Allocyclops nudus, Fiers, Frank & Lagnika, Moissou, 2015

Fiers, Frank & Lagnika, Moissou, 2015, Four new representatives of the genus Allocyclops Kiefer, 1932 from semi-consolidated subsoil aquifers in Benin (Copepoda, Cyclopoida, Cyclopidae), Subterranean Biology 16, pp. 1-36 : 12-13

Taxon classification Animalia Cyclopoida Cyclopidae

Allocyclops nudus sp. n. Figs 4E, F, J, 5G, H, 10, 11, 12

Syn. Allocyclops n sp. [partim] in Lagnika et al. 2014b

Type locality.

Ladjifarani or "Nouveau quartier", Parakou District, Ouémé drainage basin: Well B6 (details in Table 2).

Type material.

Holotype female, dissected and mounted on 2 slides, RBINSc COP 10.334A-B, allotype male, dissected and mounted on 2 slides, RBINSc COP 10.335A-B; paratypes: dissected female RBINSc 10.367A-B, preserved material: 7 females, 3 males, 5 juveniles (RBINSc COP 10.333) all collected 29/10/2011; additional paratypic material (topotypes): 3 females collected 16/01/11 (preserved RBINSc COP 10.352).

Etymology.

From the Latin adjective “nudus” meaning naked and refers to the absence of hairy or spinular ornamentation on the pedigers surface and caudal rami, contrasting the species from Allocyclops spinifer sp. n. and Allocyclops pilosa sp. n.

Additional material.

(1) Parakou District, Ouémé drainage basin.

- Well A1: 27/08/2011: 1 ♀, 8 ♂♂ (preserved material RBINSc COP 10.337); 11/01/2011: 4 ♀♀, 1 ♂, 40 juveniles, decomposed condition (preserved material RBINSc COP 10.348); 15/02/2011: 2 ♀♀, 3 ♂♂, 20 juveniles (preserved material RBINSc COP 10.351); 10/07/2012: 48 ♀♀, 12 ♂♂ (preserved material RBINSc COP 10.338);

- Well A5: 16/11/2010: 2♂♂, 4 juveniles (preserved material RBINSc COP 10.350);

- Well C3: 30/10/2011: 1 ♂ (dissected male RBINSc COP 10.368); 14/02/2011: 27 ♀♀, 1 ♂ (preserved material RBINSc COP 10.349).

Description.

Female: Body (Fig. 10A) typically cyclopid with prosome longer than urosome (ratio: 1/0.8). Principal body flexure well marked, rather wide. Genital double-somite widest in anterior third, tapering caudally, and as long as widest part. Anal somite with crescent operculum, not expanded. Anal sinus unadorned. Length 900 μm (holotype, paratypes 890-962 μm, n=5). Posterodorsal margins of cephalothorax and pedigers 2-3 straight, of pediger 4 slightly irregular. Urosomite 1 with straight posterodorsal fringe. Posterior margin of genital double-somite and urosomites 4-5 wide, coarsely serrate. Posterior margin od anal somite with uninterrupted row of spinules along ventral and dorsal margins.

Caudal rami cylindrical with triangular depression along anterior half of medial margin, less than 3 times longer than wide (L/W-ratio 1/2.7-2.8). Anterolateral seta, pinnate, short, without spinules near articulation. Posterolateral element shorter than ramus in holotype (ratio: 0.9/1) ranging from 0.8/1-1.0/1 in paratypes), with long and slender spinules along outer side of the stem, pinnate along the inner side. Spinules present at it insertion with ramus. Medial element longer than ramus (ratio: 1.15-1.25/1) and pinnate. Principal terminal setae with breaking plane and pinnate. Dorsal seta 1.3-1.4 times longer than ramus, and articulating on small basal part. Integument of rami unadorned.

Antennule 11-segmented with typical armament, not reaching to posterolateral edge of cephalothorax. Segment 1 with set of slender spinules and set of short ones (Fig. 4 F). Aesthetasc on segment 8 linguiform, reaching beyond middle of segment 9. Aesthetasc on segment 10 filiform, shorter than accompanying seta and reaching halfway terminal segment. Aesthetasc on segment 11 tubular, as long as segments 9-11 combined, and shorter than accompanying seta (Fig. 4E).

Antenna with general appearance and armature as in Allocyclops chappuisi (see Fiers 2012). Frontal surface of coxobasis with a cluster of 7-9 small spinules near middle of outer margin and a row of slender spinules in proximal half near abexopodal margin (Fig. 5G). Caudal surface of coxobasis with 3 sets of narrow spinules in proximal half: 2 near outer margin, 1 near abexopodal margin (Fig. 5H).

Mouthparts as in preceding species. Maxillary basis (Fig. 4J) prominent and blunt, with set of 4-5 large spinules in middle, increasing in length medially. Accessorial seta robust, with large spinules on both sides of the stem in proximal half, finely serrate along one side in distal half. Armature of proximal endopodite segment and terminal armature element on distal endopodite segment robust, with large spinules in proximal half and finely serrate in distal half on one side of the stem. Terminal seta on distal endpodite segment confluent with segment. Additional elements on distal segment sparsely serrate.

Leg 1-4 protopodite (Fig. 12 A–D). Frontal margin of praecoxa with short row of slender spinules near outer corner. Frontal surface of legs 1-4 coxa unadorned except for some minute spinules along distal margin. Caudal surface of leg 1 unadorned, of legs 2 and 3 with some slender spinules near outer proximal corner. Caudal surface of leg 4 coxa with a transverse row of spinules parallel to distal margin and some slender spinules near outer proximal corner. Intercoxal sclerite of legs 1-4 as in preceding species. Medial coxal seta present, pinnate and reaching beyond basis, attending distal margin of proximal endopodite segment in leg 1, and middle of proximal endopodite segment in legs 2 and 3. Medial element somewhat shorter in leg 4. Medial margin of basis of leg 1 crescent, hairy, and with pinnate element reaching beyond proximal endopodite segment. Spinules present at its insertion. Medial margin of basis of legs 2-4 crescent, produced distally in short triangular expansion. Hairy in legs 2-3, naked in leg 4. Outer seta on leg 1 basis as long as exopodite, and as long as first exopodite segment in legs 2-4.

Leg 1-4 rami 2-segmented with general appearance and armament distribution as in preceding species. Frontal and caudal surface of ramal segments unadorned. Proximal segment of leg 4 endopodite inflated caudally (Fig. 12D). Distal endopodite segment of leg 4 2.10-2.15 times longer than wide. Inner terminal spine as long as segment, and 1.8-2.1 times longer than outer spine. Medial setae on second endopodite segment equally long, not reaching beyond inner terminal spine.

Leg 5 (Fig. 11E) with ancestral segments confluent with pediger, represented as a semi-ovate expansion with a discreet truncation distally. Ancestral basal segment represented by a long setiform element. Ancestral distal segment represented by 2 elements: outer one setiform, half as long as medial spiniform element, both inserted on the distal discreet truncation.

Leg 6 (Fig. 11B) typically represented by 3 elements: outer one setiform, middle and medial ones dwarfed, hyaline and blunt. Valves unadorned. Genital complex with frontal and caudal parts of receptacles expanded. The former with undulate frontal margin, the latter with single medioventrally expansion. Copulatory pore leading to U-shaped duct (Fig. 11D). Lateral arms straight.

Male: Body narrower than female body (Fig. 10C). Prosome 1.5 times longer than urosome. Principal body flexure wide. Second urosomite (pediger 6) 2 times wider than long. Body length 795 μm (allotype, ranging from 744 to 817 in paratypes). Posterodorsal margins of prosomites and first urosomite narrow and straight. Posterior hyaline fringe margins of urosomite 2 narrow and serrate, of urosomites 3-5 wide and serrate. Anal somite with crescent, not expanded, anal operculum. Anal sinus smooth. Posterior margin of anal somite with uninterrupted row of spinules.

Caudal rami cylindrical with short triangular medial depression in anterior half. L/W-ratio: 2.7/1 (allotype, ranging from 2.7-3.0/1 in other male paratypes). Anterolateral seta short, pinnate, without spinules at insertion. Distolateral element shorter than ramus (ratio: 0.8-0.9/1) serrate along outer margin, pinnate along inner one. Spinules at insertion present. Terminal medial element longer and dorsal one longer than ramus:1.15-1.25/1 and 1.25-1.35, respectively. Dorsal seta articulating on basal part. Principal terminal setae with breaking plane and pinnate.

Antennule as described for Allocyclops cavicola in Fiers 2012. Mouthparts and legs 1-4 as in the female, except for leg 4 endopodite lacking expansion of caudal surface of the proximal segment. Leg 5 (Fig. 11C) with region representing ancestral distal segment more pronounced than in the female. Armature elements as in the female.

Leg 6 (Fig. 11C) represented as large, unadorned valve with caudally produced outer distal edge bearing 2 elements: outer one very short, setiform, medial long, spiniform and serrate.

Variability. Except for slight variation (less than 15 µm) in the body length and the L/W ratio of the caudal rami and its armament, no structural differences were observed in the type series nor in the other populations.