Research Article |
Corresponding author: Martha Angélica Gutiérrez-Aguirre ( marguta71@gmail.com ) Academic editor: Danielle Defaye
© 2016 Martha Angélica Gutiérrez-Aguirre, Adrián Cervantes-Martínez.
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:
Gutiérrez-Aguirre MA, Cervantes-Martínez A (2016) A new species of Mastigodiaptomus Light, 1939 from Mexico, with notes of species diversity of the genus (Copepoda, Calanoida, Diaptomidae). ZooKeys 637: 61-79. https://doi.org/10.3897/zookeys.637.10276
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A new species of the genus Mastigodiaptomus Light, 1939, named Mastigodiaptomus cuneatus sp. n. was found in a freshwater system in the City of Mazatlán, in the northern region of Mexico. Morphologically, the females of this new species are distinguishable from those of its congeners by the following combination of features: the right distal corner of the genital double-somite and second urosomite have a wedge-shaped projection, the fourth urosomite has no dorsal projection and its integument is smooth. The males are distinct by the following features: the right caudal ramus has a wedge-shaped structure at the disto-ventral inner corner; the basis of the right fifth leg has one triangular and one rounded projection at the distal and proximal margins, respectively, plus one hyaline membrane on the caudal surface close to the inner margin; the aculeus length is almost the width of the right second exopod (Exp2); and the frontal and caudal surfaces of the right Exp2 are smooth. Furthermore, the analysis of the COI gene of M. cuneatus sp. n. has revealed that M. albuquerquensis (Herrick, 1895) is its nearest congener, with 18.64% of genetic distance. A key for the identification of the known species of the genus is provided.
COI gene, freshwater, Mexico, morphology, taxonomy
Diaptomidae G. O. Sars, 1903 is one of the most common families of freshwater copepods worldwide, some genera of this family have restricted distributional patterns and present endemic forms, as the genus Mastigodiaptomus Light, 1939. Recent studies of this genus in the Neotropical region have added new species of these diaptomids (
The fine structural features of the anatomy of the females and males of freshwater copepods are informative for species recognition. Researchers that have developed this idea concerning free-living copepods are
In the present work is provided an illustrated description of both sexes of one new species of the genus Mastigodiaptomus; it was found in the northern region of Mexico in a field collection carried out in 2014. The analysis was based upon the detailed micro-structure of the antennules, fifth legs, and prosomal integument. In addition, the sequences of the mitochondrial COI gene were used to assess the genetic divergence between the new species and seven congeners to incorporate molecular information into the species description.
Morphological analysis. The cephalic appendages, swimming legs and urosome of Mastigodiaptomus cuneatus sp. n. were examined using light microscopy and illustrated with the aid of a camera lucida. The specimens were dissected and appendages were mounted in glycerine.
The terminology and abbreviations used for the armament of each appendage and structure are based on
s setae
sp spine
sps spiniform process
ae aesthetasc
Enp1–Enpn first to “n” endopodal segment
Exp1–Expn first to “n” exopodal segment
P1–P5 Legs 1–5
The type material was deposited at the Colección de Referencia de El Colegio de la Frontera Sur (
Molecular analysis. Specimens (2 females, 3 males, and 3 copepodites) were preserved after capture in 96% ethanol and prepared for barcoding following standard methods. DNA was extracted using the HOTSHOT method (
Additionally, a search of GenBank and the public data of the Barcode of Life Data System (BOLD) produced sequences of Mastigodiaptomus albuquerquensis, M. patzcuarensis, M. cf. albuquerquensis (accession numbers for BOLD and GenBank in
Localities and sequence access for specimens surveyed herein, recorded in Mexico and Canada.
Species | Sample ID BOLD | Locality | Lat N | Long W |
---|---|---|---|---|
Hesperodiaptomus arcticus (Marsh, 1920) | CHU-CRU-0777 | Churchill, Manitoba, Canada | 58.772 | 93.844 |
Hesperodiaptomus arcticus (Marsh, 1920) | BIOUG01701-E09 | Churchill, Manitoba, Canada | 58.7715 | 93.844 |
Mastigodiaptomus cf. nesus | Cala039 | Minicenote, Quintana Roo, Mexico | 18.647 | 88.412 |
Mastigodiaptomus cf. nesus | Cala041 | Minicenote, Quintana Roo, Mexico | 18.647 | 88.412 |
Mastigodiaptomus cf. nesus | ZMXII-508 | La Esperanza, Q. Roo, Mexico | 19.471 | 88.029 |
Mastigodiaptomus cf. reidae | ZPLMX581 | Kohunlich, Q. Roo, Mexico | 18.447 | 88.825 |
Mastigodiaptomus cuneatus sp. n. | MAGA-0156 | El Camarón, Sinaloa, Mexico | 23.236 | 106.438 |
Mastigodiaptomus montezumae (Brehm, 1955) | HE-150a | Timilpan, Edo. Mex., Mexico | 19.887 | 99.739 |
Mastigodiaptomus montezumae (Brehm, 1955) | HE-151a | Timilpan, Edo. Mex., Mexico | 19.887 | 99.739 |
Mastigodiaptomus montezumae (Brehm, 1955) | HE-154a | Timilpan, Edo. Mex., Mexico | 19.887 | 99.739 |
Mastigodiaptomus montezumae (Brehm, 1955) | ZPLMX210 | km 25, Edo. Mex., Mexico | 19.486 | 99.745 |
Mastigodiaptomus reidae Suárez-Morales & Elías-Gutiérrez, 2000 | ZPLMX224 | Kohunlich, Q. Roo, Mexico | 18.447 | 88.825 |
Mastigodiaptomus reidae Suárez-Morales & Elías-Gutiérrez, 2000 | ZPLMX579 | Kohunlich, Q. Roo, Mexico | 18.447 | 88.825 |
Mastigodiaptomus reidae Suárez-Morales & Elías-Gutiérrez, 2000 | ZPLMX578 | Kohunlich, Q. Roo, Mexico | 18.447 | 88.825 |
Mastigodiaptomus texensis (M. S. Wilson, 1953) |
Cala012 | Boca del Puma, Q. Roo, Mexico | 20.871 | 87.055 |
Mastigodiaptomus texensis (M. S. Wilson, 1953) |
Cala016 | Boca del Puma, Q. Roo, Mexico | 20.871 | 87.055 |
Mastigodiaptomus texensis (M. S. Wilson, 1953) |
Cala065 | Verde Lucero, Q. Roo, Mexico | 20.866 | 87.077 |
Mastigodiaptomus texensis (M. S. Wilson, 1953) |
Cala066 | Verde Lucero, Q. Roo, Mexico | 20.866 | 87.077 |
Mastigodiaptomus texensis (M. S. Wilson, 1953) |
Cala069 | Verde Lucero, Q. Roo, Mexico | 20.866 | 87.077 |
These sequences were downloaded from the BOLD project files Mastigodiaptomus of Mexico (MALB), Microcrustacean from Mexico (MCM), and Zooplankton II (ZPII) and compared with our sequence of M. cuneatus sp. n., this latter sequence is into the project MCM. In these project files, the electropherograms, sequence data, photographs, primers data, and collection details are available (on the Barcode of Life Data System http://www.boldsystems.org). Fifty-two COI gene sequences > 500 bp were used for the analysis, and BOLD Aligner and the ID Tree using the model Kimura 2 parameter (K2P;
One adult female dissected on one slide:
One adult male dissected on one slide:
Four adult females and five adult males preserved in 90% ethanol with a drop of glycerine.
Two adult females and two adult males preserved in 90% ethanol: CNCR-31861. Collected 28.VIII.2014. Same collectors.
A lagoon called Laguna El Camarón in Avenida Insurgentes, Mazatlán, Sinaloa City, México; 23°14'10"N; 106°26'18"W.
The name of the species means “wedged” in Latin and refers to the chitinous protuberance present on the right disto-lateral corner of the first and second urosomites in females, and on the right caudal ramus on the ventral surface in males.
Adult female: Cuticle surfaces of prosomal somites smooth dorsal and laterally (Fig.
Mastigodiaptomus cuneatus sp. n. Adult female, holotype. A Rostrum, lateral B Rostrum, frontal C Wing of fifth pediger, genital double-somite, and second urosomite, lateral right view D Wing of fifth pediger, lateral, left view E Urosome, ventral F Genital field G Fifth leg, frontal. Scale bars: 50 µm.
Adult male: The cuticle surfaces of prosomal somites are smooth dorsally and laterally (Fig.
Mastigodiaptomus cuneatus sp. n. Adult male, allotype. A Rostrum, frontal B Wing of fifth pediger and first urosomite, lateral right view C Wing of fifth pediger and first urosomite, lateral left view D Right antennule E Fifth pediger and urosome, ventral. Scale bars: 50 µm (A–C); 100 µm (D, E).
Smooth prosomal somites; body length 1500-1700 µm in paratypes including caudal ramus, n = 6 (Fig.
Antennule: 25-segmented, extending beyond the caudal ramus (Fig.
Antenna: Coxa with one long seta; basis with 2 setae; Exp 7-segmented with 1, 3, 1, 1, 1, 1, 4 setae, respectively. Enp 2-segmented, Enp1 with 2 setae plus a row of spine-like setae. Inner lobe of Enp2 bearing 9 long setae, outer lobe with 7 setae and a group of tiny spinules (Fig.
Mandible: Eight teeth on gnathobase (6 of these teeth bifid) with a movable seta at tip. Rectangular, nude coxa. Basis with 4 long setae. Enp two-segmented, Enp1 with 4 setae, Enp2 with 2 distal pectens and 9 long setae. Exp 4-segmented, with 1, 1, 1, and 3 long setae, respectively (Fig.
Maxillule (Fig.
Maxilla (Fig.
Maxilliped (not figured): Same structure as described and illustrated for Mastigodiaptomus albuquerquensis and M. patzcuarensis (see
P1-P4: The number of segments on endopods and exopods of P1 to P4, as described for copepods that belong to the Diaptomidae family (
Setation formula of the swimming legs in Mastigodiaptomus cuneatus sp. n. (spine in Roman numerals, seta in Arabic numerals).
Coxa | Basis | Exp | Enp | |
---|---|---|---|---|
P1 | 0-1 | 0-0 | I-1; 0-1; I-3-2 | 0-1; 1-2-3 |
P2 | 0-1 | 0-0 | I-1; I-1; I-3-3 | 0-1; 0-2; 2-2-3 |
P3 | 0-1 | 0-0 | I-1; I-1; I-3-3 | 0-1; 0-2; 2-2-3 |
P4 | 0-1 | 1-0 | I-1; I-1; I-3-3 | 0-1; 0-2; 2-2-3 |
Fifth pediger wings and urosome: Right wing of fifth pediger with 2 spines, one dorsal and one ventral (Fig.
Fifth leg (Fig.
Prosomites smooth in dorsal view; left antennule reaching anal somite. Body length 1400-1500 µm in paratypes including caudal ramus, n = 7 (Fig.
Right antennule (Fig.
Spiniform process on segment 10 very short, reaching only distal third of its segment; that on segment 11 short, reaching proximal third of the next segment. Convergent spiniform processes on segments 13 and 14. Base of stout spiniform process on segment 13 almost as wide as the length of its segment. Segment 20 is 3.6 times as long as wide, bearing a hook-like projection (less than the half length of penultimate segment) with a smooth hyaline membrane.
Antennule, antenna, mandible, maxillule, maxilla, maxilliped, and P1-P4 as described for female.
Right wing of fifth pediger with 1 tiny dorsal spinule and 1 ventral spine (Fig.
Urosome: Urosomites nude dorsally and ventrally. First urosomite with thin spine on right side and fold on left side (Fig.
P5: Coxal segments with strong spines on caudal view; left and right basis with a lateral seta (Fig.
Left basis with a triangular protuberance on distal margin of frontal surface (Fig.
Right basis basally and distally projected: basal projection rounded whereas distal projection triangle-shaped; one semi-triangular sclerotization on caudal surface of right basis (Fig.
The nucleotide sequence (607 bp) obtained for specimen MAGA-0156 (one adult male), identified as M. cuneatus sp. n. is shown below:
GGAGCCTGGTCAGGCATAGTAGGAACAGGCCTTAGAATGATTATTCGGATGGAGTTAGGACAAGCCGGGTCTTTAATTGGAGATGACCAAATTTATAATGTAGTAGTTACTGCTCATGCTTTTGTTATAATTTTTTTTATGGTGATACCTATTTTAATTGGGGGGTTTGGTAATTGGCTTGTTCCGTTAATATTAGGTGCAGCGGATATAGCTTTCCCTCGAATAAATAATATAAGATTTTGATTTTTATTGCCAGCTTTAGTCATATTGTTATCTAGGTCGCTTGTTGAAAGAGGGGCGGGAACAGGGTGAACTGTGTATCCCCCCCTGTCTAGCAACATTGCCCATGCTGGCAGGTCCGTTGATTTTGCTATTTTTTCGCTTCATTTAGCTGGGGTTAGGTCTATTTTGGGCGCAGTAAATTTTATTAGCACATTAGGAAATTTGCGGGCGTTTGGAATAATTTTAGATCGAATACCACTTTTTGCTTGAGCCGTTTTAATCACGGCTATCTTGTTATTGCTTTCTCTTCCTGTTTTAGCCGGGGCGATTACAATGCTTCTTACAGATCGGAACCTCAACTCAAGATTTTATGAT.
The K2P maximum distance between the surveyed species reaching 5.52% (Table
Mastigodiaptomus cuneatus sp. n. is assigned to the genus Mastigodiaptomus because it fulfils all the morphological generic criteria as given in
Mastigodiaptomus cuneatus sp. n. (from northern Mexico) appeared to be morphologically close to M. amatitlanensis (from Lago Amatitlán, Guatemala). Similarities between these species in females include the presence of one protrusion on the second urosomite and the bulbose lateral margins of genital double-somite. The similarities in males are the short aculeus and the lack of hyaline membrane on the right Exp2 of the fifth leg.
However, M. cuneatus sp. n. can be separated from M. amatitlanensis by the following features: the dorsal projection on the last pediger absent vs. present; the genital double-somite with vs. without a protrusion on the distal right side; on the genital double-somite, the right spine located at a higher level than the left spine vs. both left and right spines placed at same level; and the endopod of fifth leg long and 2-segmented vs. short and 1-segmented.
The males of these species show more morphological differences in the fifth leg: the caudal surface of the right basis is bulbose with the oblique, medial, angulose and curved cuticular process in M. cuneatus sp. n. in comparison to the rectangular basis with a transversal, distal, cuneiform lamella in M. amatitlanensis. In addition, the distal margins of the left and right endopods bear short setules in M. cuneatus sp. n. whereas in M. amatitlanensis these distal margins bear one slender seta. The aculeus on the right Exp2 is clearly straight in M. cuneatus sp. n. but short, distal and curved in M. amatitlanensis. The Exp2 is smooth in M. cuneatus sp. n. but in M. amatitlanensis an oblique ridge on the caudal surface is present. Finally, we assume that the wedge on the right caudal ramus present in M. cuneatus sp. n. is absent in M. amatitlanensis because there is no mention of a similar feature in
Results related with the COI gene suggested that M. cuneatus sp. n. is genetically closest to M. albuquerquensis s. str. and the species recorded in Mexico with one sclerotization (similar to the half wing of a butterfly) on the right basis of fifth leg of males such as M. patzcuarensis. As previously discussed (see
Whereas the distal margins of prosomites are pilose in females and males of M. patzcuarensis, these structures are nude in M. cuneatus sp. n and they have tiny spinules on lateral margins in M. albuquerquensis. The right Exp2 bearing one curved hyaline membrane and the aculeus is 2-3 times longer than the segment’s width in M. albuquerquensis and M. patzcuarensis; this Exp2 is nude with the aculeus shorter or as long as the segment’s width in M. cuneatus sp. n. There are no protrusions on the urosomites of males or females of M. albuquerquensis or M. patzcuarensis, but such structures do occur in M. cuneatus sp. n.
Sequences of the COI gene of M. maya, M. suarezmoralesi, M. amatitlanensis, M. purpureus, and M. nesus from their type localities or areas of their primary distribution, are not yet available for comparison and then the genetic distances between the species showed in Fig.
Mastigodiaptomus is considered a Neotropical genus and the species with the widest distribution are M. albuquerquensis (South of USA and North of Mexico), M. patzcuarensis, M. montezumae (Central Mexico), M. nesus (Caribbean and south eastern Mexico), and M. texensis (Texas and south eastern Mexico), whereas the species that are assumed to have restricted distribution or endemics are M. reidae, M. maya, M. purpureus, M. amatitlanensis, M. suarezmoralesi (see
Morphological and genetic differences were found when M. cuneatus sp. n. was compared with the ten known Mastigodiaptomus species, particularly in the female and male urosomes, the male right antennule and fifth legs, and in the COI gene sequence. This report increases the number of recognized species of Mastigodiaptomus to eleven. Mastigodiaptomus cuneatus sp. n. appears to be part of the M. albuquerquensis complex.
Males
1 | Spiniform process on segment 16 of right antennules strongly developed almost as long as its segment width; right basis of P5 with one basal subrectangular protuberance | Mastigodiaptomus reidae |
– | Spiniform process on segment 16 of right antennules reduced or absent; right basis of P5 with basal rounded protuberance or without basal protuberance | 2 |
2 | Right basis of P5 with only one lobular protuberance on basal-medial margin, no chitinous lamella or lamellae (on caudal view) | 3 |
– | Right basis of P5 with chitinous lamella or lamellae and with or without rounded protuberance on basal-medial margin (on caudal view) | 4 |
3 | Lobular protuberance of right basis of P5 large; right Exp2 of P5 with two semicircular transverse lamellae, and one longitudinal “Y” shaped ridge; antepenultimate antennular segment with a fang-like process | M. montezumae |
– | Lobular protuberance of right basis of P5 short; right Exp2 of P5 with a low rounded protuberance on outer margin; antepenultimate antennular segment with wide knob-like process | M. maya |
4 | Right basis of P5 with one chitinous lamella | 5 |
– | Right basis of P5 with more than one chitinous lamella | 8 |
5 | Chitinous lamella of right basis of P5 semi-circular, on medial margin | 6 |
– | Chitinous lamella of right basis of P5 cuneiform, transversal; or semi-triangular, on caudal side | 7 |
6 | Right Exp2 of P5 with two short semi-circular lamellae (one medial and one lateral); aculeus with 50% of the length of its segment; short spiniform process on antennular segment 14 | M. purpureus |
– | Right Exp2 of P5 with one long quadrangular lamella (on caudal side) aculeus with 70–90% of the length of its segment; long spiniform process on antennular segment 14 | M. nesus |
7 | Caudal surface of right basis of P5 with one triangular protuberance on distal margin, and one rounded protuberance on basal-medial margin; right Exp2 of P5 nude; right furcal ramus with one wedge-like structure at disto-inner corner of ventral surface | M. cuneatus sp. n. |
– | Caudal surface of right basis of P5 without protuberances, almost rectangular; right Exp2 of P5 with one straight ridge, obliquely directed | M. amatitlanensis |
8 | Left Exp2 of P5 distally truncated and denticulate; aculeus inserted subterminally on Exp2 of P5 | M. texensis |
– | Left Exp2 of P5 distally attenuated (triangular-shape) aculeus inserted on the second third of Exp 2 of P5 | 9 |
9 | Aculeus shorter than the length of right Exp2 of P5 with long spinules on medial margin; two short semi-circular lamellae on medial margin of right Exp2 of P5; second to forth urosomites with denticles on dorsal surfaces | M. suarezmoralesi |
– | Aculeus subequal or longer than the length of right Exp2 of P5 with short spinules on medial margin; one long curved hyaline lamella on right Exp2 of P5; dorsal surfaces of urosomites nude | 10 |
10 | Short spines on rostrum: 2.2–3.0 times longer than width; cuticular surfaces of prosomites nude; 1.37–1.82 mm of body length including furcal ramus | M. albuquerquensis |
– | Long spines on rostrum: 3.5–5.0 times longer than width; hair-like setae on ventral and distal margins from second to fifth prosomites; 0.92–1.1 mm of body length including furcal ramus | M. patzcuarensis |
Females
1 | Hair-like setae only on medial margin of furcal ramus | 2 |
– | Hair-like setae on both, medial and lateral margins of furcal ramus | 3 |
2 | Symmetric genital double-somite, almost parallel lateral margins with short spines on left and right margins | Mastigodiaptomus purpureus |
– | Asymmetric genital double-somite, bulbose lateral margins with short spines on left and right margins | M. reidae |
3 | Symmetric genital double-somite, almost parallel lateral margins; two-segmented Enp of P5 bearing one apical spinule longer than the endopodal width | 4 |
– | Asymmetric genital double-somite, bulbose lateral margins; one or two-segmented Enp of P5 bearing two apical spinules shorter than the endopodal width | 5 |
4 | Enp of P5 longer than the inner margin of Exp1 of P5; long lateral sensilla of coxal segment of P5 | M. texensis |
– | Enp of P5 shorter than the inner margin of Exp1 of P5; short lateral sensilla of coxal segment of P5 | M. maya |
5 | One or two urosomites with a chitinous protuberance on the right disto-lateral corner | 6 |
– | Urosomites with straight posterior margins, no protuberances are present | 7 |
6 | Second urosomite with a spine-like protuberance on the right disto-lateral corner; one-segmented Enp of P5 | M. amatitlanensis |
– | Genial double-somite and second urosomite with chitinous protuberance on the right disto-lateral corner; two-segmented Enp of P5 | M. cuneatus sp. n. |
7 | Genital double-somite produced, or curved and wrinkled on the right disto-lateral margin | 8 |
– | Genital double-somite straight on the right disto-lateral margin | 9 |
8 | Two-segmented Enp of P5, as long as medial margin of Exp1; genital double-somite curved and wrinkled on the right disto-lateral margin | M. suarezmoralesi |
– | Two-segmented Enp of P5, shorter than the half length of medial margin of Exp1; genital double-somite produced on the right disto-lateral margin | M. montezumae |
9 | One-segmented Enp of P5; left and right spines of genital double-somite inserted at same level; ventral spine of right wing (of last prosomite) directed to the posterior region of the body | M. nesus |
– | Two-segmented Enp of P5; right spine of genital double-somite inserted more anteriorly than left spine; ventral spine of right wing (of last prosomite) directed to the dorsal region of the body | 10 |
10 | Short spines on rostrum: 1.5–3.6 times longer than width; tiny spines on ventral surface of each prosomites; 1.47–1.87 mm of body length including furcal ramus | M. albuquerquensis |
– | Long spines on rostrum: 3.6–4.0 times longer than width; hair-like setae on ventral and distal margins from second to fifth prosomites; 0.9–1.3 mm of body length including furcal ramus | M. patzcuarensis |
We received grants from the Universidad de Quintana Roo and National Council of Science and Technology (CONACYT) through the Mexican Barcode of Life (MEXBOL) project CONACyT 271108, Red Temática Código de Barras de la Vida (Continuidad de Redes Temáticas). We are grateful with the academic edition of two native English-speaking editors. We thank professors and students of Instituto Tecnológico de Mazatlán (ITMAZ) for collecting zooplankton samples and making them available to us. We are grateful to Danielle Defaye, Y. Ranga Reddy and an anonymous reviewer who made valuable comments and suggestions to improve the manuscript.