Namanereis llanetensis, Núñez 1 & Glasby 2 & Naranjo 3, 2020

Nunez 1, Jorge, Glasby 2, Christopher J. & Naranjo 3, Manuel, 2020, Groundwater annelids from Gran Canaria and Fuerteventura (Canary Islands), with the description of two new species of Namanereis (Namanereidinae, Nereididae, Polychaeta), Subterranean Biology 36, pp. 35-49 : 35

Namanereis llanetensis sp. nov. Figs 1a, c , 3 , 4e, f

Namanereis sp. nov. 2 Glasby, Fiege & Van Damme, 2014: 28 (Table 1).

Type locality.

Canary Islands, Gran Canaria, Los Llanetes water mine (Valsequillo) (27°59'12.63"N, 15°28'52.03"W) 415 m above sea level.

Type material.

Holotype: TFMCBM-AN/243, coll. M. Naranjo, 8-6-2010. Paratypes: TFMCBM-AN/244, 1 spec., coll. M. Naranjo, 28-7-2010; TFMCBM-AN/245, 1 spec., coll. M. Naranjo, 12-8-2010; Los Llanetes water mine (Valsequillo, Gran Canaria), 1 spec., coll. M. Naranjo, 28-7-2010; 1 spec., coll. C. González, 12-8-2010.

Description.

Holotype with 86 chaetigers, 34 mm long and 1.3 mm wide excluding parapodia and chaetae. Paratypes with 83-88 chaetigers, 28-35 mm long and 0.8-1.0 mm wide; one paratype female with gametes in coelom (Fig. 1c ).

Living individuals with depigmented epidermis, highlighting the red dorsal blood vessel over the fleshy pink coloured body. Body uniform in width in anterior and middle region, tapering abruptly only in far posterior region; trunk convex dorsally and flattened ventrally (Fig. 1c ).

Prostomium hexagonal, two times wider than long, without a cleft but with a shallow dorsal hollow; two conical frontal antennae, smooth, extending beyond the tip of palpostyle; palps broad and globose, biarticulated, with globular palpostyles; eyes absent (Fig. 3a ). Tentacular segment as wide as first chaetiger, but slightly shorter in length. Three pairs of short tentacular cirri with indistinct cirrophores, and smooth tapering cirrostyles, the longest posterodorsal pair extending posteriorly to chaetiger 1-2 (Fig. 3a ). Pharynx without paragnaths or papillae, but with a pair of brown, delta-shaped jaws, bearing bifid terminal teeth (Fig. 3b, c ).

Parapodia with notopodial branch reduced to the inner acicula; neuropodium well-developed, acicular neuropodial ligule subconical (Fig. 3e, f ). Dorsal cirri similar in length throughout the trunk, not surpassing the parapodial lobe; ventral cirri short, only about half as dorsal cirri in length (Fig. 3e, f ). Notochaetae absent, neurochaetae as in Type A ( Glasby 1999), with slight arrangement modifications; 7 chaetae in each parapodium. Supraneuroacicular chaetae normally include 2 sesquigomph spiniger chaetae in postacicular fascicles (Fig. 3k, n ) and 1 heterogomph falciger chaeta in preacicular fascicles (Fig. 3g, i ), less frequently 1 sesquigomph spiniger chaeta and exceptionally up to 3 and no heterogomph falciger chaetae; subneuroacicular chaetae normally include 2 heterogomph spiniger chaetae in postacicular fascicles (Fig. 3l, m ) with long basal spinulation (Fig. 4e ), and 2-3 heterogomph falciger chaetae in preacicular fascicles (Figs 3h, j , 4f ), less frequently 1 heterogomph spiniger chaeta or none; exceptionally in anterior parapodia 4 heterogomph falciger and no spiniger chaetae; 1 heterogomph pseudospiniger chaeta and 3 heterogomph falciger chaetae were observed on a single anterior parapodium. No blade length gradation was observed in heterogomph falciger chaetae. Supraneuroacicular falciger chaetae in chaetiger 10 with blades 3.8 × longer than width of shaft head (3.6-4.0), with 18 finely serrated teeth (15-22), length of the teeth decreasing towards the apex. Subneuroacicular falciger chaetae in chaetiger 10 with blades 4.3 × longer than width of shaft head (4.1-4.5), and 16 (15-20), length of the teeth decreasing towards the apex. Supraneuroacicular sesquigomph spiniger chaetae in chaetiger 10 with boss (vertical length of blade joint opposite collar) about 3.0 times length of collar. Aciculae dark honey coloured. Pygidium with terminal anus and two short ventrolateral anal cirri, slender and smooth (Fig. 3d ).

Remarks.

Namanereis llanetensis sp. nov. also belongs to the so-called bifid-jaw group of groundwater Namanereis , bearing only a single pair of terminal teeth in the jaws ( Glasby et al. 2014). Namanereis llanetensis can be distinguished from all the above described species except N. serratis by the absence of long-bladed falcigers (= pseudospiniger chaetae) in the subacicular neuropodia; although, as reported above it can exceptionally occur in some anterior parapodia. The new species can be distinguished from N. serratis due to the greater number of teeth (and finer teeth) on the blades of the supraneuroacicular falcigers (only 6-11 coarse teeth in N. serratis ).

Habitat. - Type material from a freshwater mine extending into an aquifer at 415 metres above sea level, located on the eastern sector of the island of Gran Canaria. Individuals were collected in the flooded sections of the mine, with abundant plant roots, were the stygobiont amphipod Pseudoniphargus pedunculatus was also found ( Naranjo et al. 2014).

Distribution.

Type locality: Canary Islands, Gran Canaria, Valsequillo, Los Llanetes water mine.

Etymology.

The species is name after the type locality "Llanetes water mine".

Figures

Figure 1. a Distribution in Canary Islands of Namanereis canariarum sp. nov. (yellow dot) and Namanereis llanetensis (red dot) b Namanereis canariarum sp. nov. live specimen, dorsal view c Namanereis llanetensis sp. nov. live specimen, dorsal view d Los Llanetes water mine (Valsequillo, Gran Canaria) type locality of N. llanetensis sp. nov.

Figure 3. Namanereis llanetensis sp. nov. a anterior end, dorsal view b everted pharynx with jaws, dorsal view c jaws ventral view d posterior end, dorsal view e parapodium from chaetiger 3 f parapodium from chaetiger 60 g supraneuroacicular falciger, chaetiger 60 h subneuroacicular falciger, chaetiger 3 i supraneuroacicular falciger, chaetiger 3 j subneuroacicular falciger, chaetiger 3 k supraneuroacicular spiniger, blade not fully shown, chaetiger 3 l subneuropodial spiniger, blade not fully shown, chaetiger 10 m subneuroacicular spiniger, blade fully shown, chaetiger 60 n supraneuroacicular spiniger, blade fully shown, chaetiger 60.

Figure 4. Namanereis canariarum sp. nov. a jaw pieces of the pharynx, ventral view b parapodium, detail of the acicular lobes c pseudospiniger blade tip d subneuroacicular heterogomph falciger, chaetiger 60. Namanereis llanetensis sp. nov. e Holotype, detail of the basal spinulation, hererogomph spiniger, chaetiger 10 f Holotype, detail of spinulation, subneuroacicular heterogomph falciger, chaetiger 10.