Questa ericnunezi, Núñez & Martínez, 2023

Núñez, Jorge & Martínez, Alejandro, 2023, Two new species and records of the genus Questa (Annelida: Orbiniidae) from Azores and Canary Islands, Central Atlantic Ocean, Zootaxa 5319 (3), pp. 403-412 : 407-410

Questa ericnunezi n. sp

Figures 3 , 4

Questa sp. Martínez et al. 2009: 173 (Table 1).

Type Material. Canary Islands, Tenerife.- Holotype (female) TFMCBM-AN/250, Punta Sama , 28º06.23’N 16º28.37’W, sandy patches amongst rocks, 6 m, 01-2006, coll. A. Martínez, Paratypes : TFMCBM-AN/251, 8 specimens; TFMCBM-NA/252, 1 female; TFMCBM-NA/254, 5 specimens. Same locality, date, and collector than the holotype.

Other material examined. Tenerife.- SEM preparation on stub, DBAULL STUB 2 , Punta Sama, 28º06.23’N 16º28.37’W, sandy patches amongst rocks, 6 m, 01-2006. Lanzarote, Túnel de la Atlántida , Montaña de Arena, 29º09.43’N 13º25.87’W, DBAULL-JAMEOS, 4 specimens and 1 male whole-mounted specimen on separate slide 21-03-2008. Coll. A. Martínez. (as Questa sp. , in Martínez et al. 2009) .

Type Material examined for comparison. Questa riseri Giere & Erséus, 1998 , ZMUH P-23421, Holotype male, ZMUH P-23438, 2 Paratypes (male and female); ZMUH P-23420, 1 Paratype male. ZMUH P-23430, paratype male; ZMUH P-23439, paratype male; ZMUH P-23427, 1 male; ZMUH P-23422, 1 paratype male.

Description. Body elongate and threadlike ( Fig. 3A ), holotype length (fixed) 6.4 mm and 38 chaetigers, width in pre-genital region about 0.22–0.32 mm, and 0.20– 0.15 mm in post-genital region. Paratypes length (fixed) about 1.0– 6.6 mm and about 36–48 chaetigers, width in pre-genital region 0.20–0.28 mm and 0.18– 0.12 mm post-genitally. Body segments cylindrical in cross section; well-marked intersegmental annulation throughout the body ( Fig. 3B, C ), anterior segments with 2–3 conspicuous annuli per segment, 7–8 subsequently ( Fig 3B, C ). Prostomium small, conical, narrow rounded tip, lacking appendages or eyes ( Fig. 3B ); nuchal organs as paired slits on posterior lateral margin ( Fig. 3B ). Peristomium as wide as the following metastomial segments, without appendages or chaetae ( Fig. 3B ); ventral mouth opening and buccal pad, visible by transparency with marked transverse muscular bands. Pre-genital region with the first five chaetigers more compressed than the following, and in the post-genital region they progressively narrow towards the pygidium ( Fig. 3B ). Paired branchiae present dorsally in posterior segments ( Figs 3A, D ; 4A ), totaling 12–18 pairs (holotype 12 pairs), non-ciliated ( Fig. 4A ), and exceptionally reaching to a maximum of 20 pairs. Parapodia biramous, composed of low mounds with noto- and neurochaetae ( Fig. 3B ). Three kinds of chaetae on anterior chaetigers, including long hair-like pinnate capillaries ( Fig. 3F ) and bidentate hooks in both rami, and notopodial furcate chaetae with median tooth in anterior-most 2–5 chaetigers ( Fig. 4B, C, E ). Furcate chaetae (fork-shaped) with two outer branches well-developed, and a pointed median tooth, less developed and shorter than lateral branches.; 1–3 chaetae in dorsal bundle ( Fig. 4B ). Bidentate hooks with geniculate shafts, well developed main tooth with subdental ligament ( Fig. 4D ) and small upper accessory tooth ( Fig. 4D, E ), 1 per bundle, rarely 2. Pygidium bilobed with a dorsoventral incision ( Fig. 3D ), bearing two pairs of well-developed dorsal and ventral cirri ( Fig. 3D ). Anal opening in terminal and dorso-ventral position ( Fig. 3D ).

Sexually dimorphic. Males with reduced chaeta on chaetigers 12–13, and a conspicuous slit-like dorsal fold in 13 ( Fig. 3A, B, C ). Females without reduced chaeta, and carrying oocytes in chaetigers 11–12.

Etymology. The species is dedicated to Eric Núñez, son of the first author.

Distribution. Endemic from the Canary Islands.

Remarks. Only four of the known species in the genus Questa have furcate chaetae in the anterior chaetigers: Q. riseri Giere & Erséus, 1998 from Bermuda, Q. media Westheide, 1981 from Galápagos, Q. trifurcata ( Hobson, 1970) from Massachussetts and Q. retrospermatica Giere, Ebbe & Erséus, 2007 from Hawai’i. Questa riseri , Q. trifurcata and Q. ericnunezi n. sp. are the three species that have similar furcate chaetae with a medium tooth; whereas Q. retrospermatica has two short, medium teeth. Questa trifurcata lacks of branchiae and caudal cirri, while Q. ericnunezi n. sp. has branchiae and two pairs of caudal cirri. Questa riseri is the species closest to Q. ericnunezi n. sp. in terms of morphological characters. The main difference between these two species is the number of branchial pairs, Q. riseri has more than 20 pairs, from 23–28 according to Giere & Erséus (1998), whereas Q. ericnunezi n. sp., has normally 12–18 pairs, and only exceptionally reaching to a maximum of 20 pairs. The intersegmental annulation of each chaetigers also differentiates both species: it is poorly marked in Q. riseri , but well-marked throughout the body in Q. ericnunezi n. sp., although this character is less important, since it depends on the fixation of the specimens.

Figures

FIGURE 3. Questa ericnunezi sp. n. SEM micrographs: A. Complete specimen, dorsal view; B. Anterior end, dorsal view; C. Dorsal fold; D. Posterior end with branchiae, dorsal view.Abbreviations: an anus, br branchia, cc capillary chaeta, ch1, chaetiger 1, df dorsal fold, no nuchal organ, nr neurochaeta, nt notochaeta, pc pygidial cirri, pe peristomium, pr prostomium.

FIGURE 4. Questa ericnunezi sp. n. SEM micrographs: A. Chaetiger with branchiae, dorso-lateral view; B. Tridentate furcate chaetae; C. Detail of two furcate chaeta; D. Hooks with subdental ligament; E. Chaetal bundle, with capillary pinnate, tridentate furcate and hook chaetae; F. Capillary pinnate chaetae. Abbreviations: at apical tooth, br branchia, lg subdental ligament, mt main tooth.