Kirkegaardia blakei, Freitas & Ribeiro & Ruta, 2022

Freitas, Roberta, Ribeiro, Rannyele Passos & Ruta, Christine, 2022, Kirkegaardia Blake, 2016 (Annelida: Cirratulidae) from Southeastern Brazil with description of nine new species, PLoS ONE (e 0265336) 2016 (5), pp. 1-27 : 7

Kirkegaardia blakei sp. nov.

urn:lsid:zoobank.org:act:9DC8FAC8-2445-4FBA-BE7B-8A0235CDE991

Fig 3

Material examined. BRAZIL: Campos Basin – Holotype – -19.69275556˚S -39.52138889˚W, 48 m, 12/12/10, ( MNRJP-002971 ); Paratypes – -19.91560000˚S -39.94467500˚W, 32 m, 16/12/ 10, one ind., ( MNRJP-002972 ); - 21.18725000˚S -40.09813889˚W, 683 m, 04/02/09, one ind., ( MNRJP-002973 ).

Diagnosis. Abdominal region with simple capillaries, gradually replaced by denticulated capillaries. Pre-pygidial abdominal region slightly expanded with 8–10 setigers, with long setae with curved tips and simple denticulated setae.

Description. Complete holotype with 55 setigers, 3 mm long, 0.1 mm wide in thoracic region, and 0.09 mm wide in abdominal region. Prostomium triangular and narrow ( Fig 3A ); Eyes absent. Peristomium large, with 3–4 narrow rings ( Fig 3A ). Dorsal tentacles on posterior margin of peristomium ( Fig 3A ). Thoracic region expanded with 7–8 setigers, thoracic dorsal groove barely visible ( Fig 3A ). First pair of branchiae inserted dorsolaterally on setiger 1 ( Fig 3A ), present up to abdominal region. Abdominal setigers narrow. Parapodia between middle abdominal and pre-pygidial segments with slightly elevated lobes ( Fig 3B ). Thoracic region with setae simple capillaries; abdominal region with 4–5 denticulated noto and neurosetae ( Fig 3B ) that gradually replace most smooth capillaries; pre-pygidial abdominal region with long setae with curved tips ( Fig 3C ) and denticulated capillaries ( Fig 3D ). Pre-pygidial region slightly expanded with 8–10 setigers ( Fig 3E ). Pygidium slightly expanded, with conical ventral lobe ( Fig 3E ).

Remarks. Kirkegaardia blakei sp. nov. has the peristomial rings with 3–4 very well-marked and concentrated rings at the end of the peristomium. According to Blake [ 22], these rings are usually smooth, and often difficult to see in optical microscopy, sometimes requiring SEM for verification. Kirkegaardia blakei sp. nov. has noto and neurosetae denticulated capillaries in the abdominal region, and unusual long setae modified with a gently curved tip, without denticles or fibrils in the pre-pygidial one. The abdominal region of K. blakei sp. nov. is similar to K. hampsoni , however K. hampsoni has only denticulated setae. For all these characteristics, the species was considered new for science.

Etymology. This species is named in honor of Dr. James Blake for his important works that contributed to the knowledge of polychaetes, including the family Cirratulidae .

Figures

Fig 3. Kirkegaardia blakei sp. nov. (A) anterior end, dorsal view; (B) posterior parapodium, anterior view; (C) notopodial seta with long curved tips; (D) neuropodial denticulated capillary; (E) posterior end, dorsal view. A–E, (MNRJP-002971). Scale bars: 100 μm (A and E); 200 μm (B–D). Type locality. Atlantic Ocean: Campos Basin (Brazil). Habitat. Sandy sediments, 38 and 683 m depth. Distribution. Presently known only from Atlantic Ocean: Campos Basin (Brazil). Methyl Green. No pattern, stain not retained. https://doi.org/10.1371/journal.pone.0265336.g003