Namanereis canariarum, 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 canariarum sp. nov. Figs 1a, b ; 2 ; 4a-d

Namanereis hummelincki .- Hartmann-Schröder, 1988: 181-182. Non Augener, 1933. Namanereis sp. nov. 1 Glasby, Fiege & Van Damme, 2014: 28 (Table 1).

Type locality.

Canary Islands, Fuerteventura, Las Playitas (28°13'55.42"N, 13°59'4.92"W) 14 m above sea level, brackish water well.

Type material.

Holotype: TFMCBM-AN/240, coll. J. Núñez, 8-2-2002; 2 Paratypes: TFMCBM-AN/241, 2 spec., Fuerteventura, Las Playitas, Canary Islands, 28°13'56.73"N, 13°59'10.26"W, 18 m above sea level, coll. L. Santos & J.R. Docoito, 28-9-2011.

Additional material.

Fataga water mine (Barranco de Fataga, Gran Canaria, (27°47'59.18"N, 15°35'12.57"W, 160 m above sea level), 12 spec. (6 spec. TFMCBM-AN/242; 6 spec. DBAULL/2020), coll. P. Oromí & M. Naranjo, 6-12-2013.

Comparative material examined.

Material identified by G. Hartmann-Schröder (1988) as Namanereis hummelincki from Canary Islands, Fuerteventura, well S. of Betancuria, 400 m a.s.l., coll. J.H. Stock, 4-5-1987, 8 ex ZMA VPol 2953 (now in Naturalis, Leiden).

Description.

Holotype with 133 chaetigers, 46 mm long and 0.7 mm wide excluding parapodia and chaetae. Two paratypes, fragmented, one with 77 and the other with 88 chaetigers; one paratype female with gametes in the coelom.

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

Prostomium semi-circular in shape, slightly wider than long; cleft absent, shallow dorsal hollow present; two short conical frontal antennae, smooth, extending beyond tip of palpophore; palps broad and globose, biarticulated, with globular palpostyles; eyes absent (Fig. 2a ). Tentacular segment as wide as first chaetiger, but half its length, bearing three pairs of short tentacular cirri, cirrophores inconspicuous, cirrostyles smooth and tapering. The longest pair of cirrostyles extends to reach the third chaetiger (Fig. 2a ). Pharynx divided into a maxillary and an oral region, lacking paragnaths or papillae, but possessing a pair of delta-shaped jaws, dark, with only bifid terminal teeth (Figs 2a, b , 4a ).

Parapodia with notopodial branch reduced to the inner acicula; neuropodium well-developed, acicular neuropodial ligule subconical (Fig. 2c, d ) with prominent acicular lobes (Fig. 4b ). Dorsal cirri acuminated, similar in length throughout the body and clearly surpassing the parapodial lobe; ventral cirri short and thin, being about a third of the length of the dorsal cirri (Fig. 2c, d ). Notochaetae absent, neurochaetae arrangement as in Type A ( Glasby 1999), although with slight modifications. Overall, less than 7 chaetae on each parapodium; supraneuroacicular chaetae normally includes 1 sesquigomph spiniger chaeta in the postacicular fascicle (Fig. 2h, i ) and 1 heterogomph falciger chaeta in the preacicular fascicle throughout the whole body (Fig. 2e, k ). Subneuroacicular chaetae normally includes 1 heterogomph pseudospiniger chaeta (Figs 2g, j ; 4c ) and 2-3 falciger chaetae in the preacicular fascicles (Figs 2f, l , 4d ); less frequently 2 pseudospiniger chaetae, and exceptionally up to 3 falciger and no pseudospiniger chaetae might be found. In the posterior region, starting from chaetiger 60, pseudospiniger chaetae are generally longer, resembling spiniger chaetae. Supraneuroacicular falciger chaetae in chaetiger 10 with blades 4.90 × longer than width of shaft head (4.7-5.0), finely serrated, about 30 teeth, length of the teeth decreasing towards the apex. Subneuroacicular falciger chaetae in chaetiger 10 with blades 5.5 × longer than width of shaft head (5.2-5.7), finely serrated (similar to supraneuroacicular falcigers), length of the teeth decreasing towards the apex. Supraneuroacicular sesquigomph spiniger chaetae in chaetiger 10 with boss (vertical length of blade joint opposite collar) of the joint about 1.6 × length of collar. Aciculae dark honey coloured. Pygidium with terminal anus, and two short ventrolateral anal cirri, slender and smooth.

Remarks.

Morphologically, Namanereis canariarum sp. nov. belongs to the bifid-jaw group of Namanereis : this includes N. araps Glasby, 1997 (Arabian Peninsula), N. cavernicola ( Solís-Weiss & Espinasa 1991) (Mexico, Caribbean side), N. christopheri Conde-Vela 2017 (Saint Vincent, Caribbean), N. hummelincki (Augener 1933) (Caribbean), N. minuta Glasby, 1999 (Caribbean), N. llanetensis sp. nov. (Canary Islands), N. serratis Glasby, 1999 (Caribbean), N. socotrensis Glasby, Fiege & Van Damme, 2014 (Socotra Archipelago) and N. stocki Glasby, 1999 (Caribbean). The new species can be distinguished from N. cavernicola , N. minuta and N. stocki by the number and size of teeth on the blades of the supraneuroacicular falciger chaetae. Namanereis canariarum has 20-30 moderate-sized teeth, compared to 35-80 very fine teeth in N. cavernicola , 50-60 fine teeth in N. minuta , and 9-14 moderate-sized teeth in N. stocki . Furthermore, N. canariarum has much shorter antennae and tentacular cirri than the three aforementioned species. On the other hand, N. minuta and N. stocki differ from N. canariarum in having four pairs of tentacular cirri. Namanereis canariarum has shorter tentacular cirri and smooth antennae, unlike N. araps that has faintly jointed and longer tentacular cirri, with the posterodorsal one extending back to chaetiger 5; antennae in N. araps slightly exceed the length of the prostomium. Namanereis canariarum is most similar to N. hummelincki , N. christopheri , and N. llanetensis sp. nov. However, N. canariarum differs from (1) N. llanetensis sp. nov. in the longer tentacular and parapodial dorsal cirri, as well as the absence of pseudospiniger chaetae; (2) from N. christopheri in the absence of long pseudospiniger chaetae, as well as the presence of shorter and most uniform spinulation in the falciger chaetae, with a longer blade with a greater number of denticles than in N. canariarum ; (3) and from N. hummelincki by the shape of the jaws, in N. canariarum they are delta-shaped in the toothless area, and N. hummelincki is oblong in shape; as well as the greater number of pseudospiniger chaetae per parapodium in N. hummelincki . Finally, N. canariarum differs from N. serratis and N. socotrensis because these two species only have heterogomph falcigers setae in subneuroacicular fascicle.

Habitat.

The type material was collected from a brackish water well at 14 metres above sea level and about 400 metres from the coastline, located on the south of Fuerteventura. Additional material comes from the southern sector of Gran Canaria, collected in a water mine about 140 m a.s.l.. The mine had waterlogged sections rich in plant roots and slime. The stygobiont amphipod Pseudoniphargus fontinalis and the diving beetle Bidessus minutissimus (Naranjo & Martín 2016) were also found in this locality.

Distribution.

Type locality: Canary Islands, Fuerteventura, Las Playitas. Other specimens from Fataga water mine, Barranco de Fataga, Gran Canaria.

Etymology.

The species name derives from the Canary archipelago, in plural for being found in two islands.

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 2. Namanereis canariarum sp. nov. a anterior end, everted pharynx, dorsal view b jaw pieces of the pharynx, frontal view c parapodium from chaetiger 10 d parapodium from chaetiger 60 e supraneuroacicular falciger, chaetiger 30 f subneuroacicular falciger, chaetiger 10 g subneuroacicular pseudospiniger, chaetiger 30 h supraneuroacicular spiniger, blade not fully shown, chaetiger 10 i supraneuroacicular spiniger, blade fully shown, chaetiger 10 j subneuroacicular pseudospiniger, chaetiger 10 k supraneuroacicular falciger, chaetiger 30 l subneuroacicular falciger, chaetiger 30.

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.