Research Article |
Corresponding author: Samuel Gómez ( samuelgomez@ola.icmyl.unam.mx ) Academic editor: Kai Horst George
© 2020 Samuel Gómez.
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:
Gómez S (2020) On some new species of Stenheliinae Brady, 1880 (Copepoda, Harpacticoida, Miraciidae) from north-western Mexico, with the proposal of Lonchoeidestenhelia gen. nov. ZooKeys 987: 41-79. https://doi.org/10.3897/zookeys.987.52906
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Quarterly sampling campaigns during 2019 to study the diversity of meiofauna in a polluted estuary in northwestern Mexico revealed the subfamily Stenheliinae Brady, 1880 as one of the most important contributors to the diversity of benthic harpacticoids. Two new stenheliin species are described here. One of them was assigned to the, so far, monotypic genus Lonchoeidestenhelia gen. nov. defined by the autapomorphic modified proximal outer spinules on the sigmoid process of the male P2 ENP2. The other species was assigned to Willenstenhelia Karanovic and Kim, 2014. Lonchoeidestenhelia gen. nov. shares the armature formula of the P1 EXP2 with Stenhelia, Anisostenhelia, and Beatricella, but seems to bear a sister-group relationship with the former two genera by the loss of one inner seta on the P2–P3 EXP3, the presence of two outer spine-like elements on the male P5 EXP, and the displacement of the outer spine and medial and inner distal setae of P2 ENP3, to an apical and subapical inner position, respectively, but is more closely related to Anisostenhelia by the overall shape of the male P2 ENP2. Willenstenhelia reducta sp. nov. is attributed to a group of species composed of Wi. minuta, Wi. urania, and Wi. terpsichore characterized by the strongly reduced inner seta of the female P5 baseoendopod, but differs in the discrete female P5 baseoendopods and in the presence of one outer seta only on that segment. Willenstenhelia reducta sp. nov. is defined here by the autapomorphic loss of the outermost seta of the female P5 baseoendopod.
Diversity, new genus, new species, pollution, taxonomy, Willenstenhelia
A series of quarterly sampling campaigns were carried out during 2019 in the frame of a short-term project financed by the Universidad Nacional Autónoma de México, aiming at assessing the present effects of organic pollution on the distribution and diversity of meiofauna in an estuary in northwestern Mexico. Preliminary analyses revealed the subfamily Stenheliinae Brady, 1880 (Miraciidae Dana, 1846) to be one of the most important contributors to the overall diversity and density of benthic harpacticoids. In addition to the new species presented here, Pseudostenhelia wellsi Coull and Fleeger, 1977 was also found, although its overall contribution to the diversity and density of harpacticoid copepods in the study area was far less important. Here I present the description of two new stenheliin species. One of them was assigned to a new genus, Lonchoeidestenhelia gen. nov. as L. prote sp. nov., defined here by the autapomorphic modified proximal outer spinules on the sigmoid process of the male P2 ENP2. Some comments on the relationships amongst Stenhelia Boeck, 1865, Anisostenhelia Mu and Huys, 2002, Beatricella Scott, 1905, and Lonchoeidestenhelia gen. nov. are given. The other species was assigned to Willenstenhelia Karanovic and Kim, 2014 as Wi. reducta sp. nov. Some comments on the relationships amongst the species of Willenstenhelia are given.
Sediment samples were taken from a series of sampling stations along Urías system (Fig.
Sampling locations in Urías estuary, Mazatlán, Sinaloa State, Mexico. Coordinates as follows: stn 1 (23.15194°N, 106.3128°W); stn 2 (23.1587°N, 106.3326°W); stn 3 (23.1735°N, 106.3504°W); stn 4 (23.1840°N, 106.3579°W); stn 5 (23.2056°N, 106.3715°W); stn 6 (23.2123°N, 106.3780°W); stn 7 (23.2174°N, 106.3917°W); stn 8 (23.2128°N, 106.4047°W); stn 9 (23.1904°N, 106.4121°W); stn 10 (23.1815°N, 106.4214°W). Map data 2020 Google.
Illustrations and figures were made from whole individuals and their dissected parts using a Leica DMLB microscope equipped with L PLAN 10× eyepieces, N PLAN 100× oil immersion objective, and drawing tube. The dissected parts were mounted on separate slides using lactophenol as mounting medium.
acro acrothek;
ae aesthetasc;
BENP baseoendopod;
ENP endopod;
EXP exopod;
EXP/ENP1(2,3) exopodal/endopodal 1st(2nd, 3rd) segment;
P1–P6 first to sixth legs.
The type material was deposited in the Copepoda collection of the Instituto de Ciencias del Mar y Limnología, Unidad Académica Mazatlán (ICML–EMUCOP).
Family Miraciidae Dana, 1846
Subfamily Stenheliinae Brady, 1880
Lonchoeidestenhelia prote sp. nov., by monotypy.
(based on its only species, L. prote sp. nov.). Stenheliinae. Female: Anal somite twice as long as broad; anal operculum rounded, with minute spinules along its posterior margin, with one sensillum on each side. Caudal rami cylindrical, twice as long as broad, and slightly longer than anal somite; with seven setae, of which seta I spine-like, setae IV and V with fracture plane, rat-tail-like. Rostrum trapezoidal, not fused to cephalothorax, bifid, with medial pore and two subdistal sensilla. Antennule seven-segmented; all setae smooth except for one and two pinnate setae on first and second segments; second and third segments each with one seta with fracture plane; sixth and seventh segments each with two articulated setae; aesthetasc on segments 4 and 7. Antenna with allobasis; exopod three-segmented, armature formula 1,1,[1 lateral + 3 apical, two of which fused basally]. Mandible with elongate basis tapering distally; exopod arising from short pedestal, one-segmented, ca. 4× as long as wide, tapering distally, with three lateral and three apical slender setae; endopod recurved, twisted over exopod, with three lateral setae, and five distal elements (one short seta and long pinnate element fused basally and to endopod, one slender pinnate and one strong bare element, and one long element fused to endopod and with hyaline flange in middle part). Maxillule without modified elements on arthrite; basis with two endites, proximal endite with four, distal endite with three slender setae; exopod and endopod fused basally, separated from basis, one-segmented, endopod with four setae, exopod with two setae. Maxilliped subchelate; syncoxa with one bare and two spinulose strong elements; basis with two slender distal setae unequal in length; endopod one-segmented, slender, with one claw and one accompanying seta. Armature seta of P1–P4 as follows:
P1 | P2 | P3 | P4 | |
---|---|---|---|---|
EXP | 0,0,022 | 1,1,123 | 1,1,223 | 1,1,323 |
ENP | 1,1,111 | 1,2,121 | 1,1,221 | 1,1,221 |
P5 baseoendopod transversely elongate, with five setae, all setae normal; exopod with six setae. Male: Habitus, anal somite, and caudal rami as in female. Sexual dimorphism expressed in A1, P2 ENP, P5, and P6. Antennule 10-segmented, haplocer; all segments smooth except for first and seventh segment with spinules; all setae smooth except for one and two pinnate setae on first and second segments, and one and two modified spine-like elements on seventh and eighth segments; aesthetasc on third, fifth, and tenth segments. P2 ENP2 transformed, proximal half globular, distal half triangular, without hyaline flange, with two inner (one proximal and one medial) small setae, one inner subdistal strong pinnate element, and one apical sigmoid pinnate process with proximal row of modified (lanceolate) outer spinules. Baseoendopods of both P5 fused medially, each endopodal lobe with two setae, of which the inner well-developed, the outer small; exopod small, discrete, with four elements, of which two outermost spine-like. P6 asymmetrical, only one leg functional, each leg with three normal setae.
The genus name from the Greek λογχοειδής, lonchoeidḗs̱, lanceolate, makes reference to the shape of the proximal spinules on the distal outer process of the male P2 ENP2. Gender feminine.
One female holotype (ICML–EMUCOP-180119-01), one male allotype (ICML–EMUCOP-180119-02), and 14 paratypes (10 females and four males) (ICML–EMUCOP-180119-03) preserved in alcohol, and two female (ICML–EMUCOP-180119-05, ICML–EMUCOP-180119-06) and one male (ICML–EMUCOP-180119-07) paratypes dissected and mounted onto 11, six and seven slides, respectively, all from the type locality; six paratypes (two females and four males) (ICML–EMUCOP-180119-04) from stn 1, preserved in alcohol; one female paratype partially dissected (ICML–EMUCOP-180119-08) (P1-P4 dissected and mounted onto one slide, the rest left intact and preserved in alcohol), and nine paratypes (eight females and one male) (ICML–EMUCOP-180119-09) from stn 10, preserved in alcohol; 18 Jan. 2019. S. Gómez leg.
One intersexual individual partially dissected (ICML–EMUCOP-180119-10) (P1-P4 dissected and mounted onto one slide, the rest left intact and preserved in alcohol) from stn 4; 18 Jan. 2019. S. Gómez leg.
Stenheliinae. Anal operculum present, with minute spinules along posterior margin. P1 EXP2 without inner armature. P2–P4 EXP1 with inner seta. Armature formula of P2 EXP3 and P3 EXP3, 123 and 223, respectively. Female P2 ENP3 with outer apical spinous process, with displacement of medial and inner apical setae to subapical inner margin, the latter setae normal, not swollen basally. Female P5 baseoendopod without modified setae. Male P2 ENP2 without hyaline flange; outer apical sigmoid, bipinnate, flagellate process with incomplete suture indicating original articulation with the supporting segment, with longitudinal row of modified lanceolate spinules proximally. Outer spine of the male P4 ENP3 normal, not sexually dimorphic. Male P5 EXP and baseoendopod not fused; exopod with two outermost elements modified into spines. Innermost seta of the male P6 normal.
Female. Total body length measured from tip of rostrum to posterior margin of caudal rami ranging from 415 µm to 563 µm (mean, 491 µm; n, 12; total body length of holotype, 563 µm); habitus pyriform, widest at posterior end of cephalothorax in dorsal view, tapering posteriad (Fig.
Prosome (Fig.
Urosome (Figs
First urosomite (fifth pedigerous somite): Visibly narrower than preceding somites in dorsal view (Fig.
Genital double-somite: Slightly wider than long, widest at proximal half; with dorsolateral internal rib marking original division between second (genital) and third urosomite (Figs
Fourth urosomite: With spinular ornamentation (Fig.
Fifth urosomite: With spinular ornamentation (Fig.
Anal somite (Figs
Caudal rami (Figs
Rostrum (Figs
Antennule (Fig.
Antenna (Fig.
Mandible (Fig.
Maxillule (Fig.
Maxilla (Fig.
Maxilliped (Fig.
P1 (Fig.
P2 (Fig.
P3 (Fig.
P4 (Fig.
Setal formula of swimming legs as follows:
P1 | P2 | P3 | P4 | |
---|---|---|---|---|
EXP | 0,0,022 | 1,1,123 | 1,1,223 | 1,1,323 |
ENP | 1,1,111 | 1,2,121 | 1,1,221 | 1,1,221 |
P5 (Fig.
P6 (Fig.
Male. Total body length measured from tip of rostrum to posterior margin of caudal rami ranging from 289 µm to 460 µm (mean, 377 µm; n, 7; total body length of allotype, 415 µm).
Prosome: As in female.
Urosome (Fig.
Caudal rami (Fig.
Sexual dimorphism: Expressed in A1, P2 ENP, P5, and P6.
Antennule (Fig.
Antenna, mandible, maxillule, maxilla, and maxilliped: As in female.
P1: As in female.
P2: EXP (not shown) as in female. ENP (Fig.
P3 and P4: As in female.
P5 (Figs
P6 (Fig.
Variability. One intersexual specimen (ICML–EMUCOP-180119-10) possesses female antennules, displays genital double-somite (Fig.
The specific epithet from the Greek πρώτη, prṓtē, first, makes reference to the first species of Lonchoeidestenhelia gen. nov. described so far. Gender feminine.
Mexico, Sinaloa State: Urías estuary, stn 2, 23.1587°N, 106.3326°W, depth 1.8 m, organic carbon content 3.99%, organic matter content 6.86%, sand 80.42%, clay 8.29%, silt 11.28%.
Mexico, Sinaloa State: Urías estuary, stn 1: 23.15194°N, 106.3128°W, depth 1.5 m, organic carbon content 3.74%, organic matter content 6.43%, sand 25.31%, clay 35.75%, silt 38.94%, stn 4: 23.1840°N, 106.3579°W, depth 0.7 m, organic carbon content 1.13%, organic matter content 1.94%, sand 82.44%, clay 8.27%, silt 9.29%, stn 7: 23.2174°N, 106.3917°W, depth 3.7 m, organic carbon content 5.59%, organic matter content 9.62%, sand 10.78%, clay 37.54%, silt 51.68%, stn 9: 23.1904°N, 106.4121°W, depth 5.4 m, organic carbon content 1.41%, organic matter content 2.43%, sand 64.81%, clay 8.09%, silt 27.11%, and stn 10: 23.1815°N, 106.4214°W, depth 6.0 m, organic carbon content 1.2%, organic matter content 2.07%, sand 69.12%, clay 7.91%, silt 22.97%.
Willenstenhelia thalia Karanovic and Kim, 2014, by original designation.
Wi. minuta (A. Scott, 1902) (= D. minuta A. Scott, 1902), Wi. unisetosa (Wells, 1967) (= Stenhelia (Delavalia) unisetosa Wells, 1967), Wi. reducta sp. nov., Wi. urania Karanovic and Kim, 2014, and Wi. terpsichore Karanovic and Kim, 2014.
One female holotype (ICML–EMUCOP-180119-25) from the type locality and one male allotype (ICML–EMUCOP-180119-26) from stn 4; four (ICML–EMUCOP-180119-31) and one (ICML–EMUCOP-180119-32) female paratypes from the type locality; one female and one male paratype (ICML–EMUCOP-180119-33), one female paratype (ICML–EMUCOP-180119-34), and two female paratypes (ICML–EMUCOP-180119-35) from stn 4; one female and one male paratype (ICML–EMUCOP-180119-36), one female paratype (ICML–EMUCOP-180119-37), and one CIV, one CV, one female and two male paratypes (ICML–EMUCOP-180119-38) from stn 9; one CIII, one CIV, and two female paratypes (ICML–EMUCOP-180119-39) from stn 10; all preserved in alcohol. Two dissected female paratypes (ICML–EMUCOP-180119-27, ICML–EMUCOP-180119-28) mounted onto eight and six slides, respectively, and one dissected male paratype (ICML–EMUCOP-180119-29) mounted onto three slides, all from stn 2; one dissected male paratype (ICML–EMUCOP-180119-30) from stn 4 mounted onto eight slides. 18 Jan. 2019. S. Gómez leg.
Stenheliinae: Willenstenhelia. Female antennule eight-segmented. Armature formula of P4 EXP, 0,1,122. Female P5 baseoendopods not fused medially; endopodal lobe with two setae separated by wide gap, outer seta well-developed, inner seta minute; exopod with five setae, of which innermost as long as two outermost setae, middle seta smallest, inner neighboring seta longest. Male antennule ten-segmented. Male P5 EXP discrete, with four elements, of which apical a strong spine, two medial ones small and subequal in length, innermost smallest arising midway inner margin; baseoendopods fused medially forming a continuous plate, each endopodal lobe with one strong spine-like element fused to endopod, both elements set close to each other.
Female. Total body length measured from tip of rostrum to posterior margin of caudal rami ranging from 445 µm to 510 µm (mean, 477 µm; n, 3; total body length of holotype, 510 µm); habitus (Fig.
Prosome (Fig.
Urosome (Figs
First urosomite (fifth pedigerous somite): Visibly narrower than preceding somites in dorsal view (Fig.
Genital double-somite: Ca. 1.5× as wide as long, widest part at proximal half (Fig.
Fourth urosomite: With short spinular row and pore laterally on each side (Fig.
Fifth urosomite (Fig.
Anal somite (Figs
Caudal rami (Figs
Rostrum (Fig.
Antennule (Fig.
Antenna (Fig.
Mandible (Fig.
Maxillule (Fig.
Maxilla (Fig.
Maxilliped (Fig.
P1 (Fig.
P2 (Fig.
P3 (Fig.
P4 (Fig.
Setal formula of swimming legs as follows:
P1 | P2 | P3 | P4 | |
EXP | 0,1,022 | 0,1,123 | 0,1,223 | 0,1,122 |
ENP | 1,211 | 1,2,121 | 1,1,121 | 1,0,121 |
P5 (Fig.
P6 (Figs
Male. Total body length measured from tip of rostrum to posterior margin of caudal rami ranging from 251 µm to 363 µm (mean, 309 µm; n, 5; total body length of allotype, 363 µm).
Prosome: As in female.
Urosome: Largely as in female except for genital and third urosomites separated, and spinular ornamentation of fourth and fifth urosomites (Figs
Caudal rami (Figs
Sexual dimorphism: Expressed in A1, P2 ENP, P3, P4, P5, and P6.
Antennule (Fig.
Antenna, mandible, maxillule, maxilla, and maxilliped: As in female.
P1: As in female.
P2 (Fig.
P3 (Fig.
P4 (Fig.
P5 (Figs
P6 (Fig.
No variability was observed in the inspected material.
The specific epithet from the Latin reducta, reduced, in reference to the reduced inner seta on the female P5 baseoendopod, and to the reduced armature complement on the female and male P5 BENP. It is an adjective in the nominative singular; gender feminine.
Mexico, Sinaloa State: Urías estuary, stn 2: 23.1587°N, 106.3326°W, depth 1.8 m, organic carbon content 3.99%, organic matter content 6.86%, sand 80.42%, clay 8.29%, silt 11.28%.
Mexico, Sinaloa State: Urías estuary, stn 4: 23.1840°N, 106.3579°W, depth 0.7 m, organic carbon content 1.13%, organic matter content 1.94%, sand 82.44%, clay 8.27%, silt 9.29%, stn 9: 23.1904°N, 106.4121°W, depth 5.4 m, organic carbon content 1.41%, organic matter content 2.43%, sand 64.81%, clay 8.09%, silt 27.11%, stn 10: 23.1815°N, 106.4214°W, depth 6.0 m, organic carbon content 1.20%, organic matter content 2.07%, sand 69.12%, clay 7.91%, silt 22.97%.
In their paper,
Lonchoeidestenhelia gen. nov. shares the potentially synapomorphic loss of the inner seta on the P1 EXP2 (
Affinities of Willenstenhelia reducta sp. nov. The genus Delavalia is not only the most species-rich genus within the Stenheliinae, but also the most morphologically diverse. Although past decades have witnessed important advancements in the study of the genus, its monophyletic status is far from resolved (
Additionally, they (
Similarly,
To the best of my knowledge, the innermost seta of the pentasetose female P5 EXP displaced to the inner margin of the ramus is present only in Willenstenhelia, and its autapomorphic status for the genus in confirmed. Also, I could not find any other species, for which the male is known, with the outer spine of the male P4 EXP2 comparatively more sclerotized and longer than in the female, and curved inwards, and its autapomorphic status for Willenstenhelia is provisionally accepted. Some other species in other related genera, e.g., Wellstenhelia euterpe, display a reduced armature complement of the female P5 BENP from five to three setae, but Willenstenhelia is unique in the wide gap between the innermost element and its outer neighboring seta. This wide gap between the innermost element and its next outer neighboring seta is accepted here as autapomorphic for Willenstenhelia.
As with other stenheliins with a two-segmented P1 endopod, Wi. reducta sp. nov. was initially attributed to Delavalia. However, it was subsequently allocated into Willenstenhelia on account of (i) the pentasetose female P5 EXP in which the innermost seta is displaced to the inner margin, (ii) the reduced armature complement of the female P5 BENP, with two setae only, and with a wide gap between the innermost element and its outer neighboring seta, and (iii) presence of a sclerotized long and recurved outer spine on the male P4 EXP2.
The interspecific relationships amongst the species of Willenstenhelia are not clear. The Mexican Wi. reducta sp. nov. seems to belong to a core of species composed of Wi. minuta, Wi. urania, and Wi. terpsichore characterized by the strongly reduced inner seta of the female P5 baseoendopod. However, Wi. reducta sp. nov. is different from the other three species in the presence of one outer seta only on the discrete, not fused medially, baseoendopods of the female P5, i.e. Wi. reducta sp. nov. underwent loss of the outermost shorter seta of the female P5 baseoendopod which is still present in Wi. minuta, Wi. urania, and Wi. terpsichore, and unlike these three species, both baseoendopods of the female P5 of Wi. reducta sp. nov. are not fused medially. The loss of the outermost seta of the female P5 baseoendopod of Wi. reducta sp. nov. is regarded here as autapomorphic for the species. The innermost seta of the female P5 EXP and the outermost seta of the female P5 baseoendopod of Willenstenhelia thalia underwent reduction, but the innermost seta of the female P5 baseoendopod is visibly larger than in Wi. minuta, Wi. urania, and Wi. terpsichore. The reduction of the innermost seta of the female P5 EXP of Wi. thalia is considered here as autapomorphic for that species. Willenstenhelia unisetosa stands out for its three well-developed setae on the female P5 baseoendopod and for the discrete baseoendopods of the female P5 which are regarded here as the most plesiomorphic conditions. Willenstenhelia unisetosa and Wi. reducta sp. nov. share the discrete baseoendopods of the female P5. The male is known only for Wi. thalia, Wi. terpsichore, Wi. unisetosa and Wi. reducta sp. nov. Willenstenhelia reducta sp. nov. shares the male P5 EXP with three small inner setae and the discrete apical spine with Wi. unisetosa, but it also shares the endopodal spines fused to the baseoendopod with Wi. terpsichore. The most plesiomorphic condition seems to be that of Wi. thalia with two (or three?) inner setae on the male P5 baseoendopod, and the inner medial seta of the exopod well-developed.
I am deeply indebted to Abraham Guerrero Ruíz (Centro de Investigación en Alimentación y Desarrollo, Unidad Mazatlán) and to Sergio Rendón Rodríguez (Instituto de Ciencias del Mar y Limnología, Unidad Académica Mazatlán) for their help during the sampling campaigns Thanks also goes to Nataly Ortíz Gálvez and Ángel A. Valenzuela Cruz for their help during the sampling campaigns and for processing the sediment samples. I wish to express my gratitude to Dr. Paulo H. Costa Corgosinho and to Dr. Kai Horst George for their comments to the first draft of the manuscript. This is a contribution to project IN202019 Biodiversidad de la meiofauna en un ecosistema costero contaminado del sur de Sinaloa: un enfoque integrativo de técnicas taxonómicas clásicas y moleculares financed by the Programa de Apoyo a Proyectos de Investigación e Innovación Tecnológica (DGAPA-PAPIIT) of the Universidad Nacional Autónoma de México.