Maxillopoda: Copepoda: Calanoida, Cyclopoida

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Diversity of freshwater copepods (Maxillopoda: Copepoda: Calanoida, Cyclopoida) from Chiapas, Mexico with a description of Mastigodiaptomus suarezmoralesi sp. nov a

M. A. Gutiérrez-Aguirre & A. Cervantes-Martínez

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Unidad Cozumel, Universidad de Quintana Roo (UQROO), Cozumel, Quintana Roo, 77600, Mexico Version of record first published: 21 Feb 2013. To cite this article: M. A. Gutiérrez-Aguirre & A. Cervantes-Martínez (2013): Diversity of freshwater copepods (Maxillopoda: Copepoda: Calanoida, Cyclopoida) from Chiapas, Mexico with a description of Mastigodiaptomus suarezmoralesi sp. nov, Journal of Natural History, DOI:10.1080/00222933.2012.742587 To link to this article: http://dx.doi.org/10.1080/00222933.2012.742587

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Journal of Natural History, 2013 http://dx.doi.org/10.1080/00222933.2012.742587

Diversity of freshwater copepods (Maxillopoda: Copepoda: Calanoida, Cyclopoida) from Chiapas, Mexico with a description of Mastigodiaptomus suarezmoralesi sp. nov. M.A. Gutiérrez-Aguirre* and A. Cervantes-Martínez Unidad Cozumel, Universidad de Quintana Roo (UQROO), Cozumel, Quintana Roo 77600. Mexico

Downloaded by [201.116.0.180] at 17:15 07 March 2013

(Received 9 October 2011; final version received 8 October 2012)

In Mexico the knowledge of the freshwater copepod fauna is largely incomplete; after a field expedition to survey the Calanoida and Cyclopoida richness in Chiapas (southeastern Mexico), three species increase the full inventory in the country (of around 86 species). In this manuscript the first record of the genus Metacyclops in Mexico and a new record of Acanthocyclops einslei are reported. In addition, a full description of specimens of a new species assignable to the genus Mastigodiaptomus (M. suarezmoralesi sp. nov.) is presented. This research provides a full morphological description of adult males and females of the new species as well as comments on the morphology of Aglaodiaptomus clavipes. The new records were compared with previous taxonomic reports. Detailed analysis and illustration of the copepod morphology have been performed with the aid of camera lucida, light microscopy and scanning electron microscopy. Most of the species recorded show Neotropical affinity. http://www.zoobank.org/urn:lsid:zoobank.org:pub:4E3C5C42-F73E-4D91-A85FE5794B146734 Keywords: Copepoda; free-living; inventory; Nearctic; Neotropical

Introduction In Mexico the free-living freshwater Copepoda are relatively well known only in isolated regions such as the Yucatan Peninsula (in part) (Suárez-Morales and Reid 2003), the central portion of the country (Dodson and Silva-Briano 1996), and the arid and semiarid areas of northern Mexico (in part) (Zamudio-Valdéz 1991; Suárez-Morales et al. 2010), but there are extensive regions without basic inventories in this tropical, biologically diverse country. Hence the diversity and distribution of copepods in the continental waters of Mexico are poorly known (Suárez-Morales and Reid 1998; Gutiérrez-Aguirre and Suárez-Morales 2001). This study provides information about the richness of the copepod fauna in ponds and lakes of Chiapas State, southeastern Mexico, whose copepod fauna is almost completely un-investigated: previous papers report only five species of the genus Eucyclops Claus 1893 or Mesosyclops G. O. Sars 1912 in the area (see Suárez-Morales 2004; Suárez-Morales et al. 2005; GutiérrezAguirre et al. 2006). This region comprises different hydrological basins and a wide variety of aquatic habitats, therefore deserving further taxonomic research to establish their basic copepod inventory. The goal of this study is to perform a general analysis of *Corresponding author. Email: [email protected] © 2013 Taylor & Francis

2 M.A. Gutiérrez-Aguirre and A. Cervantes-Martínez taxonomic composition and biogeographic affinities of 13 freshwater Calanoida and Cyclopoida, including one species new to science, two new records for the country, and one range extension.

Material and methods


Samples of plankton from limnetic and littoral habitats from natural lakes, ephemeral or permanent ponds, and reservoirs were obtained from freshwater habitats from the high mountain region of Chiapas during 2000; Figure 1 shows the sampled localities in the surveyed area, which is above 1500 m. Samples were obtained using a standard plankton net with a 0.05-mm mesh, by performing near-shore and limnetic plankton trawls. The biological material was fixed and preserved in 70% ethanol, and then

Figure 1. Sampling localities in Chiapas, Mexico. Marks represent the area where the new records, range extension and new species were collected. Square = Acanthocyclops einslei; circle = Metacyclops cushae; asterisk = Aglaodiaptomus clavipes and Mastigodiaptomus suarezmoralesi.

Journal of Natural History 3


processed for identification following techniques described by Reid (2003). All adult Calanoida and Cyclopoida in the samples were identified to species level. The specimens were dissected with tungsten needles and appendages were mounted in glycerine for taxonomic analysis. The mouth parts, swimming legs and other taxonomically important structures were illustrated with the aid of a camera lucida. Some specimens were prepared for scanning electron microscopy (SEM) to allow the detailed observation of some structures, using a JEOL LV-5900 microscope at El Colegio de la Frontera Sur (ECOSUR) in Tapachula, Chiapas. Specimens were deposited in the Collection of Zooplankton of ECOSUR, Chetumal, Mexico (ECO-CHZ), and the Colección Nacional de Crustáceos (CNCR) del Instituto de Biología, Universidad Nacional Autónoma de México. Abbreviations used in the descriptive section are as follows: P1–P4, first to fourth swimming legs; Exp, exopod; Enp, endopod; s, seta(e); ae, aesthetasc; sp, spine; sps, spiniform process; Fu, furcal rami.

Results A total of 13 species of Copepoda were recorded from samples obtained during this survey. The inventory includes three Calanoida (Diaptomidae) and 10 Cyclopoida (Eucyclopinae, Cyclopinae) (Table 1). Taxonomic arrangement and nomenclature follows Dussart and Defaye (1995). Comments on morphology and biogeographic Table 1. Inventory of free-living copepods (Crustacea: Calanoida, Cyclopoida) recorded in freshwater habitats of Chiapas. Taxon Order Calanoida Family Diaptomidae Subfamily Diaptominae Aglaodiaptomus clavipes (Schacht, 1897) (N) Arctodiaptomus dorsalis (Marsh, 1907) (Nt) Mastigodiaptomus suarezmoralesi sp. nov. Order Cyclopoida Family Cyclopidae Subfamily Eucyclopinae Eucyclops bondi Kiefer, 1934 (Nt) E. prionophorus Kiefer, 1931 (Nt) E. pectinifer (Crangin, 1883) (N) Macrocyclops albidus albidus (Jurine, 1820) (C) Tropocyclops prasinus aztequei Lindberg, 1955 (Nt) Subfamily Cyclopinae Acanthocyclops einslei Mirabdullayev & Defaye, 2004 (Pa, N) Microcyclops ceibaensis (Marsh, 1919) (Nt) Mesocycplos brasilianus Kiefer, 1933 (Nt) Metacyclops cushae Reid, 1991 (N) Thermocyclops inversus Kiefer, 1936 (Nt) N, nearctic forms; Nt, neotropical forms; C, cosmopolitan forms; Pa, Palaearctic forms.


4 M.A. Gutiérrez-Aguirre and A. Cervantes-Martínez analysis are added for the new records and range extensions for Mexico. We report the occurrence of the Nearctic Aglaodiaptomus clavipes with a taxonomic examination using light and scanning microscopy to provide a full morphological description of both the adult males and females of the Chiapas material and compare them with previous taxonomic reports of the species from other geographical regions. One species new to science (assignable to the genus Mastigodiaptomus) is described herein. The Neotropical Mastigodiaptomus (Suárez-Morales 2003) is considered one of the most speciose genera in Mexico, where up to six of the eight known species have been recorded; Mastigodiaptomus albuquerquensis is the species with the widest distribution range in Mexico, whereas Mastigodiaptomus reidae and Mastigodiaptomus maya apparently are endemic to the south of the Yucatan Peninsula (Elías-Gutiérrez et al. 2008). The new species represents the seventh record of the genus in Mexico, and the ninth in the world. The order of the findings in the next section follows the recognized evolutionary relationship among species.

Systematics Aglaodiaptomus clavipes (Schacht, 1897) (Figures 2, 3)

Material examined One dissected, adult female from Laguna Cañada, Chiapas, Mexico (16◦ 06" 55"" N, 91◦ 40" 44"" W) collected 15.April.2000, slide sealed with Entellan (ECO-CHZ-05520). Six adult females and four adult males from Lago Tziscao, Chiapas, Mexico (16◦ 05" 19"" N, 91◦ 40" 10"" W) collected 15 April 2000, preserved in 70% ethanol with a drop of glycerine (ECO-CHZ-05521). Two adult females and two adult males used for SEM.

Description Female. Body measuring 1800–1950 µm excluding caudal setae, fifth pediger without dorsal process; urosomal length 23–24.3% of the body length (Figure 2A). Antennule 25-segmented, almost reaching end of prosome. Armament per segment as follows: 1s+1ae; 3s; 1s; 1s; 1s; 1s; 1s; 1s+1sp; 2s; 1s; 2s; 1s+1sp+1ae; 1s; 1s; 1s; 1s; 1s; 1s; 1s; 1s; 1s; 2s; 2s; 2s; 5s. Antennular segments 17, 19, 20 and 22 bearing one short, distally curved seta (Figure 2B). Metasomal wings not projected, urosome with genital double-somite 1.47–1.5 longer than wide, anal somite, and furcae which are hairy along medial margin, and bear a tiny spine close to insertion of lateral seta (arrowed in Figure 2C). Fifth leg with Enp shorter than Exp1; Enp unsegmented with two long, distal, feathered setae, which have more than half of the Enp length plus thin, distal spines (Figure 2D). Exp2 a curved claw; Exp 3 small but distinct (arrowed in Figure 2E). Genital somite with short spines laterally; genital field with strong convex plates projected ventrally (Figure 2F, G).



Figure 2. Aglaodiaptomus clavipes (Schacht, 1897). Female from Laguna Tziscao, Chiapas. (A) Habitus; (B) right antennule, segments 8–22; (C) urosome, dorsal; (D) Enp and Exp, fifth leg; (E) Exp2, and Exp3 (arrowed), fifth leg; (F) genital somite, ventral; (G) genital somite, lateral. Measures in photos are in µm. Scale bars 50 µm.

Male. Total body length excluding furcal setae 1750–1875 µm; urosome represents 26.6–28.5% of total body length (Figure 3A). Left fifth leg with two exopodal segments (left Exp1 arrowed in Figure 3B); distal segment cylindrical, with one short


6 M.A. Gutiérrez-Aguirre and A. Cervantes-Martínez

Figure 3. Aglaodiaptomus clavipes (Schacht, 1897). Male from Laguna Tziscao, Chiapas. (A) Habitus; (B) fifth leg, caudal (left Exp1 arrowed); (C) fifth leg, left Enp; (D) fifth leg, right Enp; (E) right antennule, segments 8–14; (F) right antennule, antepenultimate segment. Measurements in µm.

lamella and one long seta. Left End spiny, long, reaching the distal region of left Exp1 (Figure 3C). Right basis with three chitinous, triangular projections on posterior side (one basal and two medial), and one hook-like lamella as long as Exp1 (Figure 3B); right Exp1 quadrangular, Exp2 bearing one distal, short aculeus plus one terminal, long spine (Figure 3B). Right Enp shorter than Exp1, with a group of spines

Journal of Natural History 7 at tip (Figure 3D). Right antennule 22-segmented with armament per segment as follows: 1s+1ae; 3s; 1s; 1s; 1s; 1s; 1s; 1s+1sp; 1s+1ae; 1sps+1ae; 1sps+1ae; 2ae+1sp; 1sps+1ae; 2ae+1s; 2ae+1s; 1sps+1s+2ae; 1ae; 0; 1s; 2s; 2s; 5s+1ae (Figure 3E); antepenultimate antennular segment with a thin, hyaline membrane (Figure 3F).


Remarks Aglaodiaptomus clavipes is considered a Nearctic species (Suárez-Morales et al. 2010), with records in Mississippi, Alberta, Manitoba and northern Mexico. This is the southernmost record of the species. Specimens from Chiapas were assigned to A. clavipes because of the lack of projection in antepenultimate segment of right male A1, the presence of hyaline lamella in the same segment, and the ornamentation of the male P5. However, some morphological variations were found when Mexican specimens were compared with the illustrated analysis by Wilson and Yeatman (1959) with specimens from USA: the females surveyed here bear shorter antennules, and the spine close to the insertion of furcal lateral seta in the specimens from Chiapas is absent in the female illustrated by Wilson and Yeatman. On the other hand, the right EnpP5 in Mexican specimens is shorter than right Exp1P5 in males, in comparison with the sub-equal length in both structures in specimens from the USA. Mastigodiaptomus suarezmoralesi sp. nov. (Figures 4–7)

Material examined Holotype. Adult female collected 15 April 2000, from Laguna de Montebello 1, Chiapas, Mexico (16◦ 06" 42"" N, 91◦ 41" 32"" W), deposited at the Colección de Referencia de El Colegio de la Frontera Sur, registered under number ECO-CHZ-07545. Allotype. Adult male from Laguna de Montebello 1, Chiapas, Mexico, deposited at the Colección de Referencia de El Colegio de la Frontera Sur, registered under number ECO-Z-07546. Paratypes. Five adult males (CNCR 26675), and five adult females (CNCR 26676) from Laguna de Montebello 1, Chiapas, Mexico, preserved in 70% ethanol with a drop of glycerine, deposited at Colección Nacional de Crustáceos (CNCR) del Instituto de Biología, Universidad Nacional Autónoma de México. Eleven adult females and eight adult males from Laguna Tziscao, Chiapas, Mexico (16◦ 05" 19"" N, 91◦ 40" 10"" W) collected 15 April 2000, preserved in 70% ethanol with a drop of glycerine, deposited at the Colección de Referencia de El Colegio de la Frontera Sur, registered under number ECO-CHZ-05522. Ten adult females and ten adult males from Laguna Escondida, Chiapas, Mexico (16◦ 06" 43"" N, 91◦ 40" 36"" W) collected 15 April 2000, preserved in 70% ethanol with a drop of glycerine, registered under number ECO-CHZ-05523. Two adult females and two adult males used for SEM.

8 M.A. Gutiérrez-Aguirre and A. Cervantes-Martínez Type locality Laguna de Montebello 1, Chiapas, southeastern Mexico; 16◦ 06" 42"" N, 91◦ 41" 32"" W, 15. April. 2000, within Lagunas de Montebello National Park.


Description Female. Average length excluding caudal setae 1022.7 ± 26.8 µm; range 1000–1070 µm, n = 20. Prosome slightly wider at distal third, symmetrical in dorsal view (Figure 4A). In lateral view, the body is thin and arched downwards at level of second to fourth pediger, thin, without dorsal hump on fifth pediger (Figure 4B). Long, asymmetrical rostral points: right slightly longer than left (Figure 4C). Asymmetrical thoracic wings, left longer than right, both wings bearing two large spines directed posteriorly (Figure 4D,E). Three-segmented urosome; genital double somite asymmetrical: right margin slightly projected, bearing one large spine, left margin almost straight with one small spine; genital field bearing one upper convex plate over one semi-rectangular plate, and rounded protuberance on genital opening (Figures 4F, 7A); ventrally, surface of genital-double somite transversely striated distally (Figures 4F, 7B). Dorsal surface of genital-double somite striated with a right, pronounced wrinkle (Figure 4G). Anal somite subequal in length to preanal somite. Furcal rami hairy on medial and lateral margins; the four terminal, lateral and dorsal setae are subequal in length (Figure 4G), and all seta are biserially plumose. Antennule. Twenty-five-segmented (Figure 4H), tip reaching genital somite; armament per segment as follows: 1s+1ae; 3s+1ae; 1s+1ae; 1s; 1s+1ae; 1s; 1s+1ae; 1s+1sp; 2s+1ae; 1s; 2s; 1s+1sp+1ae; 1s; 1s+1ae; 1s; 1s+1ae; 1s; 1s; 1s+1ae; 1s; 1s; 1s+1ae; 1s+1ae; 2s; 3s+1ae. Antenna. Coxa with one long seta. Long basis with two subequal setae on inner, distal margin. Two-segmented Enp, proximal segment with two setae and one row of spines; Enp2 with two lobes: outer lobe with tiny spines plus four distal and two lateral setae; inner lobe with eight setae. Seven-segmented Exp; setation pattern on each segment as follows: 1, 3, 1, 1, 1, 1, 4 (Figure 5A). Mandible with six rounded teeth on gnathobase, a movable tooth at the tip, and a rounded lateral projection (Figure 5B). Coxa nude, basis with four setae. Bi-segmented Enp; Enp1 with four setae; Enp2 quadrangular, with tiny spines and eight distal, long setae. Four-segmented Exp, with 1, 1, 1, 3 setation pattern. Maxillule. Praecoxal arthrite with 13 spiniform setae, nine anterior and four posterior; coxal epipodite bearing nine long setae, inner two smaller and thinner than the others; coxal endite quadrangular with four setae on distal margin. Basis with one internal lobe bearing four setae. Similar number of setae on basal endite; one-segmented Enp with nine setae. One-segmented Exp with seven setae (Figure 5C). Maxilla. Praecoxa with two lobes, first lobe with four terminal and two lateral setae; second lobe bearing three long setae and tiny basal spines. Coxa with two lobes, each one with three long setae, distal lobe with spines along medial surface (Figure 5D). Two well-developed basal lobes; proximal lobe bearing four setae, distal lobe with one seta. Two-segmented Enp; Enp1 bearing one seta, Enp2 with four setae. Maxilliped. Praecoxa and coxa fused forming a long segment (Figure 5E). Coxa with three distinct lobes, first and second lobes each with three setae; third lobe with four setae plus two rows of long spine-like setae. Basis with a row of spine-like setae



Figure 4. Mastigodiaptomus suarezmoralesi sp. nov. Female from Laguna de Montebello 1, Chiapas. (A) Habitus, dorsal; (B) habitus, right side; (C) rostral points; (D) left thoracic wing; (E) right thoracic wing; (F) genital-double somite, ventral; (G) urosome, dorsal; (H) antennule. Scale bars 50 µm.



Figure 5. Mastigodiaptomus suarezmoralesi sp. nov. Female from Laguna de Montebello 1, Chiapas. (A) Antenna; (B) mandible; (C) maxillule, basal endite separated; (D) maxilla; (E) maxilliped; (F) P1; (G) P2; (H) P3; (I) P4; (J) fifth leg, Enp separated. Scale bars 50 µm.

plus three short setae. Six-segmented Enp; Enp1 partially fused to Enp2; setation pattern as 2, 3, 2, 2, 2, 4. Thoracic limbs. P1 with two-segmented Enp, and three-segmented Exp, coxa and basis with spine-like setae on lateral margins (Figure 5F). P2 to P4 with threesegmented Enps and Exps (Figure 5G–I), setation and spine formulae of each element of the thoracic limbs as in Table 2. Terminal exopodal spines of each P1–P4 with curved tips, armed with spines and hair-like setae (Figure 5F–I).

Journal of Natural History 11 Table 2. Setation formula for major armament of swimming legs (P1–P4) in the females and males of Mastigodiaptomus suarezmoralesi sp. nov. described here.

P1 P2 P3 P4

Coxa

Basis

Exopod

Endopod

0-1 0-1 0-1 0-1

0-0 0-0 0-0 0-0

I-1; 0-1; I-3-2 I-1: I-1; I-3-3 I-1; I-1; I-3-3 I-1; I-1; I-3-3

0-1; 1-2-3 0-1; 0-2; 2-2-3 0-1; 0-2; 2-2-3 0-1; 0-2; 2-2-3


Roman numerals indicate spines, arabic numbers are setae.

Fifth leg. Coxa with one large sensilla on posterior view, basis with a delicate lateral seta (Figure 5J). Three-segmented Exp: Exp1 cylindrical, Exp2 is a biserially armed claw, and Exp3 distinct, bearing a long seta and a short spine (Figure 5J). Bisegmented Enp as long as Exp1, terminal Enp segment with two long setae plus one oblique row of hair-like setae, proximal segment nude (Figure 5J). Male. Total body length 960.9 ± 27.73 µm on average, range 910–1000 µm, n = 15. Slender body, cephalosome is the widest prosomal region in dorsal view. Suture between fourth and fifth pediger dorsally incomplete (Figure 6A). As in female, the body is arched downwards in lateral view (Figure 6B). Long rostral points, the left is slightly shorter than the right, which is bearing a lateral, basal hump (Figure 6C). Left antennule as in female. Left thoracic wing not projected, bearing one spine (Figure 6D); right thoracic wing projected, with one large ventral spine, plus one thin dorsal seta (arrowed in Figure 6E). Right side of first urosomal segment with one spine (Figure 6E). Five-segmented urosome; rows of tiny spines on dorsal surface of second to fourth urosomal segments (Figure 6F); asymmetrical preanal segment, longer and bulbose in right side. Furcal rami hairy on medial margin. Right antennule. Twenty-two-segmented; armament per segment as follows: 1s+1ae; 2s+2ae; 1s+1ae; 1s; 1s+1ae; 1s; 1s+1ae; 1s+1sp; 2s+1ae; 1s+1sps; 1s+1sps; 1s+1ae+1sp; 1s+1ae+1sps; 2s+1ae+1sps; 2s+1ae+1sps; 2s+1ae+1sps; 1s; 1s; 1s+2ae; 4s; 2s; 4s+1ae (Figure 6G). Antepenultimate segment with a fang-like projection, less than half the length of penultimate antennular segment, and grooves on inner surface (Figure 7C). Segments 13–16 wider. Spiniform process on segment 10 shorter than the bearing segment, reaching the base of the stout spine of the next segment. Spiniform process on segment 11, 2.1 times longer than spiniform process on segment 10. Segments 8 and 12 with one short spine. Parallel spiniform processes on segments 13 and 14. Base of stout spine on segment 13, thinner than the length of the bearing segment. Short spiniform processes on segment 15 and 16 (Figure 6H). Mouth parts, and P1–P4 as in females. Fifth leg, caudal side. Long distal sensillae on both, left and right coxae (Figure 6I). Right basis with two projections on inner side: one medial semi-elliptical lamella, and one triangular, basal process, plus one fold along medial axis (Figures 6I, 7D). Right Enp twice as long as Exp1, which bears a chitinous membrane at its posterior edge. Exp2 1.8–1.9 times longer than wide with two curved, short hyaline membranes; aculeus inserted at distal third of the posterior side of the segment.



Figure 6. Mastigodiaptomus suarezmoralesi sp. nov., male from Laguna de Montebello 1, Chiapas, (A) Habitus, dorsal; (B) habitus, right side; (C) rostral points; (D) left thoracic wing; (E) right thoracic wing (dorsal seta arrowed); (F) urosome, dorsal; (G) right antennule, last three segments separated; (H) right antennule, segments 8–16; (I) fifth leg caudal, Enps and left Exp2 separated. Scale bars 50 µm.



Figure 7. Mastigodiaptomus suarezmoralesi sp. nov. (A, B) Female, (A) genital field; (B) genitaldouble somite, ventral. (C–F) Male, (C) right antennule, antepenultimate segment; (D) right basis, fifth leg; (E) aculeus; (F) terminal spine of right Exp2. Measurements in µm.

Exp2 is 1.65–1.74 times longer than aculeus; which is armed with spines on medial edge (Figure 7E) and with a curved, sharp tip; terminal claw very long, bent, with looped sharp tip (Figure 7F). Right Enp unsegmented bearing two long setae and one oblique row of tiny spines. Left leg with quadrangular basis and bi-segmented Enp. Left Enp with two spines plus one row of setae on its tip (Figure 6I). Bi-segmented Exp; Exp1 is

14 M.A. Gutiérrez-Aguirre and A. Cervantes-Martínez 2.0–2.1 times longer than Exp2; which bears a lateral spiniform seta. Exp2 tapering distally and with two or three short chitinous denticles (Figure 6I).

Etymology


The species is named after Eduardo Suárez-Morales, in recognition for his extensive contribution to the knowledge of the marine and freshwater copepods of Mexico and the world.

Remarks The specimens examined here, were included under the genus Mastigodiaptomus Light, 1939 because of the possession of the following morphological features (1) segment 11 of both female antennules and left male antennule with two setae; (2) coxa of female P5 with a long, spatulated sensilla; (3) one lateral spine on Exp1P1 in both sexes; (4) Enp of right male P5 longer than right Exp1; (5) right male antennule with spiniform process on segments 10, 11 and 13–16; (6) basis of right male P5 with hyaline lamellae on caudal side. Mastigodiaptomus suarezmoralesi sp. nov. does not match any species in the key by Wilson and Yeatman (1959) or in the key by Suárez-Morales and ElíasGutiérrez (2000). The new species can be distinguished from other known species of Mastigodiaptomus by the combination of several unique characters such as the wrinkled and striated genital-double somite in females, or the tiny spines on the dorsal surface of urosomal somites in males. The ornamentation of the right basis and Exp2, and the looped tips of the aculeus and terminal claw of the fifth leg in males, or the curved tips in terminal spines of all P1–P4, and the long rostral points in females and males are also relevant diagnostic characters in the new species. Other morphological differences were found when M. suarezmoralesi sp. nov. was compared with the eight known Mastigodiaptomus species, especially in the female urosome and male fifth leg. The morphological comparison is on Table 3. The dorsal process on the last thoracic segment was absent in all the adult females surveyed here; this character has been recorded as variable in or between populations of M. amatitlanensis (Wilson and Yeatman 1959); M. texensis (Wilson 1953); M. albuquerquensis (Bowman 1986); and M. montezumae (Santos-Silva et al. 1996). Mastigodiaptomus reidae is another species without this process (Suárez-Morales and Elías-Gutiérrez 2000). According to Wilson and Yeatman (1959), in M. purpureus the dorsal projection on the fifth female pediger is always present. Acanthocyclops einslei Mirabdullayev and Defaye, 2004

Material examined Four adult males and one female urosome from km 16 pond, San Cristóbal-Palenque highway, Chiapas, Mexico (16◦ 42" 59"" N, 92◦ 40" 43"" W) collected 13 January 2001, preserved in 70% ethanol with a drop of glycerine (ECO-CHZ-05524).

M. albuquerquensis (Bowman 1986; Dussart and Defaye 1995)

M. purpureus (Wilson and Yeatman 1959)

1.9 Reduced

Bisegmented 1.57

1.12–1.2 Reduced

Bisegmented 2.0–2.1

Unsegmented 2.33–2.5

1.38 Reduced

Unsegmented 2.0

1.62 Strongly developed

Unsegmented 1.6

2.0 Absent

1.08

Unsegmented 2.5–3.0

1.11 Reduced

1.65

Unsegmented 1.12

2.18 Reduced

1.14

Unsegmented 1.75

2.14 Reduced

1.0

(Continued)

Unsegmented 1.85

1.17 Absent

1.53

Both margins Both margins Almost parallel laterally laterally produced, produced, nearly symmetrical symmetrical

M. amatitlanensis (Wilson and Yeatman 1959)

1.16–1.28

genital-double somite ♀, P5 L Exp1/Enp ♂, Right A1, spinal process on segment 16 ♂, P5 left Enp ♂, Left P5, L Exp1/Exp2

Almost parallel

M. texensis (Wilson 1953)

♀, L/W,

L/W, rostral points ♀, Lateral margins Left margin almost of straight; right genital-double margin somite produced

margin

Both margins laterally produced, asymmetrical

M. montezumae M. reidae M. maya (Suárez-Morales (Santos-Silva (Suárezet al. 1996) and Morales and Elías-Gutiérrez Elías-Gutiérrez 2000) 2000)

Almost parallel Left margin Left margin slightly slightly produced; produced; right margin right margin almost produced straight 1.2 1.75 2.0

M. nesus (Bowman 1986)

On medial and On medial and On medial and On medial On medial and On medial and On medial and On medial and On medial margin lateral lateral lateral margin lateral lateral lateral margins lateral margins margins margins margins margins margins 5.33 (♀); 4.66 (♂) ND 2.0 (♀); 1.4 (♂) 3.0 (♀); 2.33 (♂) 2.0 (♀); 2.25 (♂) ND ND ND ND

M. suarezmoralesi sp. nov.

♀, Hairs on Fu

Character

Table 3. Comparison (based on published data) of nine species of Mastigodiaptomus.



2 short 1 long, quadsemi-circular rangular lamellae on hyaline medial lamella margin

♂, P5, right 1 low, rounded protuberance proximally

1 basal rounded protrusion

M. maya (SuárezMorales and Elías-Gutiérrez 2000)

M. montezumae (Santos-Silva et al. 1996)

1 chitinous semi-circular process on proximal third 2 semi-circular lamellae, and a longitudinal “Y”-shaped ridge

1 basal, large 1 basal lobular subrectangular projection protrusion, 1 basal, bulb-like process, and 1 semi-circular process on medial margin

M. reidae (Suárez-Morales and Elías-Gutiérrez 2000)

ND, not determined; Fu, furcal rami; L/W, length/width ratio; L, length ratio.

Exp2 armament

1 semi-circular lamella on medial margin

1 semielliptical lamella on medial margin, plus 1 basal triangular process, and 1 fold

armament

♂, P5 right basis

M. nesus (Bowman 1986)

M. suarezmoralesi sp. nov.

Character

Table 3. (Continued).

1 protrusion with a crescentshaped lamella, and one distally directed lamella on medial margin 1 semi-circular lamella

M. texensis (Wilson 1953)


1 straight lamella

1 distal cuneiform lamella

M. amatitlanensis (Wilson and Yeatman 1959)

M. purpureus (Wilson and Yeatman 1959)

1 long curved hyaline lamella

2 short semi-circular lamellae: 1 medial and 1 lateral

1 hyaline distal 1 semi-circular lamella on lamella, and medial 1 semimargin circular lamella on medial margin

M. albuquerquensis (Bowman 1986; Dussart and Defaye 1995)


Journal of Natural History 17 Remarks This is a new record for Mexico; Acanthocyclops einslei was recently described from biological material collected in Europe, Japan, USA and Canada (Mirabdullayev and Defaye 2004) the species belongs to the Acanthocyclops robustus species-complex. All morphological characters, even the meristic features observed in the specimens from Chiapas, are similar to those of the original description, except the presence of denticules (arranged in arched rows) on ventral and dorsal surfaces of anal somite found in the Chiapas material. Metacyclops cushae Reid, 1991


Material examined Ten adult females, and one adult male from Nuevo San Juan Chamula pond, Chiapas, Mexico (16◦ 06" 50"" N, 91◦ 27" 11"" W) collected 16 April 2000, preserved in 70% ethanol with a drop of glycerine (ECO-CHZ-05525).

Remarks The knowledge of the genus Metacyclops in the Nearctic region is limited, the genus is considered as tropical and temperate, with around 52 species and subspecies worldwide; currently up to 26 species of Metacyclops have been recorded in the Americas (Reid 1991), but only Metacyclops cushae, Metacyclops gracilis Lilljeborg 1853, and Metacyclops cf. campestris have been confirmed as valid records in the Nearctic region (Mercado-Salas 2009). Metacyclops cushae was described upon specimens from southeastern USA (Louisiana), hence this record extends the distributional pattern of the species, and confirms that the number of Cyclopinae genera recognized in Mexico has increased to 10 (see Elías-Gutiérrez et al. 2008) including the record of Metacyclops cf. campestris in Coahuila, México (Mercado-Salas 2009).

Discussion Aglaodiaptomus clavipes is a species recorded in a wide range of habitats, occurring in great lakes, permanent and ephemeral ponds or even in rivers (Torke 2001); with records in Rocky Mountains, east Wisconsin, Alberta, Manitoba and southwards to Oklahoma, Arizona and Mexico, this species is mainly a Nearctic copepod. Its southernmost confirmed published records in North America are in Coahuila and the Chihuahuan desert (Suárez-Morales et al. 2010), hence the known latitudinal range of this species extends from the 55◦ N to 26◦ N, including temperate highlands and arid areas of North America. Therefore the southernmost limit of the distributional range of this species in America is expanded with this record to 16◦ N in Chiapas, Mexico. Eucyclops pectinifer, Acanthocyclops einslei and Metacyclops cushae, in addition to A. clavipes show the influence of the Nearctic fauna in the surveyed area. On the other hand, the freshwater calanoids of the genus Mastigodiaptomus are considered Neotropical forms (Suárez-Morales and Elías Gutiérrez 2000), with high richness in the Americas, distributed from the southern region of the USA to


18 M.A. Gutiérrez-Aguirre and A. Cervantes-Martínez Guatemala and Cuba (Wilson and Yeatman 1959; Suárez-Morales and Elías-Gutiérrez 2000). Mastigodiaptomus albuquerquensis is considered the most widely distributed species of the genus, with records in the USA (south of Rocky Mountains) and records from highlands to lowlands in Mexico (Bowman 1986; Suárez-Morales and Reid 1998; Suárez-Morales and Elías-Gutiérrez 2000). On the other hand, M. nesus is distributed in the Caribbean region (Bowman 1986) and southeastern Mexico (Suárez-Morales et al. 1996; Cervantes-Martínez et al. 2005); whereas M. montezumae appears to be restricted to central Mexico (Santos-Silva et al. 1996), and records in Texas and southeastern Mexico of M. texensis have been confirmed (Wilson 1953; Elías-Gutiérrez et al. 2008). Other Mastigodiaptomus species have been recorded in a few systems; for instance M. reidae and M. maya inhabit one pond in Campeche, Mexico (Suárez-Morales and Elías-Gutiérrez 2000), or M. purpureus has been recorded only in Cuba, and M. amatitlanensis just in Guatemalan lakes (Wilson and Yeatman 1959). Therefore these four species appear to be endemic or potentially endemic forms; the distributional pattern of M. suarezmoralesi sp. nov. will be inferred from further studies in the region. Most of the species recorded in this research show Neotropical affinities (see Table 1), which is expected in this region of Mexico. According to Morrone (2006), the surveyed systems are in the Neotropical region, in the Usumacinta Province; this biotic province has been suggested because of the particular fauna (freshwater fish and molluscs) recorded there (B˘an˘arescu 1995; Miller 2009). Also, in the Usumacinta Province the usual freshwater species have Central and South American lineage (Miller 2009) and it is a region with high richness and endemism (Espinoza-Medinilla et al. 2006). This report increases the number of recognized Calanoida and Cyclopoida from Chiapas to 18, including one possible endemic species.

Acknowledgements We thank A. García-Morales, M. Elías-Gutiérrez and E. Quijano for collecting zooplankton samples in Chiapas and making them available to us. Support during sessions of SEM was provided by Guadalupe Nieto López, ECOSUR-Tapachula. Janet Reid and one anonymous reviewer improved with their comments the original manuscript.

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