Eucyclops angeli Gutierrez-Aguirre & Cervantes-Martinez

Gutierrez-Aguirre, Martha Angelica, Mercado-Salas, Nancy Fabiola & Cervantes-Martinez, Adrian, 2013, Description of Eucyclops tziscao sp. n., E. angeli sp. n., and a new record of E. festivus Lindberg, 1955 (Cyclopoida, Cyclopidae, Eucyclopinae) in Chiapas, Mexico, ZooKeys 351, pp. 1-30 : 8-14

Eucyclops angeli Gutierrez-Aguirre & Cervantes-Martinez sp. n. Figs 5-9

Material examined.

Holotype: Adult ♀ specimen dissected, mounted in glycerin sealed with Entellan (ECO-CH-Z- 8967). Allotype: Adult ♂, dissected, mounted in glycerin sealed with Entellan (ECO-CH-Z-8968). Paratypes: Eight adult ♀♀ undissected ethanol-preserved (90%) (ECO-CH-Z-8969); five adult ♀♀ and one adult ♂ undissected, ethanol preserved (90%) (MNHN-IU-2013-5970); four adult ♀♀, undissected, ethanol preserved (90%) (CNCR 27841). Samples from type locality collected at 13. January. 2001 by A. Cervantes-Martínez, M. A. Gutiérrez-Aguirre and M. Elías-Gutiérrez.

Type locality.

Grassland near ECOSUR in San Cristóbal de las Casas City (Chiapas, México) (16°43'43"N, 92°38'14"W). At sampling the maximum depth was 1.48 m, the water temperature 21.5°C, and the dissolved oxygen 8.1 mg l-1.

Etymology.

This species is dedicated to Angel Cervantes Rivas, the first son of A C-M.

Description.

Female: Habitus as in Fig. 5A; 600 µm of total body length excluding caudal setae. Prosome expanded at first and second somite, representing 58% of total body length, symmetrical in dorsal view (Figure 5A). Prosomal fringes serrated dorsally (Figure 5B); fourth prosomite with long, lateral, hair-setae (Fig. 5C). Five-segmented urosome, relatively elongated; first urosomite with long spinules on lateral margin; urosomal fringes strongly serrated (Fig. 5D). Posterior margin of anal somite with large spinules on ventral and dorsal surfaces, except for the medialmost section. Genital double-somite symmetrical, lateral arms of anterior part of seminal receptacle rounded; posterior part forming sinuous sac (Fig. 5D). Anal somite subequal in length to preanal somite and around 60% of caudal ramus length; with hair-setae in anal opening (Fig. 5D, E). Length/width ratio of caudal ramus 2.1; inner margin of caudal ramus naked, strong spines on lateral margin (serra) extending 62% of ramus length (Figure 5D). Dorsal seta (VII) relatively short, 0.83 times the length of caudal ramus, and 1.1 times as long as outermost terminal caudal seta (III). Innermost caudal seta (VI) 1.5 as long as outermost caudal seta (III). Lateral caudal seta (II) inserted at 71.6% of caudal ramus. Lateral seta (II) is 0.4-0.5 the length of outermost caudal seta (III). All terminal caudal setae plumose. Relative lengths of terminal caudal setae from outermost caudal seta to innermost caudal seta: 1.0: 3.9: 7.5: 1.2 (Fig. 5E).

Antennule (Fig. 6A): 12-segmented, tip reaching from middle to distal margin of second prosomite; smooth hyaline membrane on segments 10-12. The length ratio of segments 12/11 is 1.1. Armament per segment as follows (s= seta, ae= aesthetasc, sp= spine): 1(8s); 2(4s); 3(2s); 4(6s); 5(4s); 6(1s+1sp); 7(2s); 8(3s); 9(2s+1ae); 10(2s); 11(2s+1ae); 12(7s+1ae). Row of spinules on first segment: inner spinules shorter than outer spinules. Long spine on sixth segment, reaching the distal third of seventh antennular segment.

Antenna (Fig. 6B, C): Coxa (no seta), basis (2 s + 1 s representing Exp), plus 3-segmented Enp (first to third endopodite with 1, 9 and 7 setae respectively). Basis ornamented with: N1 (5 hair-setae), N2 (3 hair-setae), and N3, N4, N5, N17 (Fig. 6C) on frontal surface; and N7, N8, N10, N11, N12, N12', N13, N15, and N16 on caudal surface (Fig. 6B). First to third endopodal segments with dense rows of spinules along lateral margin; Enp1 with additional row of 2 spinules on caudal surface (arrowed in Fig. 6B).

Labrum (Fig. 6D): Distal margin toothed. Ventral surface with long hair-setae. Two rounded lateral protuberances bearing spinules.

Mandible (Fig. 6E): With nine teeth on gnathobase, the innermost bi-toothed. Innermost margin with one spinulose seta. Palp with two long and one short setae. Three rows of tiny spinules next to palp.

Maxillule (Fig. 6F): Praecoxal arthrite with 3 chitinized claws and one spinulose seta on caudal side. Inner margin with two biserially plumose setae and four spiniform setae. Praecoxal surface naked. Palp naked, with Enp (3 long setae: one smooth, plus two plumose), Exp (3 long setae), and Bsp (with one plumose seta) (Fig. 6F).

Maxilla (Fig. 6G): Praecoxa and coxa partially fused. Praecoxal endite with two armed setae. Coxa naked and with two endites: proximal endite bearing one biserially plumose seta, distal endite with one long, plumose seta plus one short smooth seta. Claw-like basal endite with row of spinules on inner margin; one small seta inserted on caudal surface, and one chitinized armed seta inserted in front of claw-like endite. Endopod one-segmented bearing four smooth, long setae plus one plumose seta.

Maxilliped (Fig. 6H): Syncoxa with three setae bearing spiniform setules. Basis with two subequal setae and 9 spinules frontally. Two rows of acute spinules, each with 8 elements, arranged in semi-circular pattern on caudal surface. Endopod two-segmented: Enp1 with 4 basal spinules and one long seta fused to segment; Enp2 with three setae, longest seta biserially plumose and fused to Enp2.

Legs 1-4: With three-segmented Exps and Enps; intercoxal sclerites ornamented on frontal and caudal surfaces (Fig. 7). Armature formula of P1-P4 as in Table 3.

Leg 1 (Fig. 7A): Intercoxal sclerite armed with two arched rows of long spinules frontally and one row of tiny spinules caudally (Fig. 7A). Frontal surface of coxa with row of long spinules along lateral margin; long, feathered seta at mediodistal angle. Basis with one delicate outer seta, and one inner armed spine as long as Enp. Inner margin of Bsp hairy. Inner spine of Bsp with small basal spines, long setules proximally, and spine-like setules distally (Fig. 7A). Setae of Enp and Exp of P1 are unmodified, and regularly plumose in both edges (Fig. 7A). Caudal surface of coxa with four groups of spinules and one row of hair-like spinules near medial margin (Fig. 7B).

Leg 2 (Figs 7 C–E): Intercoxal sclerite with two rows of hair-setae on each of the two rounded projections on frontal surface (Fig. 7C), and three groups of spinules on caudal surface (Fig. 7E). Coxa with one row of long spinules along outer margin and two groups of spinules on distal margin on frontal surface (Fig. 7C). Lateral margin of coxa with two groups of long spinules, one group of short spinules, and one row of hair-setae in medial position on caudal surface (Fig. 7D). Armed coxopodal spine at mediodistal angle. Basis with one outer seta, inner margin hairy. All setae of Enp and Exp of P2 not constricted, plumose in both edges (Fig. 7C).

Leg 3 (Fig. 7 F–I): All setae on Exp and Enp as described in P2, except for the two distalmost setae of Exp3P3, which have very short setules along outer (constricted) edge (Fig. 7F). Caudal surface of P3 coxa with one row of tiny spinules along outer margin, one group of long spinules, one group of short spines, and one row of medial hair-setae (Fig. 7G). Caudal surface of intercoxal sclerite with three rows of hair- setae (Fig. 7I). On frontal surface, the ornamentation of coxa, Bsp, and intercoxal sclerite of P3, is similar to those in P2 (Fig. 7H).

Leg 4 (Fig. 7J, K): Caudal surface of coxa with spinule ornamentation consisting of groups A–J. Coxal spine (inner seta) with heteronomous setulation: proximally with long setules, distally with spine-like setules; outer edge of coxal spine with a gap (Fig. 7J). Basis with delicate outer seta, and short hairs on inner margin. Three setae of Exp3P4 with constricted outer edge, and with short setules. Enp3P4 1.8 times as long as wide; inner spine 1.3 as long as outer spine and 1.3 as long as segment; outer spine 0.93 as long as segment. Caudal surface of intercoxal sclerite of P4 armed with 7 long denticles in position I, and long hair-setae in position II and III (Fig. 7J). Frontal surface of intercoxal sclerite of P4 with four rows of short spinules (Fig. 7K).

Leg 5 (Fig. 5F): One free segment 1.4 times longer than wide; bearing one inner spine and two setae. Outer seta shorter than inner spine, relative lengths from outer seta to inner spine: 0.5: 1.6: 1 (Fig. 5F). Inner spine 2.0 times longer than segment.

Male: Habitus as in Fig. 8A; body length excluding caudal setae= 540-580 µm (n=4) average body length=552.9 ± 15.56. Prosome symmetrical in dorsal view, representing 60-63% of total body length (Fig. 8A). Fourth prosomite with two spines, one spine on ventral margin, and one spine on posterior margin (Fig. 8B). Six-segmented urosome, relatively elongated; first urosomite naked on lateral margin (Fig. 8C); posterior margin of anal somite with a continuous (dorsally and ventrally) row of spinules (Fig. 8A, D). Anal region armed with two parallel rows of hair-setae; anal operculum slightly rounded and smooth (Fig. 8D). Caudal ramus 2.1 ± 0.07 times longer than width (n=4); medial margin of caudal ramus naked, strong spines at insertion of lateral caudal seta (Fig. 8D). Innermost caudal seta (VI) 1.0-1.14 times longer than caudal ramus (n=3). Relative lengths of terminal caudal setae from outermost (III) to innermost (VI): 1.0: 5.7-6.4: 10.8-12.0: 1.45-1.6. Lateral caudal seta (II) 0.64-0.83 the length of outermost caudal seta (III) (Fig. 8D).

Antennule (Fig. 8E): 16-segmented, between segments 14-15 is the geniculation; armament per segment as follows (s= seta, modified seta= ms, ae= aesthetasc, sp= spine): 1(6s+2ms+1ae); 2(3s+1ms); 3(1s+1ms); 4(1s+1ms+1ae); 5(2s+1ms); 6(1s+1ae); 7(1s); 8(2s); 9(2s); 10(2s); 11(1s); 12(1s); 13(3s); 14(0); 15(1s); 16(9s). Row of spinules on first segment: inner spinules shorter than outer spines.

Antenna: As in female except for that the spinule groups N7, N13, and N16 are absent on caudal surface of antennal Bsp (Fig. 8F). Basis ornamented with: N1 (4 hair setae), N2 (2 hair setae) and spinules in groups N3, N4, N5, and N17 on frontal surface (Fig. 8G).

Labrum, mandible, maxillule, maxilla, and maxilliped as in female.

Legs 1-4: Exps and Enps three-segmented. Intercoxal sclerites armed as in Fig. 9 A–C, F. Setation formula of swimming legs as in female (Table 3).

Leg 1 (Fig. 9A): Intercoxal sclerite armed with two rows of tiny spinules on caudal surface. Ornamentation of Bsp, Enp, and Exp, as in female. Caudal surface of coxa with three groups of spinules and one row of hair-setae.

Leg 2 (Fig. 9B): As in female, except for that intercoxal sclerite is naked on caudal surface, yet with two arched rows of long spinules on frontal surface.

Leg 3 (Fig. 9 C–E): Modified, intercoxal sclerite with rows of spinules caudally, and rows of hair-setae frontally (Fig. 9C). Two distalmost setae of Exp3P3 and Enp3P3 with constricted outer edges, and very short setules (Fig. 9D, E). Coxa and Bsp as described in female (Fig. 9C).

Leg 4 (Fig. 9 F–I): Coxa, basis, and intercoxal sclerite as in female; except for that entire outer margin of coxal seta is naked (Fig. 9F, G). Enp3P4: 2.07-2.25 (n=2) times as long as wide; inner apical spine 1.24-1.31 (n=2) as long as outer spine and 1.08-1.26 (n=2) times as long as segment (Fig. 9H). Two distal setae of Exp3P4 modified: chitinized, both edges constricted, and bearing short setules on outer edge (Fig. 9I).

Leg 5 (Fig. 9J): One free segment, 1.6 times longer than wide; and bearing three elements of which outer seta is slightly longer than that in female (subequal in length to inner spine) (Fig. 9J). Inner spine 1.8 times as long as segment.

Leg 6 (Fig. 9J): Represented by a small, low plate near lateral margin of genital somite, armed with one inner spine, which is 1.7-1.87 times longer than outer seta, and 1.2-1.6 times longer than median seta. Inner spine of sixth leg reaching the distal margin of fourth urosomite.