Morphological variation of Eucyclops elegans (Herrick, 1884) (Copepoda: Cyclopoida) in the Americas and comments on records of Eucyclops conrowae Reid, 1992 Author Mercado-Salas, Nancy F. Author Suárez-Morales, E. text Journal of Natural History 2014 2014-04-23 48 33 - 34 2007 2026 https://www.mendeley.com/catalogue/7a43c3e5-b04e-3cc0-a7fe-3bfeaa5f9f3e/ journal article 10.1080/00222933.2014.897766 1464-5262 5194101 Eucyclops conrowae Reid, 1992 ( Figures 6–7 ) Material examined National Museum of Natural History Smithsonian Institution , Washington DC : ♀ holotype (USNM- 251325) from Shark River Slough , Everglades National Park , Florida , USA , coll. R. Conrow , 1986, and one ♀ paratype (USNM-251327), same locality, date, and collector. Zooplankton Collection at El Colegio de la Frontera Sur , Chetumal : one ♀ (ECO-CH-Z-05294) from San José del Anteojo , Cuatro Ciénegas de Carranza , Mexico , coll. E. Walsh , 8 February 2006 and one ♀ (ECO- CH-Z-04829) from creek close to Túnel de Potrerillos , Rincón de Romos , Aguascalientes , Mexico , coll. M. Silva-Briano , 17 October 1992 . Figure 6. Eucyclops conrowae Reid, 1992 , adult female paratype (USNM-251327). (A) urosome, ventral; (B) antennules, segments 1–10; (C) antennules, segments 11–12; (D) antenna, frontal; (E) antenna basis, caudal; (F) labrum; (G) mandible; (H) maxillule; (I) maxilla. Figure 7. Eucyclops conrowae Reid, 1992 (A–F) adult female paratype (USNM-251327); (G) adult female holotype (USNM-251325). (A) P1, frontal; (B) P2, frontal; (C) P3, frontal; (D) intercoxal sclerite P3, caudal; (E) P4, frontal; (F) intercoxal sclerite and protopodite P4, caudal; (G) third exopod P4. We present a detailed description of the armature and ornamentation of the antennules, antennae and the fourth swimming leg so as to provide an updated overview of the structures and microcharacters currently used in the taxonomy of Eucyclops . A comparison with Mexican material is also provided. Description of selected characters Antennule ( Figure 6B–C ). 12-segmented, with finely denticulated membrane hyaline on segments 10–12. 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). Transversal row of strong spinules on first segment. Spine on sixth segment remarkably short, not reaching medial margin of seventh antennular segment. Antenna ( Figure 6D–E ). Coxa (no seta), basis (2s + Exp), plus three-segmented Enp (armature: 1s, 9s, 7s, respectively). Basis with following rows of spinules and number of elements on frontal surface: N3(6), N4(5), N5(9), N6(4), N17(10), N15(3), additional row between N15 and N17. Spinules on caudal surface as: N7(4), N8(4), N9 + N10(8), N11(4), N12(4), N13(4). Leg 4 ( Figure 7E–F ). Frontal surface of intercoxal sclerite with one transverse row of small spinules on middle margin (arrowed Figure 7E ), caudal surface with row I bearing strong and small spinules with a small gap in the middle section, Row II with strong and small spinules only on outer margins and Row III also bearing strong and small spinules, only on outer margins. Frontal surface of coxa with row of small spinules at insertion of basipod. Inner coxal spine with heterogeneous ornamentation; inner margin basally with long hairs and proximally with strong spinules, outer edge with three strong spinules on distal surface, naked basally. Caudal coxal surface with spinules formula: A–C + D–E–G–H. Remarks In the original description of E. conrowae , Reid (1992) advanced the shape of the seminal receptacle as one of the main distinguishing characters of the species. In the holotype the receptacle has the posterior expansion about twice as wide as the anterior expansion ( Reid 1992 , Figure 2c ). Our observations of one of the paratypes revealed a seminal receptacle with the typical shape of the serrulatus group ( Figure 6A ). A unique character that separates E. conrowae from other known American species is a remarkably long dorsal seta, which is as long as the caudal ramus. In other American species with short caudal rami like E. delachauxi Kiefer, 1926 , E. prionophorus Kiefer, 1931 , E. pseudoensifer Dussart, 1984 , E. cuatrocienegas Suárez-Morales and Walsh, 2009 and E. chihuahuensis Suárez- Morales and Walsh, 2009, the dorsal seta is always less than 0.6 times as long as the caudal rami. Eucyclops bondi Kiefer, 1934 is yet another congener with a long dorsal seta but its length does not exceed 0.8 times as long as the caudal ramus. The ornamentation of the antennary basis of E. conrowae is completed herein; on the frontal surface we found rows N3, N4, N5, N6, N15 and N 17 in both the holotype and paratype specimens, but we also found an extra row of spinules between rows N15 and N17. This additional row was observed also in specimens of E. elegans from Mexico and it is present in E. angeli Gutiérrez-Aguirre and Cervantes-Martínez, 2013 in Gutiérrez-Aguirre et al. 2013 from Chiapas , Mexico . This extra row of spinules seems to be a character shared by species of Eucyclops from Mexico , as we will report in more detail and with additional data in a forthcoming paper. It is important to mention that rows N1 and N2 were absent in the holotype and paratype specimens of E. conrowae , thus clearly showing that it is not assignable to the serrulatus group ( Alekseev and Defaye 2011 ). The ornamentation of the coxal plates of the swimming legs, especially that of P4, is among the characters that have been pointed out as informative in recent taxonomic works on Eucyclops ( Alekseev et al. 2006 ; Alekseev and Defaye 2011 ; Gutiérrez-Aguirre et al. 2013 ). In E. conrowae the P4 coxal plate presents a unique spinulation pattern on its frontal surface, with one continuous row of strong spinules along the middle margin, thus differing from the Mexican specimens examined in which this row is clearly divided into two groups, one at each side of the sclerite. The pattern on the caudal surface has the ornamentation usually found in Eucyclops , bearing rows I–III. Among the groups of elements of the caudal coxal surface, row J is absent in E. conrowae . The presence of modified setae of the swimming legs appears to be a frequent character in some species of Eucyclops , but the highly modified setae on the third exopodal segment of P4 of E. conrowae are unique, as mentioned by Reid (1992) . In many specimens from Mexico these setae are modified but none of them are heavily sclerotized as in the type material of E. conrowae ; thus, specimens assigned to E. conrowae should be reviewed in order to confirm the presence of this species in the country.