Research Article |
Corresponding author: Regina Wetzer ( rwetzer@nhm.org ) Academic editor: Tammy Horton
© 2017 Regina Wetzer, Gracie Mowery.
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:
Wetzer R, Mowery G (2017) Redescription of Dynoides elegans (Boone, 1923) (Crustacea, Isopoda, Sphaeromatidae) from the north-eastern Pacific. ZooKeys 646: 1-16. https://doi.org/10.3897/zookeys.646.10626
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Dynoides elegans (Boone, 1923) from southern California is reviewed, redescribed, and figured. The original species description did not include figures, making it difficult to attribute individuals to the species. Dynoides saldanai Carvacho and Haasmann, 1984 and D. crenulatus Carvacho & Haasman, 1984 from the Pacific Coast of Mexico and D. brevicornis Kussakin & Malyutina, 1987, from Furugelm Island, Peter the Great Gulf in the Sea of Japan, appear morphologically more similar to each other than to western Pacific species. A large pleonal process is present in about half of the Dynoides species, but is absent in this north-eastern Pacific clade and the north-western Pacific D. brevicornis and D. brevispina. Dynoides dentisinus Shen, 1929 possess a large pleonal spine. It is known from China, Japan, and Korea and is introduced in San Francisco Bay; it can be easily distinguished from D. elegans by the presence of a pleonal process in the former. A key to the Pacific West Coast Dynoides is provided.
Isopoda , Sphaeromatidae , Dynoides , California, East Pacific, intertidal
The genus Dynoides Barnard, 1914 was erected for D. serratisinus Barnard, 1914 from Natal and Mozambique (
Pearl Lee Boone described several new isopod genera and species from the California coast in her 1923 paper, all without figures. She erected the new genus Clianella Boone, 1923 for C. elegans from La Jolla, California based on six specimens collected in 1915 “from bunches of mussels along the outer ledge of rocks north of Scripps Institution of Biological Research.” Of these she designated a male holotype and two male paratypes which are part of the United States National Museum of Natural History collections (Cat. Nos. 50421 and 1422085) and which were examined here. The other three paratypes were donated to the Scripps Institution of Biological Research (
The individual designated by Boone as the holotype has previously had pleopods 1–4 removed. Some pleopods were recovered floating in the vial containing the specimen. One paratype had several broken pereopods, and its dorsum is cracked. The second paratype was complete and in as good a condition as can be expected of a 97-year-old specimen. Permission was granted for dissection and this individual is figured here.
The composition of Dynoides and its relationship to Clianella was reviewed by
Descriptions are based on the male paratype and additional material as noted. Specimens examined have
Specimens are prepared for SEM as described in
Molecular data were generated for this species according to the protocols described in
This key is based on adult ♂ characters. Also note that weak pereon tubercles are visible only with SEM and not necessarily evident with light microscopy.
1 | Pleon with elongate dorsal process, produced into prominent, triangular, posteriorly pointed, conical process, extending to anterior margin of the teardrop-shaped pleotelsonic slit; pleotelsonic slit with strong crenulate margins | Dynoides dentisinus |
– | Pleon without triangular, posteriorly pointed, conical process; pleotelsonic slit teardrop- or heart-shaped; pleotelsonic slit without or with only weak crenulate margins | 2 |
2 | Pleon without broad shelf-like ridge. Pleotelson in form of bilobed dome. Pleotelsonic slit with parallel sides; base of slit teardrop-shaped | Dynoides crenulatus |
– | Pleon with broad shelf-like ridge. Pleotelson vaulted, without bilobed dome. Pleotelsonic slit elongated teardrop- to completely heart-shaped. Base of pleotelsonic slit with prominent tubercle barely overlapping base of slit | 3 |
3 | Pleotelsonic slit heart-shaped, without crenulate slit margins. Antennule with 9 flagellar articles, only 7 distalmost articles with aesthetascs. Antenna article 5 length 1.4 × width. Penes distal apex distinctly acute; basal half fused; apex pitch fork-shaped. Pleopod 3 exopod with suture | Dynoides saldanai |
– | Pleotelsonic slit elongated teardrop- to heart-shaped, slit with weak crenulate margins. Antennule with 14 or more flagellar articles, only 12 distalmost articles with aethetascs. Antenna article 5 length 2.2 × width. Penes distal apex rounded and blunt; basal third fused; apex tuning fork-shaped. Pleopod 3 exopod without suture | Dynoides elegans |
Dynoides serratisinus Barnard, 1914: 408; from South Africa by monotypy.
A diagnosis and comprehensive synonymy was provided by
Clianella
elegans
Boone, 1923: 153;
Dynoides
elegans
.
HOLOTYPE ♂ (7.04 mm), California, San Diego County, La Jolla, Scripps Institution for Biological Research, ~32.27°N ~117.61°W, 23 Oct 1915,
2 ♂ PARATYPES (6.03, 5.36 mm, smaller specimen dissected and figured), same data as holotype,
Non-type material: 1 ♂ (6.16 mm), California, Los Angeles County, White Point, San Pedro, ~33.715°N ~118.314°W, 18 May 1919. Coll. E.P. Chace,
2 ♂ (largest ♂ 5.36 mm, 2nd male used for SEM), plus 8 non-gravid females, subadults and juveniles, California, Los Angeles County, Palos Verdes Peninsula, Pt. Fermin, shore at Paseo del Mar, ~0.5 mi. W of Gaffey Street, 33.71°N 118.30°W, mid-low intertidal, chipping overhanging rock with hammer and Phragmatopoma tubes on underside of rock, 0.99 m. Fixed and preserved in 95% ethanol. 27 Mar 2004. Sta. #2. Coll. R. Wetzer, N.D. Pentcheff, and LMU students. RW04.030.
1 male (5.36 mm), 3 ?females/subadults, 13 juv., Pt. Fermin, shore at Paseo del Mar, ~0.5 mi. W of Gaffey Street, eastern end of beach, ~33.71°N ~118.3°W, mid intertidal, scraping live barnacles off deeply crenulated rock shelf, fixed and preserved in 95% ethanol. 13 Jun 2006. Coll. R. Wetzer. RW06.063.
1 male (5.35 mm), 5 subadults, 2 juv., Los Angeles County, Santa Catalina Island, Big Fisherman Cove, in front of
2 subadult males (largest individual 5.4 mm), 2 juvenile specimens, and posterior half of a gravid female, Santa Catalina Island, Avalon Harbor, ~33.35°N ~118.33°W, either rock or artificial substrate, subtidal scrapings, 3.05 m. Probably fixed in formalin, stored in 95% ethanol. 1 May 2011. Sta. 406. Coll. LACSD, rcvd. from D. Cadien. RW12.212.
9 specimens (largest 7.37 mm), Santa Barbara County, Santa Cruz Island, Pelican Bay, ~34.035°N ~119.703°W, under Mytilus beds, 18 Jul 1939. Coll. W.G. Hewatt. RW16.019.
1 male (6.83 mm), Pacific, Mexico, Baja California Norte, Cedros Island, South Bay, Sta. 288-34, 10 May 1934. RW16.028.
2 specimens (3.9 mm and 4.0 mm) photographed live, Los Angeles County, San Pedro, White Point, 33.72°N 118.32°W, rocky intertidal, hand, preserved in 95% ethanol. 23 Jun 2016. Coll. A. Wall, J. Wall, K. Omura, N.D. Pentcheff, L. Harris. RW16.051.
Body length 2.4 × width; pereonites 1–5 smooth, pereonite 1 medially very slightly raised, pereonites 6–7 with very small tubercles; pleotelson covered with small tubercles; pleotelson length 1.2 × width, anterior of pleotelsonic sinus with prominent rounded tubercle barely overhanging base of sinus, sinus walls straight-sided, finely crenulate, and slightly raised. Coxal margins with setae appearing membranous, membrana cingula, (Figures
Antennula peduncle article 1 length 3.6 × width, anterior medial margin with 2 palm setae; article 2 as long as wide, inferior distal margin with 1 palm seta, superior margin with 1 palm seta; article 3 length 2.2 × width, proximal margin with 1 simple seta; flagellum with 14 articles, 12 distalmost articles with aesthetascs (Figure
Left mandible incisor with 3 cusps; lacinia mobilis with 3 cusps; lacinia mobilis spine row comprised of 2 serrate and 3 simple spines; crushing surfaces strongly ridged; mandibular palp article 1 with 2 minute setae; article 2 with 2 palm setae and 2 plumose setae; article 3 with long, plumose setae (Figure
Pereopods 1–7 (Figures
Penial process length 2.3 × basal width, basal third fused (Figure
Pleopod 1 peduncle length 2.3 × width with 2 coupling hooks (Figure
Uropod exopod proximolateral margin rolled, weakening distally; in the adult ♂ holotype (
Body length 2.2 × width; (Figures
Size. Largest ♂ to 7.37 mm, largest ♀ to 5.4 mm.
Color. When alive brightly colored, individuals highly varied (Figure
California: San Diego to Santa Barbara Counties.
Both 18S-rDNA and 16S-rDNA were generated from the same individual from Pt. Fermin (RW04.030), GenBank numbers JF699541, and KU248214, respectively. Locality information is provided above in Material Examined. This specimen came from the same lot from which the SEM specimen in Figure
Dynoides elegans is morphologically most similar to D. saldanai and D. crenulatus (Pacific, Mexico, Oaxaca). These three species are easily distinguished from Dynoides dentisinus. Adult male specimens of Dynoides dentisinus are more robust than those of D. elegans and have a distinctive, prominent large process extending over the pleotelson (Figure
Dynoides dentisinus. ♂, A dorsal B lateral C ventral. California, Alameda County, San Francisco Bay, off Doolittle Road near Oakland Airport, 37.73°N 122.21°W, from low intertidal under rocks, associated with sponge, salinity 30 ppt, fixed and preserved in 95% ethanol. 5 Jun 2002. Coll. R. Wetzer, T. Haney, and S. Boyce. RW02.027. MBPC 17838.
A generic description of the “penes fused along proximal half of length” (
Dynoides elegans is most similar to the Oaxacan species, D. saldanai. They share pleonal characters which are known to change as individuals, especially males, mature. Penial processes, pleonal process, appendix masculina, pleotelson morphology and also pleotelson sinus morphology are characters that all change with age in males. A fully adult male (penes and appendix masculina developed) may not be at the final fully developed male stage, potentially with some further changes to the pleotelson morphology. We do know that in males the sinus will transition progressively from a simple slit to a quite complex structure. The body length of the D. elegans type specimens range from 5.36 to 7.04 mm. The subtle changes in morphology are readily observed in Figure
The figured male paratype (Figure
Dynoides elegans is known from San Diego County to Santa Barbara County, with a single male specimen (
We thank the
This is Contribution Number 1 of the NHM Diversity Initiative for the Southern California Ocean (DISCO).