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First record of the freshwater copepod Eucyclops titicacae Kiefer, 1957, new rank (Copepoda, Cyclopoida) in Colombia

Abstracts

The freshwater cyclopoid copepod Eucyclops titicacaeKiefer, 1957KIEFER, F. 1957. Freilebende Ruderfüsskrebse (Crustacea Copepoda) des Titicaca sees. Veröff. Zool. Staatssamml. Muench. 4:125-150., new rank, was previously known as a subspecies of E. neumani (Pesta, 1927PESTA, O. 1927. Ein Beitrag zur Kenntnis der Copepodenfauna von Argentinien. Zool. Anz. 73(3-4):67-80.). Hitherto, it was recorded only from Lake Titicaca in Peru and Lake Valencia in Venezuela. This species is here recorded from Laguna Navío Quebrado, La Guajira, northern Colombia. This is the first record of E. titicacae in Colombia and the third locality in which this species has been reported from. We provide comparative data on the morphology of this copepod. The Colombian specimens have the combination of diagnostic features of E. neumani titicacae as reported in both the original description and subsequent taxonomical accounts, including: 1) spinules on caudal rami not reaching halfway the outer margin; 2) caudal rami length/width ratio= 6.0; 3) length/width ratio of third endopodal segment of fourth leg=1.66; 4) inner spine of fifth leg being shorter than the two adjacent setae. The consistent morphologic differences and the isolation of E. neumani titicacae with respect to E. neumani neumani, each related to a different biogeographic subregion in South America, support the notion that these are two separate species, E. neumani and E. titicacae. Considering this interesting addition, the number of species of Eucyclops known from Colombia increases to 8; a key for the identification of these species is also provided.

continental copepods; taxonomy; freshwater zooplankton; Laguna Navío Quebrado; Colombia; distribution


El copépodo ciclopoide de agua dulce Eucyclops titicacaeKiefer, 1957KIEFER, F. 1957. Freilebende Ruderfüsskrebse (Crustacea Copepoda) des Titicaca sees. Veröff. Zool. Staatssamml. Muench. 4:125-150., nuevo rango, se conocía previamente como una subespecie de E. neumani (Pesta, 1927PESTA, O. 1927. Ein Beitrag zur Kenntnis der Copepodenfauna von Argentinien. Zool. Anz. 73(3-4):67-80.). Se había registrado solamente en los lagos Titicaca en Perú y Valencia en Venezuela. Esta especie se registra ahora en la Laguna Navío Quebrado, La Guajira, norte de Colombia. Este es el primer reporte de E. titicacae en Colombia y la tercera localidad en cual esta especie ha sido reportada. Se ofrece información comparativa sobre la morfología de este copépodo. Los especímenes de Colombia tiene la combinación de caracteres diagnósticos de E. neumani titicacae como se presentaron en la descripción original y en trabajos taxonómicos subsecuentes, incluyendo: 1) las espínulas de la rama caudal no alcanzan la mitad del margen externo, 2) la relación largo/ancho de la rama caudal = 6.0, 3) la relación longitud/ancho del tercer segmento endopodal de la cuarta pata = 1.66, 4) la espina interna de la quinta pata es más corta que las dos setas adyacentes. Las consistentes diferencias morfológicas y el aislamiento de E. neumani titicacae con respecto a E. neumani neumani, que se distribuyen en subregiones biogeográficas distintas en América del Sur, apoyan la idea de que se tratan de dos especies separadas, E. neumani y E. titicacae. Considerando esta interesante adición, el número de especies de Eucyclops conocidas para Colombia se incrementa a 8; se proporciona una clave para la identificación de estas especies.

copépodos continentales; taxonomía; zooplancton de agua dulce; Laguna Navío Quebrado; Colombia; distribución


Introduction

The freshwater cyclopoid copepod Eucyclops neumani (Pesta, 1927PESTA, O. 1927. Ein Beitrag zur Kenntnis der Copepodenfauna von Argentinien. Zool. Anz. 73(3-4):67-80.), described originally from Argentina, is known to contain two subspecies, E. neumani neumani (Pesta, 1927PESTA, O. 1927. Ein Beitrag zur Kenntnis der Copepodenfauna von Argentinien. Zool. Anz. 73(3-4):67-80.), distributed mainly in Argentina, Paraguay and Brazil (Reid 1985REID, J.W. 1985. Chave de identificação e lista de referencias para as espécies continentais sulamericanas de vida livre da ordem Cyclopoida (Crustacea, Copepoda). Bolm. Zool., Univ. São Paulo 9:17-143., Dussart & Frutos 1986DUSSART, B.H. & FRUTOS, S.M. 1986. Sur quelques Copépodes d'Argentine 2. Copépodes du Paraná Medio. Rev. Hydrobiol. Trop. 19(3-d): 241-262., Silva 2008SILVA, W.M. 2008. Diversity and distribution of the free-living freshwater Cyclopoida (Copepoda: Crustacea) in the Neotropics. Braz. J. Biol. 68(4, Suppl.):1099-1106. PMid:19197479. http://dx.doi.org/10.1590/S1519-69842008000500016
http://dx.doi.org/10.1590/S1519-69842008...
, Mercado-Salas et al. 2012MERCADO-SALAS, N., POZO, C., MORRONE, J. & SUÁREZ-MORALES, E. 2012. Distribution patterns of the American species of the freshwater genus Eucyclops (Copepoda: Cyclopoida). J. Crust. Biol. 32:457-464. http://dx.doi.org/10.1163/193724012X626502
http://dx.doi.org/10.1163/193724012X6265...
) and E. neumani titicacaeKiefer 1957KIEFER, F. 1957. Freilebende Ruderfüsskrebse (Crustacea Copepoda) des Titicaca sees. Veröff. Zool. Staatssamml. Muench. 4:125-150., originally described from Lake Titicaca (Peru and Bolivia) (Kiefer 1957KIEFER, F. 1957. Freilebende Ruderfüsskrebse (Crustacea Copepoda) des Titicaca sees. Veröff. Zool. Staatssamml. Muench. 4:125-150.). According to Alekseev & Defaye (2011)ALEKSEEV, V. & DEFAYE, D. 2011. Taxonomic differentiation and world geographical distribution of the Eucyclops serrulatus group (Copepoda, Cyclopidae, Eucyclopinae). In Studies on Fresh-water Copepoda: a Volume in Honour of Bernard Dussart (D. Defaye, E. Suárez-Morales & C. Von Vaupel Klein, eds.). Crustaceana Monographs 16, E.J. Brill, Amsterdam, p.41-72., E. neumani titicacae is a member of the E. serrulatus species group, comprising species with 12-segmented antennules bearing a smooth hyaline membrane on the three distal segments, caudal ramus of moderate length (3.5-7.0 length/width ratio), a strong inner spine of leg 5, and one or two groups of hairs on the distal margin of the antennary basipodite, among other characters.

As stated by Silva (2008)SILVA, W.M. 2008. Diversity and distribution of the free-living freshwater Cyclopoida (Copepoda: Crustacea) in the Neotropics. Braz. J. Biol. 68(4, Suppl.):1099-1106. PMid:19197479. http://dx.doi.org/10.1590/S1519-69842008000500016
http://dx.doi.org/10.1590/S1519-69842008...
, E. neumani titicacae was previously known to be restricted to its type locality, Lake Titicaca, where it has also been recorded as E. neumani (Ueno 1966UENO, M. 1966. Zooplankton of Lake Titicaca on the Bolivian side. Hydrobiologia 29:547-568. http://dx.doi.org/10.1007/BF00189910
http://dx.doi.org/10.1007/BF00189910...
). However, it was realized that an older record of “Cyclops serrulatus” published by Pearse (1922)PEARSE, A.S. 1922. Crustacea of Lake Valencia, Venezuela. Proc. U.S. Acad. Sci. 59:459-462. from Lake Valencia, Venezuela, was assignable to E. neumani titicacae (Reid 1985REID, J.W. 1985. Chave de identificação e lista de referencias para as espécies continentais sulamericanas de vida livre da ordem Cyclopoida (Crustacea, Copepoda). Bolm. Zool., Univ. São Paulo 9:17-143.). It was subsequently reported, also as E. neumani by Infante (1978)INFANTE, A. 1978. The zooplankton of Lake Valencia (Venezuela). I: Species composition and abundance. Verh. Internat. verein. Limnol. 20:1186-1191. and Infante et al. (1979)INFANTE, A., RIEHL, W. & SAUNDERS, J.D. 1979. Los copépodos del Lago de Valencia, Venezuela. Acta Científ. Venez. 30:224-233. from the same Venezuelan lake (Reid 1985REID, J.W. 1985. Chave de identificação e lista de referencias para as espécies continentais sulamericanas de vida livre da ordem Cyclopoida (Crustacea, Copepoda). Bolm. Zool., Univ. São Paulo 9:17-143.). These two large Neotropical lakes (Titicaca and Valencia) are the only sites in which this subspecies has been observed. During a biological survey of the lagoon system in the La Guajira region in northern Colombia, littoral plankton samples were obtained. Female specimens of a cyclopoid copepod assignable to E. neumani titicacae were collected. We report this finding together with a morphological comparison with E. n. neumani to support this interesting record in Colombia.

Material and Methods

A limnological survey of the Laguna Navío Quebrado (11° 25′ N, 75° 5′ W), in the department of La Guajira, northern Colombia was carried out during the dry season (April, 2012). A total of three adult female specimens of Eucyclops neumani titicacae were found in a sample taken with a plankton net (0.4 mm mesh size) hauled among submerged macrophytes at a depth of 0.5 m. The pH of the water was 7.6. The original samples were fixed and preserved in 70% ethanol. The specimen was dissected and the taxonomically relevant appendages were mounted in semi-permanent slides that were deposited in the Museo de Colecciones Biológicas of the Universidad Del Atlántico, Barranquilla-Atlántico, Colombia (UARC). The appendages were photographed using a Kodak Easy Share C140 digital camera adapted to a compound microscope; drawings were prepared with a camera lucida. The specimens were deposited in the collection of the Museum of the Universidad del Atlántico, in Barranquilla, Colombia (UARC) and in the first author's collection. The identification key presented in this contribution was prepared following the species discriminating characters proposed by Reid (1985)REID, J.W. 1985. Chave de identificação e lista de referencias para as espécies continentais sulamericanas de vida livre da ordem Cyclopoida (Crustacea, Copepoda). Bolm. Zool., Univ. São Paulo 9:17-143. and Suárez-Morales et al. (2004).

Results and Discussion

Order Cyclopoida BURMEISTER, 1835

Family Cyclopidae RAFINESQUE, 1815

Subfamily Eucyclopinae KIEFER, 1927

Genus Eucyclops Claus, 1893

Eucyclops titicacaeKiefer, 1957KIEFER, F. 1957. Freilebende Ruderfüsskrebse (Crustacea Copepoda) des Titicaca sees. Veröff. Zool. Staatssamml. Muench. 4:125-150., new rank

Material examined: Three adult female specimens collected April, 2012 from Laguna Navío Quebrado (11° 25′ N, 75° 5′ W), altitude: 0 m, La Guajira, northern Colombia, plankton net of 45µm mesh size, among submerged macrophytes. Specimens dissected, semi-permanent slides (UARC88M-95M).

Morphology. Body length of female specimens: 0.98-1.03 mm (Figure 1A). Our specimens are slightly smaller than those from Lake Titicaca and Lake Valencia (females 1.0-1.27 mm). Body shape and proportions as described by Kiefer (1957)KIEFER, F. 1957. Freilebende Ruderfüsskrebse (Crustacea Copepoda) des Titicaca sees. Veröff. Zool. Staatssamml. Muench. 4:125-150.. The specimen examined bears the diagnostic features of E. neumani titicacae, as follows:

Figure 1.
Eucyclops neumani titicacae from La Guajira, Colombia. Adult female. A. habitus, dorsal view. B. antennule. C. distal three antennulary segments. D. same, showing smooth hyaline membrane (arrowed) on segments 10-12; E. antenna; F. antennary ornamentation showing combined caudal and frontal surfaces; nomenclature of spine groups follows Alekseev & Defaye (2011)ALEKSEEV, V. & DEFAYE, D. 2011. Taxonomic differentiation and world geographical distribution of the Eucyclops serrulatus group (Copepoda, Cyclopidae, Eucyclopinae). In Studies on Fresh-water Copepoda: a Volume in Honour of Bernard Dussart (D. Defaye, E. Suárez-Morales & C. Von Vaupel Klein, eds.). Crustaceana Monographs 16, E.J. Brill, Amsterdam, p.41-72..

Antennules with 12 segments (Figure 1B), armature 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(3s), 12(8s). The proportional length of the last three antennulary segments are, from proximal to distal: 24.2: 35.7: 40.1 (Figure 1C), similar to the proportions of the original description (25.8: 33.6: 40.6) (Kiefer 1957KIEFER, F. 1957. Freilebende Ruderfüsskrebse (Crustacea Copepoda) des Titicaca sees. Veröff. Zool. Staatssamml. Muench. 4:125-150., fig. 12). The three distal segments (10-12) have a smooth hyaline membrane that is typical among members of the E. serrulatus-species group (Alekseev & Defaye 2011ALEKSEEV, V. & DEFAYE, D. 2011. Taxonomic differentiation and world geographical distribution of the Eucyclops serrulatus group (Copepoda, Cyclopidae, Eucyclopinae). In Studies on Fresh-water Copepoda: a Volume in Honour of Bernard Dussart (D. Defaye, E. Suárez-Morales & C. Von Vaupel Klein, eds.). Crustaceana Monographs 16, E.J. Brill, Amsterdam, p.41-72.) (Figure 1C, D). The ornamentation of the antennal basis was not fully observable in the specimen available and is thus incomplete, but some of the main groups of spines were identified (Figure 1F); in general, their position and number of elements agrees with the data provided by Alekseev & Defaye (2011)ALEKSEEV, V. & DEFAYE, D. 2011. Taxonomic differentiation and world geographical distribution of the Eucyclops serrulatus group (Copepoda, Cyclopidae, Eucyclopinae). In Studies on Fresh-water Copepoda: a Volume in Honour of Bernard Dussart (D. Defaye, E. Suárez-Morales & C. Von Vaupel Klein, eds.). Crustaceana Monographs 16, E.J. Brill, Amsterdam, p.41-72. for E. neumani titicacae. The first swimming leg has 3-segmented endopod and exopod, the inner basipodal seta is strong, setulose and with spinules at its point of insertion (Figure 2A). The intercoxal sclerite has a medial row of small spinules (arrowed in Figure 2B). The second leg (Figure 2C) has also 3-segmented rami and the intercoxal sclerite has a single medial row of spinules (arrowed in Figure 1E). The third leg (Figure 3A) has 3-segmented rami and the intercoxal sclerite has two rows of spinules (II and III, following Alekseev & Defaye 2011ALEKSEEV, V. & DEFAYE, D. 2011. Taxonomic differentiation and world geographical distribution of the Eucyclops serrulatus group (Copepoda, Cyclopidae, Eucyclopinae). In Studies on Fresh-water Copepoda: a Volume in Honour of Bernard Dussart (D. Defaye, E. Suárez-Morales & C. Von Vaupel Klein, eds.). Crustaceana Monographs 16, E.J. Brill, Amsterdam, p.41-72.) on medial position (Figures 2E,F, 3B). The absence of distal row I is a difference of the Colombian specimens with respect to the type locality; in those specimens Alekseev & Defaye (2011)ALEKSEEV, V. & DEFAYE, D. 2011. Taxonomic differentiation and world geographical distribution of the Eucyclops serrulatus group (Copepoda, Cyclopidae, Eucyclopinae). In Studies on Fresh-water Copepoda: a Volume in Honour of Bernard Dussart (D. Defaye, E. Suárez-Morales & C. Von Vaupel Klein, eds.). Crustaceana Monographs 16, E.J. Brill, Amsterdam, p.41-72. reported the presence of row I with long hair-like elements. The fourth leg has also 3-segmented rami (Figure 3C), the third endopodal segment of leg 4 is about 1.66 longer that it is wide (Figure 3C); the proportion of this structure measured from the original description is 1.57 (Kiefer 1957KIEFER, F. 1957. Freilebende Ruderfüsskrebse (Crustacea Copepoda) des Titicaca sees. Veröff. Zool. Staatssamml. Muench. 4:125-150., fig. 13) and 1.55 from Ueno's report (Ueno 1966UENO, M. 1966. Zooplankton of Lake Titicaca on the Bolivian side. Hydrobiologia 29:547-568. http://dx.doi.org/10.1007/BF00189910
http://dx.doi.org/10.1007/BF00189910...
, fig. 71). The ornamentation of the intercoxal sclerite of the fourth swimming leg is represented by 3 rows of spinules (I-III) with longer elements along the distal margin (row I) (arrows in Figure 3D, Kiefer 1957KIEFER, F. 1957. Freilebende Ruderfüsskrebse (Crustacea Copepoda) des Titicaca sees. Veröff. Zool. Staatssamml. Muench. 4:125-150., fig. 13). In addition, the inner basipodal seta is uniserially setulated in the Colombian specimen (Figures 3D, 4A), a character also present in the specimens from Lake Titicaca (Kiefer 1957KIEFER, F. 1957. Freilebende Ruderfüsskrebse (Crustacea Copepoda) des Titicaca sees. Veröff. Zool. Staatssamml. Muench. 4:125-150., fig. 13). The ornamentation of the fourth leg coxopodite (Figure 4B, C) was evaluated following the nomenclature proposed by Alekseev & Defaye (2011)ALEKSEEV, V. & DEFAYE, D. 2011. Taxonomic differentiation and world geographical distribution of the Eucyclops serrulatus group (Copepoda, Cyclopidae, Eucyclopinae). In Studies on Fresh-water Copepoda: a Volume in Honour of Bernard Dussart (D. Defaye, E. Suárez-Morales & C. Von Vaupel Klein, eds.). Crustaceana Monographs 16, E.J. Brill, Amsterdam, p.41-72.; groups A, B, C+D, E, H, and I are present, thus agreeing with Alekseev & Defaye (2011)ALEKSEEV, V. & DEFAYE, D. 2011. Taxonomic differentiation and world geographical distribution of the Eucyclops serrulatus group (Copepoda, Cyclopidae, Eucyclopinae). In Studies on Fresh-water Copepoda: a Volume in Honour of Bernard Dussart (D. Defaye, E. Suárez-Morales & C. Von Vaupel Klein, eds.). Crustaceana Monographs 16, E.J. Brill, Amsterdam, p.41-72. observations from the type specimens. The fifth leg inner spine is shorter than the two adjacent setae (Figures 4D, E, Kiefer 1957KIEFER, F. 1957. Freilebende Ruderfüsskrebse (Crustacea Copepoda) des Titicaca sees. Veröff. Zool. Staatssamml. Muench. 4:125-150., fig. 14, Ueno 1966UENO, M. 1966. Zooplankton of Lake Titicaca on the Bolivian side. Hydrobiologia 29:547-568. http://dx.doi.org/10.1007/BF00189910
http://dx.doi.org/10.1007/BF00189910...
, fig. 70). In the Colombian specimen the spinules on the outer margin of the caudal rami are restricted to a row of 4-6 spinules inserted on a reduced area close to the insertion of the outer seta. The row of spinules does not reach half the length of outer margin (Figure 4F, Kiefer 1957KIEFER, F. 1957. Freilebende Ruderfüsskrebse (Crustacea Copepoda) des Titicaca sees. Veröff. Zool. Staatssamml. Muench. 4:125-150., fig. 11, Ueno 1966UENO, M. 1966. Zooplankton of Lake Titicaca on the Bolivian side. Hydrobiologia 29:547-568. http://dx.doi.org/10.1007/BF00189910
http://dx.doi.org/10.1007/BF00189910...
, fig. 70). The length/width proportion of the caudal ramus in the Colombian specimen (6.0) (Figure 4F) is within the range known in the Titicaca specimens, varying between 5.7 and 6.4 (Kiefer 1957KIEFER, F. 1957. Freilebende Ruderfüsskrebse (Crustacea Copepoda) des Titicaca sees. Veröff. Zool. Staatssamml. Muench. 4:125-150., Ueno 1966UENO, M. 1966. Zooplankton of Lake Titicaca on the Bolivian side. Hydrobiologia 29:547-568. http://dx.doi.org/10.1007/BF00189910
http://dx.doi.org/10.1007/BF00189910...
, Reid 1985REID, J.W. 1985. Chave de identificação e lista de referencias para as espécies continentais sulamericanas de vida livre da ordem Cyclopoida (Crustacea, Copepoda). Bolm. Zool., Univ. São Paulo 9:17-143.). In our specimen the length ratio dorsal caudal seta/caudal ramus length is 0.4; this ratio is 0.3 in the Titicaca specimens (Kiefer 1957KIEFER, F. 1957. Freilebende Ruderfüsskrebse (Crustacea Copepoda) des Titicaca sees. Veröff. Zool. Staatssamml. Muench. 4:125-150.).

Figure 2.
Eucyclops neumani titicacae from La Guajira, Colombia. Adult female. A. leg 1. B. intercoxal sclerite of leg 1. C. leg 2. D. intercoxal sclerite of leg 2. Intercoxal sclerite of leg 3 (E) showing two rows (II, III) of setal elements, nomenclature follows Alekseev & Defaye (2011)ALEKSEEV, V. & DEFAYE, D. 2011. Taxonomic differentiation and world geographical distribution of the Eucyclops serrulatus group (Copepoda, Cyclopidae, Eucyclopinae). In Studies on Fresh-water Copepoda: a Volume in Honour of Bernard Dussart (D. Defaye, E. Suárez-Morales & C. Von Vaupel Klein, eds.). Crustaceana Monographs 16, E.J. Brill, Amsterdam, p.41-72.; F. same, with position of both rows (arrowed).

Figure 3.
Eucyclops neumani titicacae from La Guajira, Colombia. Adult female. A. leg 3. B. intercoxal sclerite of leg 3; C. leg 4; D. intercoxal sclerite of leg 4 showing three rows (I-III) of setal elements, nomenclature follows Alekseev & Defaye (2011)ALEKSEEV, V. & DEFAYE, D. 2011. Taxonomic differentiation and world geographical distribution of the Eucyclops serrulatus group (Copepoda, Cyclopidae, Eucyclopinae). In Studies on Fresh-water Copepoda: a Volume in Honour of Bernard Dussart (D. Defaye, E. Suárez-Morales & C. Von Vaupel Klein, eds.). Crustaceana Monographs 16, E.J. Brill, Amsterdam, p.41-72..

Figure 4.
Eucyclops neumani titicacae from La Guajira, Colombia. Adult female. A. leg 4, intercoxal sclerite of another specimen showing ornamentation and gap of inner coxal seta (arrowed); B. coxopodite of leg 4; C. coxopodite of leg 4 showing ornamentation following nomenclature by Alekseev & Defaye (2011)ALEKSEEV, V. & DEFAYE, D. 2011. Taxonomic differentiation and world geographical distribution of the Eucyclops serrulatus group (Copepoda, Cyclopidae, Eucyclopinae). In Studies on Fresh-water Copepoda: a Volume in Honour of Bernard Dussart (D. Defaye, E. Suárez-Morales & C. Von Vaupel Klein, eds.). Crustaceana Monographs 16, E.J. Brill, Amsterdam, p.41-72.; D. fifth leg; E. fifth leg of another specimen showing spiniform seta shorter than adjacent terminal setae; F. caudal rami showing reduced saw (arrowed, with only 4-6 elements) on outer margin.

This species closely resembles its congener E. neumani, also a Neotropical species (Pesta 1927PESTA, O. 1927. Ein Beitrag zur Kenntnis der Copepodenfauna von Argentinien. Zool. Anz. 73(3-4):67-80., Reid 1985REID, J.W. 1985. Chave de identificação e lista de referencias para as espécies continentais sulamericanas de vida livre da ordem Cyclopoida (Crustacea, Copepoda). Bolm. Zool., Univ. São Paulo 9:17-143., Dussart & Frutos 1986DUSSART, B.H. & FRUTOS, S.M. 1986. Sur quelques Copépodes d'Argentine 2. Copépodes du Paraná Medio. Rev. Hydrobiol. Trop. 19(3-d): 241-262.) and both can be easily confused. Ueno (1966)UENO, M. 1966. Zooplankton of Lake Titicaca on the Bolivian side. Hydrobiologia 29:547-568. http://dx.doi.org/10.1007/BF00189910
http://dx.doi.org/10.1007/BF00189910...
reported it as E. neumani from the Bolivian side of Lake Titicaca; it is probable that he was not aware of Kiefer's description of N. neumani titicacae. These two subspecies can be distinguished by several subtle characters including: 1) the consistently shorter saw of the caudal rami in E. n. titicacae, mainly restricted to a few spinules (4-6) adjacent to the insertion point of the outer lateral seta (Ueno 1966UENO, M. 1966. Zooplankton of Lake Titicaca on the Bolivian side. Hydrobiologia 29:547-568. http://dx.doi.org/10.1007/BF00189910
http://dx.doi.org/10.1007/BF00189910...
, fig. 70). In E. n. neumani the saw is clearly longer, with more spines (+15), and it reaches half the length of the ramus (Reid 1985REID, J.W. 1985. Chave de identificação e lista de referencias para as espécies continentais sulamericanas de vida livre da ordem Cyclopoida (Crustacea, Copepoda). Bolm. Zool., Univ. São Paulo 9:17-143., Dussart & Frutos 1986DUSSART, B.H. & FRUTOS, S.M. 1986. Sur quelques Copépodes d'Argentine 2. Copépodes du Paraná Medio. Rev. Hydrobiol. Trop. 19(3-d): 241-262., fig. 33); 2) the length/width ratio of the third endopodal segment of the fourth leg is 1.5-1.6 in E. n. titicacae (Ueno, 1966UENO, M. 1966. Zooplankton of Lake Titicaca on the Bolivian side. Hydrobiologia 29:547-568. http://dx.doi.org/10.1007/BF00189910
http://dx.doi.org/10.1007/BF00189910...
, fig. 71) and 1.8 in E. n. neumani (Dussart & Frutos 1986DUSSART, B.H. & FRUTOS, S.M. 1986. Sur quelques Copépodes d'Argentine 2. Copépodes du Paraná Medio. Rev. Hydrobiol. Trop. 19(3-d): 241-262., fig. 35); 3) the length of the fifth leg spiniform setal element is shorter than the other two setae in E. n. titicacae (Kiefer 1957KIEFER, F. 1957. Freilebende Ruderfüsskrebse (Crustacea Copepoda) des Titicaca sees. Veröff. Zool. Staatssamml. Muench. 4:125-150., Ueno 1966UENO, M. 1966. Zooplankton of Lake Titicaca on the Bolivian side. Hydrobiologia 29:547-568. http://dx.doi.org/10.1007/BF00189910
http://dx.doi.org/10.1007/BF00189910...
) whereas the three elements are equally long in E. n. neumani (Dussart & Frutos 1986DUSSART, B.H. & FRUTOS, S.M. 1986. Sur quelques Copépodes d'Argentine 2. Copépodes du Paraná Medio. Rev. Hydrobiol. Trop. 19(3-d): 241-262., fig. 34). An additional character is the length ratio of the dorsal seta/caudal ramus length, the figure is 0.22 in E. n. neumani (Dussart & Frutos 1986DUSSART, B.H. & FRUTOS, S.M. 1986. Sur quelques Copépodes d'Argentine 2. Copépodes du Paraná Medio. Rev. Hydrobiol. Trop. 19(3-d): 241-262.) and 0.30–0.45 in E. neumani titicacae. Overall, it is confirmed that the morphological differences between these two taxa are consistent and are probably related to separate species.

1.

Distribution

According to the biogeographic analysis by Mercado-Salas et al. (2012)MERCADO-SALAS, N., POZO, C., MORRONE, J. & SUÁREZ-MORALES, E. 2012. Distribution patterns of the American species of the freshwater genus Eucyclops (Copepoda: Cyclopoida). J. Crust. Biol. 32:457-464. http://dx.doi.org/10.1163/193724012X626502
http://dx.doi.org/10.1163/193724012X6265...
, the track of E. n. titicacae runs from Lake Titicaca-Peru to Lake Valencia-Venezuela. The latter water body is relatively near the new locality in Colombia. Hence, this finding is consistent with the Western Amazonian (WA) biogeographic track defined for this subspecies (Mercado-Salas et al. 2012MERCADO-SALAS, N., POZO, C., MORRONE, J. & SUÁREZ-MORALES, E. 2012. Distribution patterns of the American species of the freshwater genus Eucyclops (Copepoda: Cyclopoida). J. Crust. Biol. 32:457-464. http://dx.doi.org/10.1163/193724012X626502
http://dx.doi.org/10.1163/193724012X6265...
) and expands this track toward the northern Colombian coast. This WA track also connects two important Neotropical basins, the Amazon and the Orinoco; a recent survey provides evidence showing active gene flow and dispersal between these two large basins through the Casiquiare corridor (Willis et al. 2010WILLIS, S.C., NUNES, M., MONTAÑA, C., FARIAS, I.P., ORTIZ, G. & LOVEJOY, N.R. 2010. The Casiquiare river acts as a corridor between the Amazonas and Orinoco river basins: biogeographic analysis of the genus Cichla. Mol. Ecol. 19:2014-1030. PMid:20149086. http://dx.doi.org/10.1111/j.1365-294X.2010.04540.x
http://dx.doi.org/10.1111/j.1365-294X.20...
). The southern limits of the large Amazonian subregion are determined by the historical separation of the Paraguay and Paraná rivers from the Amazonas basin. This biogeographic province, the Chacoan subregion (Urtubey et al. 2010URTUBEY, E., STUESSY, T.F., TREMETSBERGER, K. & MORRONE, J.J. 2010. The South American biogeographic transition zone: an analysis from Asteraceae. Taxon 59:505-509.) is independent from that related to the known distributional pattern of E. n. neumani, a species known from Argentina, Paraguay, Uruguay, and central and southern Brazil (Reid 1985REID, J.W. 1985. Chave de identificação e lista de referencias para as espécies continentais sulamericanas de vida livre da ordem Cyclopoida (Crustacea, Copepoda). Bolm. Zool., Univ. São Paulo 9:17-143., Mercado-Salas et al. 2012MERCADO-SALAS, N., POZO, C., MORRONE, J. & SUÁREZ-MORALES, E. 2012. Distribution patterns of the American species of the freshwater genus Eucyclops (Copepoda: Cyclopoida). J. Crust. Biol. 32:457-464. http://dx.doi.org/10.1163/193724012X626502
http://dx.doi.org/10.1163/193724012X6265...
). This is an additional evidence to support the notion that these subspecies are likely to represent independent species, E. neumani (Pesta, 1927PESTA, O. 1927. Ein Beitrag zur Kenntnis der Copepodenfauna von Argentinien. Zool. Anz. 73(3-4):67-80.), and E. titicacaeKiefer, 1957KIEFER, F. 1957. Freilebende Ruderfüsskrebse (Crustacea Copepoda) des Titicaca sees. Veröff. Zool. Staatssamml. Muench. 4:125-150..

The present record expands the occurrence of the former subspecies E. neumani titicacae (as E. titicacae) to Colombia, and it is now known to occur in three sites of South America (Figure 5). In addition, these localities represent also a remarkable range of altitude for this species: 3805m (Lake Titicaca), 407 m (Lake Valencia), and 0 m (Navío Quebrado Lagoon). Considering this new record, the number of species of Eucyclops known for the Colombian copepod fauna (Gaviria & Aranguren 2007GAVIRIA, S. & ARANGUREN, N. 2007. Especies de vida libre de la subclase Copepoda (Arthropoda, Crustacea) en aguas continentales de Colombia. Biota Colomb. 8:53-68.) increased to 8.

Figure 5.
Map showing records of Eucyclops titicacaeKiefer, 1957KIEFER, F. 1957. Freilebende Ruderfüsskrebse (Crustacea Copepoda) des Titicaca sees. Veröff. Zool. Staatssamml. Muench. 4:125-150., a species known from three localities in South America.

Additional characters can be found in Reid (1985)REID, J.W. 1985. Chave de identificação e lista de referencias para as espécies continentais sulamericanas de vida livre da ordem Cyclopoida (Crustacea, Copepoda). Bolm. Zool., Univ. São Paulo 9:17-143., Suárez-Morales (2004)SUÁREZ-MORALES, E. 2004. A new species of Eucyclops (Copepoda: Cyclopoida) from Southeast Mexico with a key for the identification of the species recorded in Mexico. Zootaxa 617:1-18. and Alekseev et al. (2006)ALEKSEEV, V.R., DUMONT, H.J., PENSAERT, J., BARIBWEGURE, D. & VANFLETEREN, J.R. 2006. A redescription of Eucyclops serrulatus (Fischer, 1851) (Crustacea: Copepoda: Cyclopoida) and some related taxa, with a phylogeny of the E. serrulatus group. Zool. Scr. 35:123-147. http://dx.doi.org/10.1111/j.1463-6409.2006.00223.x
http://dx.doi.org/10.1111/j.1463-6409.20...
.


References

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  • WILLIS, S.C., NUNES, M., MONTAÑA, C., FARIAS, I.P., ORTIZ, G. & LOVEJOY, N.R. 2010. The Casiquiare river acts as a corridor between the Amazonas and Orinoco river basins: biogeographic analysis of the genus Cichla. Mol. Ecol. 19:2014-1030. PMid:20149086. http://dx.doi.org/10.1111/j.1365-294X.2010.04540.x
    » http://dx.doi.org/10.1111/j.1365-294X.2010.04540.x

Publication Dates

  • Publication in this collection
    Dec 2013

History

  • Received
    19 June 2013
  • Reviewed
    23 Oct 2013
  • Accepted
    4 Nov 2013
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