium and digitiform in the neuropodium of P. hartmanae sp. nov.) and morphology of neuropodial postchaetal lamellae in chaetiger 2 (square-shaped in P. multibranchiata and triangular with ventrally pointed tip in P. hartmanae sp. nov.),

Prionospio hartmanae sp. nov. can also be distinguished from P. multibranchiata based on the morphology of the remaining neuropodial postchaetal lamellae from the branchial region (rounded in P. multibranchiata and elliptical in P. hartmanae sp. nov.), lack of prechaetal lamellae in P. hartmanae sp. nov. (present in both rami in P. multibranchiata ), starting chaetiger of neuropodial hooded hooks (chaetigers 14–16 in P. multibranchiata and chaetigers 17–22 in P. hartmanae sp. nov.) and starting chaetiger of sabre chaetae (chaetigers 11–12 in P. multibranchiata and chaetigers 13–14 in P. hartmanae sp. nov.) ( Delgado-Blas et al. 2019).

The ventrally pointed postchaetal neuropodial lamella on chaetiger 2 is similar to the lamellae reported in P. cirrifera ( Mackie, 1984) and P. aluta ( Maciolek, 1985) . However, P. hartmanae sp. nov. can be readily distinguished from these species due to the lack of interparapodial pouches (present from chaetigers 4–5 to chaetigers 37–38 in P. aluta and from chaetigers 4–8 to chaetigers 9–24 in some specimens of P. cirrifera examined by Mackie, 1984), lack of dorsal crests (present from chaetigers 10–11 to almost the end of the body in P. cirrifera and present on several postbranchial chaetigers in P. aluta ) and by the branchial morphology (up to 11 pairs of apinnate and cirriform branchiae in P. hartmanae sp. nov., up to eight pairs of apinnate and cirriform branchiae in P. cirrifera and six pairs of robust subtriangular branchiae in P. aluta ).

According to Delgado-Blas & Salazar-Silva (2011), both P. cirrifera and P. aluta belong to a species-complex that includes species bearing a ventrally pointed neuropodial postchaetal lamellae on chaetiger 2, which would include P. hartmanae sp. nov.

Etymology. The specific epithet, hartmanae , is a tribute to Olga Hartman (1900–1974), an invertebrate zoologist who made invaluable contributions to the study of polychaetes.

Habitat: Gravel sand to fine sand, 28–48 m depth.

Distribution: Southeastern Brazil (Espírito Santo and Campos basins), Atlantic Ocean.

Figures

FIGURE 11. Prionospio hartmanae sp. nov., dorso-lateral view (MNRJP-2754, holotype), showing characteristic color in ethanol. Abbreviations: br, branchia; ey, eye; pe, peristomium; pr, prostomium.

FIGURE 12. SEM of Prionospio hartmanae sp. nov. A. Anterior end and mid-body chaetigers, dorsal view. B. Close-up of anterior end, dorsolateral view. C. Anterior chaetigers and mid-body, lateral view. D. Hook (hood removed). Abbreviations: br, branchia; pe, peristomium; pr, prostomium.

FIGURE 13. Prionospio hartmanae sp. nov. A. Chaetiger 1. B. Chaetiger 2. C. Chaetiger 3. D. Chaetiger 4. E. Anterior capillary chaeta. F. Posterior capillary chaetae. G. Companion capillary chaetae. H. Hooded hook. I. Sabre chaetae. J. Branchia. K. Posterior-most chaetigers and pygidium.