Eucyclops mittmanni, Mercado-Salas & Suárez-Morales & Silva-Briano, 2015

Mercado-Salas, Nancy F., Suárez-Morales, Eduardo & Silva-Briano, Marcelo, 2015, Taxonomic revision of the Mexican Eucyclops (Copepoda: Cyclopoida) with comments on the biogeography of the genus, Journal of Natural History 50, pp. 25-147 : 112-119

publication ID	https://doi.org/ 10.1080/00222933.2015.1061715
publication LSID	lsid:zoobank.org:pub:2F320DE0-FF96-4E5F-8520-586303082E09
DOI	https://doi.org/10.5281/zenodo.4332573
persistent identifier	https://treatment.plazi.org/id/397AD47D-FFA7-FFAF-A643-FEAEFD6C763C
treatment provided by	Carolina
scientific name	Eucyclops mittmanni
status	sp. nov.

Treatment

Eucyclops mittmanni sp. nov. Mercado-Salas and Suárez-Morales ( Figures 55 – 60 View Figure 55 View Figure 56 View Figure 57 View Figure 58 View Figure 59 View Figure 60 )

Material examined

Holotype. Adult ♀ specimen dissected, mounted in glycerin sealed with Entellan (ECO-CH-Z-04948).

Paratypes. Seven adult ♀♀ undissected ethanol-preserved (90%) (ECO-CH-Z-04949). Samples from type locality collected 18 February 1989 by Marcelo Silva-Briano.

Type locality

Creek at Sierra Fria 21 km north of Village La Labor, Calvillo, Aguascalientes, Mexico.

Etymology

This species is warmly dedicated to Dr. Hans-Walter Mittmann (Staatliches Museum für Naturkunde Karlsruhe, Germany) who is in charge of the Kiefer Collection.

Distribution

Aguascalientes.

Description

Female. Habitus as in Figure 57A View Figure 57 . Average length excluding caudal setae = 1216 µm. Whole body (caudal ramus included) ornamented with small cuticular pits. Prosome representing 58% of total body length, symmetrical in dorsal view. Prosomal fringes finely serrate dorsally. Urosomal fringes strongly serrate. Genital double somite symmetrical ( Figure 57B View Figure 57 ), representing 10% of total body length; proximal third of genital double somite slightly expanded laterally. Seminal receptacle with rounded lateral arms on posterior margin, typical of the serrulatus -complex. Length/ratio of caudal ramus = 7.5; inner margin of caudal ramus naked; strong spines covering 69% with respect to the total length of ramus. Dorsal seta (VII) 0.5 times as long as caudal ramus and 0.8 times as long as outermost caudal seta (III). Ratio of innermost caudal seta (VI)/ outermost caudal seta (III) = 0.8. Lateral caudal seta (II) inserted at 78% of caudal ramus.

Antennule ( Figures 55B View Figure 55 , 57F View Figure 57 , 58 View Figure 58 A-B). Tip reaching posterior margin of fourth pediger. Armature per segment as follows: 1(8s), 2(4s), 3(2s), 4(6s), 5(4s), 6(1s+1sp), 7(2s), 8(3s), 9(2s+1ae), 10(2s), 11(3s), 12(8s). One transverse row of spinules on first segment. Spine on sixth segment not reaching medial margin of seventh segment.

Antenna ( Figures 55C–E View Figure 55 , 58C–E View Figure 58 ). Coxa (unarmed), basis (2s+Exp), plus three-segmented Enp(1s, 9s, 7s, respectively). Basis with row of spinules on frontal surface: N1(VI),

N2(VI), N3(9), N4(8), N5(9), N15(9), N17(15); on frontal surface: N7(5), N8(5) N9+N10(5), N11(7), N12(10), N13(6), N14(7), N16(5), N19(5), N20(8), N21(5). Caudal surface of first Enp with B2(13) and B3(5).

Leg 1 ( Figures 56A–B View Figure 56 , 59A–B View Figure 59 ). Frontal surface of intercoxal sclerite with row I bearing long spinules on each side; caudal surface with row I continuous, bearing 15 minute spinules, row II continuous, with 20 minute spinules, distal margin with two rounded, chitinised projections. Inner coxal seta biserially setulated, caudal coxal surface with spinule formula = A-B-C. Inner basal seta (basipodal spine) not reaching middle margin of Enp3, 0.7 times as long as Enp. Length/width ratio Enp3 = 1.8, apical spine of Enp3 being 1.2 times as long as Enp3.

Leg 2 ( Figures 56C–D View Figure 56 , 59C View Figure 59 ). Frontal surface of intercoxal sclerite with row I bearing spinules arranged in circular pattern on each side; caudal surface with row II continuous, with 20 minute spinules, row I absent, distal margin with two rounded, chitinised projections. Inner coxal seta biserially setulated, caudal coxal surface with spinule formula = A-B-C-D. Small spinules along insertion of basipodite (frontal surface). Length/ width ratio of Enp3 = 2.7, apical spine of Enp3 as long as segment (Enp3). No modified setae present.

Leg 3 ( Figure 56E–F View Figure 56 ). Frontal surface of intercoxal sclerite with row I armed with long spinules arranged in a circle on each side, all spinules about the same length; caudal surface of intercoxal sclerite with row I bearing 8 – 10 small spinules on each side (small gap in the middle), row II continuous, with minute spinules (27 – 30); row III continuous, with 25 – 28 long spinules, spinules adjacent to outer margin longer than medial ones. Distal margin with two rounded, chitinised projections. Coxa with strong, biserially setulated coxal seta, ornamented basally with long hairs and distally with strong spinules. Caudal coxal surface with spinule formula = A-B-C. Length/width ratio of Enp3 = 2.7, apical spine of Enp3 as long as segment (Enp3). No modified setae present.

Leg 4 ( Figures 56G–H View Figure 56 , 59C–E View Figure 59 ). Distal margin of intercoxal sclerite with two low, rounded, chitinised projections. Frontal surface with row I bearing long hairs arranged

in semicircular pattern; caudal surface of intercoxal sclerite with row I bearing 10 – 11 strong long spinules on each side with small gap between, row II discontinuous, with long hair spinules adjacent to outer margins and three strong, long spinules in middle section. Row III with long hair – spinules in outer margins. Frontal surface of coxa with spinules at insertion of Bsp. Inner coxal spine with heterogeneous ornamentation; proximal inner margin with long hairs, distally with spinules; outer margin with three spinules on distal surface and basally with hairs, gap in middle margin. Caudal coxal surface with spinule formula = A-B-C + D-E-F-H-J. Length/width ratio Enp3 P4 = 3.7, length ratio inner spine of Enp3/length Enp3 = 1.0; length ratio outer spine of Enp3/ length Enp 3 = 0.8; length ratio inner/outer spines Enp3 = 1.3. Lateral seta of Enp3 inserted at 62% of segment. No modified setae in Enp and Exp.

Leg 5 ( Figures 59F View Figure 59 , 60F View Figure 60 ). Free segment subrectangular, 1.6 times longer than wide, bearing one inner spine and two setae; medial seta 1.6 times longer than outer seta and 1.1 times longer than inner spine. Inner spine 2.7 times longer than segment.

Remarks. Eucyclops mittmanni sp. nov. is closely related to E. elegans ; it is possible that some Mexican and North American records of the latter species are now assignable to E. mittmanni sp. nov. Most of the records of E. elegans ( Suárez-Morales, 2004) have been based upon the length of its caudal ramus, which is remarkably longer than that of closely related species like E. pectinifer and E. serrulatus . This apparently unique character might have prevented further analysis of specimens from different geographic areas or Mexico. In the recent redescription of E. elegans ( Mercado-Salas and Suárez-Morales, 2014b) from material deposited in different collections and including specimens from different geographic areas of the continent, differences were found between North American (NA) and South American (SA) populations of this species. It is suggested that the NA and SA specimens could represent two independent species. Eucyclops mittmanni sp. nov. differs from both forms of E. elegans by a combination of different characters, but, as expected, it appears to be more closely related to the NA form of E. elegans . Morphometrical values do not differ among these species, but it is important to mention that E. elegans NA (body length = 1061 µm) and E. elegans SA (1100 µm) are both slightly smaller than E. mittmanni sp. nov. (1216 µm). The new species shares with the SA populations a round and smooth anal operculum; the same structure is also rounded but serrate in the NA form. Some of the main differences observed between both the SA and NA forms of E. elegans and E. mittmanni sp. nov. are related to the ornamentation pattern of the antennal basis. In the three forms the frontal surface has the same pattern except for E. elegans NA, which shows N18, and in E. mittmanni sp. nov. N1 and N2 are completely separated, thus contrasting with the fused condition observed in the two forms of E. elegans . The ornamentation pattern on the caudal surface also differs among both forms of E. elegans and E. mittmanni sp. nov.: in E. elegans SA rows N7, N14, N22 are absent, while in E. elegans NA and E. mittmanni sp. nov. they are present. Like many other Mexican congeners, E. elegans NA bears row N18, a character that is absent in E. mittmanni sp. nov. The new species is the only one among the Mexican Eucyclops that has rows N19 and N20; it shares the presence of N20 with E. chihuahuensis only. The ornamentation of P1 and P2 intercoxal sclerites is similar in the three forms but some differences were observed in the P3 caudal surface. In E. elegans NA row I bears long hair – spinules, a character shared with other Mexican species of Eucyclops , but divergent from both E. mittmanni sp. nov. and E. elegans SA in which row I has small strong spinules, also present in E. defayeae sp. nov. and E. cuatrocienegas . In the new species, row III has remarkably long, strong spinules that are shorther in E. elegans NA. The ornamentation of the caudal surface of the P4 coxa and intercoxal sclerite is another useful character to separate the three forms: in E. mittmanni sp. nov. and E. elegans SA row II is divided into three sections, two close to the outer margins and one bearing long spinules in the middle section, whereas this row is continuous and bears small but strong spinules in E. elegans NA. The coxal surface of P4 is more ornamented in the new species than in the two forms of E. elegans , and rows B, C and E are present in E. mittmanni sp. nov. and are absent in E. elegans , but E. elegans has row G, absent in the new species.