Research Article |
Corresponding author: Jeffrey G. Baguley ( baguley@unr.edu ) Academic editor: Danielle Defaye
© 2015 Hyun Woo Bang, Jeffrey G. Baguley, Heejin Moon.
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:
Bang HВ, Baguley JГ, Moon H (2015) First record of harpacticoid copepods from Lake Tahoe, United States: two new species of Attheyella (Harpacticoida, Canthocamptidae). ZooKeys 479: 1-24. https://doi.org/10.3897/zookeys.479.8673
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Benthic harpacticoids were collected for the first time at Lake Tahoe, California-Nevada, United States. Two species were identified as members of the genus Attheyella Brady, 1880. The genus Attheyella comprises about 150 species within six subgenera, but only twelve species have previously been reported from North American freshwater habitats. The two new species of Attheyella described here have a 3-segmented endopod on P1 and 2-segmented P2–P4 endopods, the distal segment of exopod of P2–P4 has three outer spines, and the P5 has five setae on the exopod and six setae on the baseoendopod. Attheyella (Attheyella) tahoensissp. n. most closely resembles A. (A.) idahoensis (Marsh, 1903) from Idaho, Montana, and Alaska (United States) and A. (A.) namkungi Kim, Soh & Lee, 2005 from Gosu Cave in South Korea. They differ mainly by the number of setae on the distal endopodal segment of P2–P4. In addition, intraspecific variation has been observed on the caudal rami. Attheyella (Neomrazekiella) tessiaesp. n. is characterized by the extension of P5 baseoendopod, 2-segmented endopod of female P2–P3, and naked third seta of male P5 exopod. The two new species are likely endemic to Lake Tahoe, an isolated alpine lake within the Great Basin watershed in the western United States.
Benthic Harpacticoida, Canthocamptidae , Lake Tahoe, Nevada, California
Lake Tahoe is a large freshwater lake in the Sierra Nevada of the United States. At a surface elevation of 1,897 m, it is located along the border between California and Nevada. Lake Tahoe is the largest alpine lake in North America. Its depth is 501 m, making it the deepest in the United States after Crater Lake (593 m). Lake Tahoe is one of the largest lakes by volume (1.5 × 1011 m3) in the United States, only being exceeded by the Great Lakes. While, some basic ecological investigations have occurred in Lake Tahoe (
During the past century, fresh water harpacticoid copepods in North America have been reported by several researchers, with checklists provided by: Wilson CB (
Considering all studies of North American harpacticoid copepods, Canthocamptidae is the most abundant harpacticoid family on the continent (
The genus Attheyella Brady, 1880 has been found in a wide range over the world (
As part of ongoing efforts to understand the ecological role of meiobenthos in Lake Tahoe, harpacticoid copepods have been collected and documented here for the first time. Here, two new species of Attheyella from the Lakeside Beach littoral zone are described and an updated key to species of Attheyella in North America is provided.
Samples were collected from the Lakeside Beach littoral zone, 5 m water depth, on south shore of Lake Tahoe near the California-Nevada border in July 2013. Sediment samples were collected manually by SCUBA divers. Sediments were sampled with 2.9 cm inner diameter core tubes and were fixed with 70% ethanol and stained with Rose Bengal. Meiofauna was extracted from sediments by Ludox isopycnic centrifugation (
Specimens were dissected in lactic acid and the dissected parts were mounted on slides in lactophenol mounting medium. Preparations were sealed with transparent nail varnish. All drawings have been prepared using a camera lucida on a Leica DM 2500 differential interference contrast microscope. Specimens were deposited at the Smithsonian National Museum of Natural History.
The descriptive terminology is adopted from
The Lakeside littoral zone; 38°57'42"N, 119°57'14"W, 5 m water depth, of Lake Tahoe in California-Nevada, United States.
Holotype: 1♀ (USNM No: 1251801) dissected on 8 slides. Paratype 2♀♀ and 1♂ (USNM No’s listed in order presented in text: 1251802, 1251804, 1251803) each dissected on 6, 9 and 8 slides respectively, and 6♀♀ and 4♂♂ (USNM No’s for specimens in vials (female, male): 1251805, 1251806) in 70% ethanol, vial. All from the type locality, July 2013, leg. J.G. Baguley.
Female. Total body length 816 µm (n=6; range: 753-868 µm), measured from anterior margin of rostrum to posterior margin of caudal rami. Largest width measured at posterior margin of cephalic shield: 241 µm. Urosome narrower than prosome (Fig.
Cephalothorax (Fig.
Genital somite and first abdominal somite partly fused forming double-somite, wider than long. Genital field as in Fig.
Anal somite (Figs
Antennule (Fig.
Antenna (Fig.
Mandible (Fig.
Maxillule (Fig.
Maxilla (Fig.
Maxilliped (Fig.
Swimming legs 1-4 with wide intercoxal sclerite, biramous, endopods 2-segmented except for P1, exopods 3-segmented. Coxa and basis with row of spinules along outer margins as illustrated.
P1 (Fig.
P2–P4. Coxa and basis with spinular rows along outer margin and anterior surface. Basis with pinnate spine (P2) or bare seta (P3–P4), each seta arising from a setophore.
P2 (Fig.
P3 (Fig.
P4 (Fig.
Exopod | Endopod | |
---|---|---|
P1 | 0.1.022 | 1.1.120 |
P2 | 0.1.123 | 1.120 |
P3 | 0.1.223 | 1.230 |
P4 | 0.1.223 | 0.030 |
P5 (Fig.
P6 (Fig.
Male. Body slightly smaller and more slender than female, habitus as in Fig.
Prosome (Fig.
Urosome (Fig.
Caudal rami (Fig.
Antennule (Fig.
P3 (Fig.
P4 (Fig.
Fifth pair of legs (P5) (Fig.
P6 (Fig.
Intraspecific variability was observed in the shape of caudal rami of female (about 20%; 6/30 observed individuals). Caudal rami (Fig.
The species name refers to the type locality, Lake Tahoe. This is one of the largest alpine lakes in the world is known for its pristine waters and aesthetic beauty.
The Lakeside littoral zone; 38°57'42"N, 119°57'14"W, 5 m water depth, of Lake Tahoe in California-Nevada, United States.
Holotype: 1♀ (USNM No: 1251796) dissected on 9 slides, from the type locality. Paratype 1♀ and 1♂ (USNM No’s listed in order presented in text: 1251797, 1251798) each dissected on 3 and 9 slides respectively, and 10♀♀ and 6♂♂ (USNM No’s for specimens in vials (female, male): 1251799, 1251800) in 70% ethanol, vial. Additional samples were deposited in the first author’s collection. All from the type locality, July 2013, leg. J. G. Baguley.
Female. Total body length 660 µm (n=5; range: 635–694 µm), measured from anterior margin of rostrum to posterior margin of caudal rami. Largest width measured at posterior margin of cephalic shield: 176 µm. Urosome narrower than prosome (Fig.
Cephalothorax (Fig.
Prosome with smooth posterior margins, pleural areas well developed. Body slightly constricted between each somite. All pedigerous somites with plain hyaline frill on posterior margin. Urosome 5-segmented, comprising P5-bearing somite, genital double-somite and 3 free abdominal somites.
Genital double-somite as wide as long. Original segmentation marked by discontinuous internal chitinous rib laterally, completely fused ventrally. A row of spinules present on lateral side of genital field. Genital field located far anteriorly (Fig.
Anal somite (Fig.
Antennule (Fig.
Antenna, mandible, maxillule, maxilla, and maxilliped as in A. (A.) tahoensis sp. n.
P1 (Fig.
P2 (Fig.
P3 (Fig.
P4 (Fig.
Exopod | Endopod | |
---|---|---|
P1 | 0.0.022 | 1.1.120 |
P2 | 0.1.123 | 1.121 |
P3 | 0.1.223 | 1.220 |
P4 | 0.1.223 | 0.230 |
P5 (Fig.
Male (Fig.
Cephalothorax (Fig.
Antennule (Fig.
P3 (Fig.
P4 (Fig.
Fifth pair of legs (P5) (Fig.
P6 (Fig.
The species name refers to Tahoe Tessie, a cryptozoological creature which supposedly resides in Lake Tahoe. While some claim to have seen the mythical Tahoe Tessie, none until now have seen these non-mythical microscopic creatures of the sand.
The family Canthocamptidae is the largest family of Harpacticoida found in freshwater habitats, and can be found in rivers, streams, ponds, lakes, and wetland, and even in hot springs, glacial melt water and damp moss (
The genus Attheyella Brady, 1880 is a genus of Canthocamptidae, and is cosmopolitan in distribution at the generic level (
Both new species are placed in the genus Attheyella because of the following diagnostic features: small rostrum, P1 with 3-segmented rami, 2-segmented endopod of P2–P3 in female, and 3-segmented P3 in males.
In
Attheyella (Attheyella) tahoensis sp. n. clearly belongs to the subgenus Attheyella given the elongate exopod and baseoendopod of P5, about equally wide, baseoendopod reaching near the end of exopod in female, and male P3 exopod-2 with enlarged outer spine reaching to end of exopod. Attheyella (A.) tahoensis sp. n. is closely related to the North American A. (A.) idahoensis (Marsh, 1903) and A. (A.) namkungi Kim, Soh and Lee, 2005 from South Korea, with seta formula of the female P4 exopod, and concave shape of caudal rami without a process. However, A. (A.) tahoensis sp. n. can readily be distinguished from its congeners by the number of setae on P2–P4. A. (A.) idahoensis has 4, 5 and 3 setae on distal segment of P2–P4 endopod, whereas A. (A.) tahoensis sp. n. has 3, 4 and 5 setae, respectively. Additionally, A. (A.) namkungi has 3, 4 and 2 setae on the distal endopod of P2–P4.
Morphological variation and abnormality are common in harpacticoid copepods. In the present study, intraspecific variation of A. (A.) tahoensis sp. n. has been recorded, with some specimens having variations on the shape and armature of the caudal rami (about 20% of total observed specimens). In the most commonly observed condition, caudal rami are about 2.5 times as long as wide, bottle-shaped, strongly tapering distally. In the less common morphological variant, caudal rami are about twice as long as wide, laterally compressed, with the inner margin of each ramus having lateral concavity.
In numerous instances, the morphological variation or deformity occurred due to environmental factors such as water pollution. However, some studies suggest that variation in caudal rami may be caused by interspecific competition. For example,
Attheyella (Neomrazekiella) tessiae sp. n. is placed in the subgenus Neomrazekiella on account of the following combination of characters: prosome with smooth posterior margins, female P5 endopodal lobe triangular, basal expansion wider than exopod, with six setae, male P5 not produced into narrow prolongation, P3 spine of exopod 2 not greatly enlarged in male. A. (N.) tessiae sp. n. can be clearly distinguished from other members of the subgenus Neomrazekiella by the 2-segmented endopods of female P2–P3, P5 baseoendopod produced to middle of exopod segment in female, and naked third seta of the male P5 exopod.
This investigation marks the first record of meiobenthos, and more specifically, of harpacticoid copepods, in Lake Tahoe. The newly described A. (A.) tahoensis sp. n. and A. (N.) tessiae sp. n. are likely endemic to Lake Tahoe. A total of 10 endemic macrobenthos have previously been identified in Lake Tahoe (summarized by
Together with newly described A. (A.) tahoensis sp. n. and A. (N.) tessiae sp. n., the three subgenera and fourteen species currently recognized as valid in the genus Attheyella from North America can be identified with the specific key given below. It is amended from
1 | Female P5 both exopod and baseoendopod elongate, of nearly same width, baseoendopod reaching nearly to end of exopod | subgenus Attheyella... 2 |
– | Female P5 baseoendopod much wider than exopod | 5 |
2 | Caudal ramus inner margin smoothly tapering or concave, without a process | 3 |
– | Female caudal ramus with prominent, acute, haired inner process; male caudal ramus with smaller, smooth inner process | A. (A.) obatogamensis (Willey, 1925) |
3 | Caudal ramus narrowed distally, the apex truncate | 4 |
– | Caudal ramus hardly at all narrowed distally, the apex rounded | A. (A.) alaskaensis M.S. Wilson, 1958 |
4 | Female antennule 8-segmented, P2–P4 endopod-2 with 4, 5, and 3 setae, respectively | A. (A.) idahoensis (Marsh, 1903) |
– | Female antennule 7-segmented, P2–P4 endopod-2 with 3, 4, and 5 setae, respectively | A. (A.) tahoensis sp. n. |
5 | Female P5 baseoendopod with 3 to 5 setae; caudal rami of both sexes similar, and body segments coarsely serrate | subgenus Ryloviella... 6 |
– | Female P5 baseoendopod with 6 setae; caudal rami of both sexes different, and body segments weakly serrate or smooth | subgenus Neomrazekiella... 8 |
6 | All or most setae on P1 - P5 slender | 7 |
– | Setae on P1 - P5 short, stout, spiniform | A. (R.) spinipes Reid, 1987 |
7 | P5 exopod about 2 times as long as wide; female P5 baseoendopod with 3 or 4 setae; caudal ramus with 2 or more longitudinal rows of spinules | A. (R.) carolinensis Chappuis, 1932 |
– | P5 exopod about 1.5 times as long as wide; female P5 baseoendopod with 5 (rarely 4) setae; caudal ramus with 2 or 3 oblique inner rows of hairs | A. (R.) pilosa Chappuis, 1929 |
8 | Female P2–P3 endopods usually 3-segmented; female P5 endopodal lobe produced to middle of exopod segment or beyond; male P5 exopod seta 3 naked, more slender than other setae | 9 |
– | Female P2–P3 endopods usually 2-segmented; female P5 endopodal lobe hardly at all produced; male P5 exopod seta 3 usually similar to other setae | 10 |
– | Female P2–P3 endopods 2-segmented; female P5 endopodal lobe reaching distal margin of exopod; male P5 exopod seta 3 naked | A. (N.) tessiae sp. n. |
9 | Female caudal ramus, distal half of outer margin strongly constricted, and outer apical seta outbent at base; male P4 exp3 outer distal and apical spines strongly curved | A. (N.) nordenskioldii (Lilljeborg, 1902) |
– | Female caudal ramus, outer margin evenly rounded, and base of outer apical seta straight; male P4 exp3 outer distal and apical spines straight | A. (N.) illinoisensis (S. A. Forbes, 1876) |
10 | Caudal ramus, lateral setae inserted next to each other | 11 |
– | Caudal ramus, insertions of lateral setae well separated | 12 |
11 | Female P5 baseoendopod with 6 normal setae; caudal ramus, outer distal corner with rounded sclerotized flange overlying bases of apical setae | A. (N.) dogieli (Rylov, 1923) |
– | P5 baseoendopod with 6 slender spiniform setae, all of them completely fused with baseoendopod; caudal ramus, outer distal corner with only a few spinules | A. (N.) ussuriensis Rylov, 1933 |
12 | Caudal ramus about as long as anal somite, smoothly tapering, dorsal surface with prominent subquadrate or crescentic sclerotization distal to dorsal seta | A. (N.) dentata (Poggenpol, 1874) |
– | Caudal ramus about 1/2 length of anal somite, outer distal margin constricted, dorsal surface with no special structure | A. (N.) americana (Herrick, 1884) |
This research was supported in part by a grant from the Sagebrush Chapter of Trout Unlimited. Jared Northon provided vessel support for field sampling activities. Jared Northon, Paul Bennetts, and Barrett Welch assisted with field sampling. Undergraduate assistants Karmen Swanson, Brie Cordier, and Kira Espinosa-Levy sorted specimens as part of our larger efforts to understand meiobenthic community structure in Lake Tahoe. Samples were collected in collaboration with Dr. Sudeep Chandra and Andrea Caires who have greatly helped facilitate our meiobenthic research efforts in Lake Tahoe.