Meiodorvillea jumarsi sp. nov.

(Figs 18–22, Table 1)

urn:lsid:zoobank.org:act: E66DB9EC-5888-4CE7-B7E1-ACC24E06D779

Type locality. Southwest Atlantic Ocean, 19˚41’29.14"S 39˚31’18.18"W, off Espírito Santo State, Brazil, 53 m depth.

Type material examined. Holotype: State of Espírito Santo – ZUEC-POL 21420 19˚ 41’29.14"S 39˚31’18.18"W (ES), 53 m, sand, 14 Jul 2011 . Paratypes: State of Espírito Santo: ZUEC-POL 21421 (1 spec) 19˚41’33.92"S 39˚31’17.74"W, 54 m, sand, 12 Dec 2010; ZUEC-POL 21422 (1 spec) 19˚47’22.52"S 39˚43’20.72"W, 41 m, sand, 15 Jul 2011; ZUEC-POL 21423 (1 spec) 19˚52’29.66"S 39˚49’8.1"W, 46 m, sand, 16 Jul 2011; ZUEC-POL 21424 (1 spec) 19˚ 37’41.83"S 39˚35’31.52"W, 41 m, sand, 15 Jul 2011; ZUEC-POL 21425 (1 spec) 19˚41’29.14"S 39˚31’18.18"W, 53 m, sand, 14 Jul 2011 . (m = meters depth).

Other material examined. State of Espírito Santo – ZUEC-POL 21426 (1 spec) 20˚1’2.6"S 39˚50’18.72"W, 51 m, sand with rhodoliths, 17 Jul 2011. State of Rio de Janeiro – ZUEC-POL 21427 (1 spec) 22˚59’0.677"S 40˚48’28.837"W, 376.6 m, 31 Jan 2009; ZUEC-POL 21428 (2 spec) 22˚59’1.044"S 40˚48’27.955"W, 380.6 m, 31 Jan 2009; ZUEC-POL 21429 (1 spec) 23˚ 10’23.820"S 40˚56’45.497"W, 432 m, 01 Feb 2009. (m = meters depth).

SEM material. State of Espírito Santo – ZUEC-POL 21430 (3 spec): 19˚41’29.14"S 39˚ 31’18.18"W, 53 m, sand, 14 Jul 2011; 20˚1’2.6"S 39˚50’18.72"W, 51 m, sand with rhodoliths, 17 Jul 2011; 19˚49’36.9"S 39˚35’42.69"W, 378 m, mud, 28 Jun 2013 (m = meters depth).

Diagnosis. One pair of antennae and one pair of palps. Dorsal cirrus papilliform from chaetigers 2 to 5–9. Ventral cirrus papilliform, absent in the first chaetiger. Chaetae capillary, geniculate on chaetigers 1 to 7–13, replaced by furcate asymmetrical towards the end of body, dorsalmost compound spiniger or falciger and Y-shaped shafts in the first chaetigers, median and ventralmost falcigers, and cultriform in last chaetigers in some specimens, replacing the ventralmost compound. Two pairs of pygidial cirri.

Description of the holotype. Complete specimen, 39 chaetigers, 2.26 mm long, 0.84 mm wide in anterior region, excluding parapodia; body width uniform, anterior region slightly wider (Fig 18A). Color in ethanol pale yellow.

Prostomium pear-shaped, as long as wide, anterior half depressed and posterior half stout globular (Figs 18B, 19A and 19B); ciliary band between both (Fig 19A). Eyes absent. One pair of clavate antennae inserted dorsolaterally on middle posterior half of prostomium, 2/3 of prostomium length (Figs 18B, 19A and 19B). One pair of small and clavate palps inserted laterally at prostomium base, half as long as antennae (Figs 18B, 19A and 19B).

Two peristomial rings, both as long as the prostomium when not retracted, posterior wider and slightly longer than anterior dorsally (Figs 18B, 19A and 19B). Transversal ciliary bands at base of peristomium and anterior chaetigers (Fig 19A).

Cylindrical parapodia (Figs 18C and 20), gradually tapering posteriorly. Papilliform dorsal cirrus on chaetigers 2 to 5, inserted almost distally on parapodium (Figs 18C, 20A and 20B), absent thereafter. Papilliform ventral cirrus in all parapodia, absent in the first one, inserted medially in the parapodium (Fig 20C and 20D), shorter than dorsal when both present.

Supra-acicular chaetae: (1) one long and serrated capillary (Fig 21E); (2) one geniculate with serrated margin present in chaetigers 1 to 8 (Figs 18C, 21A and 21F), replaced by (3) one furcate with short and asymmetrical prongs in shape and size and serrated base (Fig 21B and 21G). Sub-acicular chaetae: (4) three compound heterogomphs (Fig 21C and 21H), dorsalmost longest with falcigerous or spinigerous blade and Y-shaped shaft (Fig 20B) in the first eight chaetigers, median falcigerous, ventralmost falcigerous and shortest; distal end of shafts serrated, blades unidentate and serrated cutting edge; (5) one cultriform with serrated margin replacing the ventralmost compound in last chaetigers (Fig 21D). All chaetae gradually slender and longer along body. One internal thick acicula (Fig 20B and 20D).

Pygidium rounded and narrower than previous chaetigers. Two pairs of clavate pygidial cirri, dorsal pair twice as long as pygidium, ventral pair 1.5 times as long as pygidium (Figs 18D, 19C and 19D).

Jaw apparatus from additional non-type material with ventral and medially fused mandibles, anterior region enlarged with smooth margins without free or fused teeth, posterior region slender and curved (Fig 22A). Basal plates of maxillae with smooth inner margin, two subsymmetrical rows with 10–12 pairs of free rectangular and denticulate maxillary plates, each one with one posterior main fang and usually four anterior teeth, last and anteriormost plates larger and rounded, with small and more numerous teeth. (Fig 22A and 22B).

Variation. Complete specimens 2.26–4.75 mm long, maximum width 0.22 mm, 36–59 chaetigers. Some specimens with posterior peristomial ring covering the anterior dorsally. Dorsal cirri from chaetiger 2 to 5–9 and geniculate chaeta in chaetigers 1 to 7–13.

Remarks. Meiodorvillea jumarsi sp. nov. differs from M. apalpata in having furcate and dorsal papilliform cirrus in anterior parapodia. The latter character also occurs in M. minuta, differing from the new species in lacking geniculate chaetae. Meiodorvillea jumarsi sp. nov. has geniculate chaetae in anterior parapodia replaced by furcate, while M. penhae has furcate replaced by geniculate chaetae in median and posterior regions. Meiodorvillea jumarsi sp. nov. also differs from M. hartmanae in having dorsal cirrus papilliform in anterior parapodia and from Meiodorvillea sp. B [19] in having palps.

Geographic distribution and bathymetric range. Southwestern Atlantic Ocean, States of Espírito Santo and Rio de Janeiro (Brazil), 41–432 m; mud, sand, sandy mud, muddy sand, sand with rhodoliths.

Etymology. The specific epithet “ jumarsi ” honors Peter A. Jumars for his insight contributions to the study of polychaetes and for first describing the genus Meiodorvillea .

A key to species of Meiodorvillea is presented below, as well as the Table 1 provides an overview of the main morphological features.