Research Article |
Corresponding author: Eduardo Suarez-Morales ( esuarez@ecosur.mx ) Academic editor: Danielle Defaye
© 2015 Eduardo Suarez-Morales, Roberto Javier Almeyda-Artigas.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Suárez-Morales E, Almeyda-Artigas RJ (2015) A new genus and species of cyclopoid (Crustacea, Copepoda, Cyclopinidae) from a coastal system in the Gulf of Mexico. ZooKeys 534: 17-34. https://doi.org/10.3897/zookeys.534.6019
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A new, monotypic genus of the interstitial marine cyclopoid copepod family Cyclopinidae G.O. Sars, 1913 is described from male and female specimens collected at Laguna de Términos, a large coastal lagoon system in the southern Gulf of Mexico. Mexiclopina campechana gen. et sp. n. cannot be adequately placed in any extant genus within the family. It differs from other cyclopinid genera in having a unique combination of characters including: 1) absence of modified brush-like seta on the mandibular exopod; 2) maxillule exopod with stout setal elements and brush-like setae absent; 3) basis of mandible with one seta; 4) presence of a modified seta on endopod of fourth leg; 5) fifth leg exopod unsegmented, armed with three elements in the female and five in the male; 6) intercoxal sclerite of first swimming leg with two medial spiniform processes on distal margin. The new genus is monotypic and appears to be most closely related to Cyclopina Claus, 1863 and Heptnerina Ivanenko & Defaye, 2004; the new species was compared with species of Cyclopina and it resembles C. americana Herbst, 1982 and C. caissara Lotufo, 1994. This is the second record of a species of Cyclopinidae in Mexico and the first in the Gulf of Mexico; the number of cyclopinid species recorded from the Americas is now 13.
Free-living copepods, coastal zooplankton, taxonomy, interstitial copepods
The cyclopoid copepod family Cyclopinidae G.O. Sars, 1913 is one of the most diverse and successful among the benthic marine poecilostomatoid/cyclopoid copepods. It contains 12 valid genera (
Laguna de Términos, in the Mexican state of Campeche, in the southern Gulf of Mexico (between 18°26’ and 18°44’N; 91°13’ and 91°54’W) is one of the largest lagoon estuarine ecosystems of the gulf; it has a significant ecological and economic importance in southeastern Mexico because of its permanent connection to the sea and high productivity and diverse fish fauna (
Night zooplankton samples were obtained on February 13, 2015 with three hand nets (two of 100 and one of 200 µm) in shallow areas (depth: 60–120 cm) of the lagoonal system, particularly at Isla Tortuga (18°44'29.3"N; 91°29'44.6"W). Water temperature was 25 °C, salinity 28psu, and pH slightly alkaline (7.5). Trawls followed a parallel course with respect to the coastline. Samples were placed in a bucket with 5 liters of water; copepods were isolated alive 5 hours after collection, they were later on fixed in 4% formaldehyde buffered with borax (30 g/l of formaldehyde at 40%) and kept in a 5% glycerin/ 70% ethanol solution. More than 35 male and female specimens were taxonomically examined in the laboratory; specimens were processed, dissected and examined following
Mexiclopina campechana sp. n.
The genus name is composed by the prefix ‘Mexi’ in reference to Mexico, the country from which it was collected and the suffix ‘clopina’ to show its affinity with the genus Cyclopina.
First pedigerous somite free, posterolateral margins of second and third pedigerous somites slightly produced. Caudal ramus with six setae, seta I absent. Female antennule 10-segmented, 6th segment longest; male antennule 15-segmented. Antenna with single exopodal seta. Mandibular palp with one basal seta, 2-segmented endopod and 4-segmented exopod; fourth exopodal segment with two ordinary setae. Maxillule endopod with seven setae, exopod with four short, stout elements. Maxilliped 6-segmented. Legs 1–4 with 3-segmented rami; spine and seta formula as for type species. Endopod segment 3 of leg 4 with modified outer seta. Female fifth leg exopod unsegmented, bearing three elements (setae/spines); male fifth leg exopod unsegmented, armed with five elements, three setae, two spines. Sixth leg with two setae in female, and with two setae plus short spiniform process in male.
Holotype. Adult female, dissected, mounted in glycerin sealed with Entellan (ECO-CHZ-09298), Laguna de Términos, Campeche, Mexico (18°44'29.3"N;91°29'44.6"W), collected February 13, 2015 by R. J. Almeyda-Artigas, C. Lara-Bautista, and C. Chamorro-García. Allotype male, dissected, same site, date, and collectors (ECO-CHZ-09299). Paratypes. Two adult females, dissected, slides (ECO-CHZ-09300), 6 adult females, undissected, ethanol-preserved, vial (ECO-CHZ-09301); 3 adult males, undissected, ethanol-preserved, vial (ECO-CHZ-09302). One female, one male, specimens undissected, ethanol-preserved, same locality and collectors (
Length range (including caudal rami) of type specimens (n=11) 350–400 µm, average: 372 µm. Body cyclopiform (Fig.
Anal somite with ventral and dorsal surfaces smooth, posterior margin ornamented with row of minute spinules along ventral margin at point of insertion of caudal rami. Anal operculum smooth. Caudal ramus (Fig.
Antennule (Fig.
Antenna (Fig.
Mandible (Fig.
Maxillule (Figs
Maxilla (Fig.
Maxilliped (Figs
Legs 1–4 (Fig.
Mexiclopina campechana gen. et sp. n., female holotype. A urosome showing fifth legs, ventral view B first swimming leg with exopod C endopod of first leg D third leg E fourth leg, asterisk indicates modified seta on endopod F intercoxal sclerite of first leg showing spiniform processes G same, third leg H same, fourth leg. Scale bars: 50 µm (A); 10 µm (B–H).
Leg 1 (Fig.
Legs 2–3: each with exopodal ramus longer than endopod, intercoxal sclerites with distal margin smooth (Fig.
Leg 4 (Fig.
Armature formula of swimming legs as:
Leg 5 (Figs
Leg 6 (Fig.
Length of allotype 325 µm, of rest of male paratypes (n=7): 313–328 µm, average 321 µm. Body cyclopiform, smaller than female and slightly narrower (Figs
Mexiclopina campechana gen. et sp. n., from the Gulf of Mexico, SEM-prepared female. A fifth leg and sixth leg armature (indicated by asterisks); male specimen: B ventral view of mouthparts including maxillule (mxl), maxilla (mx), and maxilliped (mxp) C preanal and anal somites and caudal rami D habitus, ventral view E legs 1–4 showing ornamentation and part of armature, ventral view; leg 1 (P1) and leg 3 (P3) indicated.
Mexiclopina campechana gen. et sp. n., from the Gulf of Mexico, SEM-prepared males. A cephalic area showing digeniculate antennules (note flattened aesthetasc-mfs) and mouthparts including maxilla (mx) and maxilliped (mxp) B distal segments (9-15) of antennule showing position of pectinate setae (asterisks) C detail of maxillipedal (mxp) ornamentation of basis and endopodal segmentation and armature, ventral view D fifth leg(P5) partly damaged but with distinctive serrate spine and sixth leg (P6) with inner spiniform process (arrowed) E fifth leg F rostrum, geniculate antennules and antennae, ventral view; another male specimen.
Leg 5 (Figs
Leg 6 represented by flat, rounded plate bearing two slender setae and an inner spiniform process (Figs
Laguna de Términos (18°44'29.3"N; 91°29'44.6"W), state of Campeche, Mexico, southern Gulf of Mexico.
The species is named after the state of Campeche in southeast Mexico. Gender is feminine.
The lagoon has a length of 70 km and 30 km at its widest sector. It has extense coverage of seagrass beds (mainly Thalassia testudinum), mangrove areas and zones with no vegetation. It is a shallow system, (average depth = 2.5 m). The lagoon receives freshwater input from several rivers. Most of its bottom is covered by sediments of sand, silt and clay with a high content of calcium carbonate mainly in the vicinity of Boca de Puerto Real (between 50 and 70%).
Based on the first examination of these specimens, they were tentatively identified as a species of Cyclopina Claus, 1863 by the combined display of the following features: 10-segmented female antennule with sixth antennulary segment being longest, antenna with single exopodal seta; female fifth leg exopod with three armature elements, the apical seta flanked by two spines; leg 1 with 3-segmented endopod; and caudal seta I absent (cf.
Other remarkable features of the new genus include: 1) the short, stout distal setae of the exopodal segment of the maxillule (asterisks in Fig.
Because of the close morphological resemblance of the new species with Cyclopina, we performed a comparison with the most closely related species of this genus. Only a few species of Cyclopina have a female leg5 with the inner spine of the exopodal segment less than half the length of the outer spine, the latter being longer than the segment itself (
The new species differs from C. esilis in the display of a long terminal seta on the exopod of mandibular palp; it is the longest and is slightly broader than the rest of exopodal setae; contrastingly, this seta is remarkably short and modified, umbrella-like, in C. esilis (
Mexiclopina campechana sp. n. differs from C. americana in body shape, with the third and fourth pedigerous somites strongly produced posteriorly, the process of the fourth somite reaching well beyond the posterior margin of the fifth pedigerous somite (Fig.
The new species of Mexiclopina shows also some resemblance with C. kieferi, but in this species the external spine of the female fifth leg is 1.2–1.5 times as long as the internal spine (vs. 2.5 in the new species), the caudal rami are clearly longer than the anal somite and have a length/width ratio of 2.6 (
Males are known for only about half the known nominal species of Cyclopina (
The male fifth leg of the new species has 5 elements on the exopodal segment, thus diverging from most species of Cyclopina for which males have been described thus far. This feature is shared only with C. esilis, C. caissara, C. kieferi, C. amita, and C. confusa, but the latter has an ornamented anterior surface of the female fifth leg, thus diverging from the smooth condition of the same surface in M. campechana.
The copepod fauna of the Laguna de Términos has been known mainly from plankton surveys (
This work increases the number of species of cyclopinids known from the Americas (
We gratefully acknowledge the support by Guadalupe Nieto, Laboratorio de Microscopía Electrónica de Barrido, El Colegio de la Frontera Sur (