Research Article |
Corresponding author: Cristian Aldea ( cristian.aldea@umag.cl ) Academic editor: Charles Oliver Coleman
© 2015 Patricia Esquete, Cristian Aldea.
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:
Esquete P, Aldea C (2015) Leucothoe kawesqari, a new amphipod from Bernardo O’Higgins National Park (Chile), with remarks on the genus in the Magellan Region (Crustacea, Peracarida). ZooKeys 539: 83-95. https://doi.org/10.3897/zookeys.539.6157
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Although the genus Leucothoe has been reported repeatedly in the Magellan Region, the citations in the Channels and Fjords Ecoregion were either unidentified or attributed to the previously considered cosmopolitan Leucothoe spinicarpa. In this work, Leucothoe kawesqari sp. n. is described, which can be distinguished from other species of the genus in the Southern Ocean by having eyes present, epimeral plates with no setae, anterior coxae not acutely produced or excavate, coxa 5 slightly bilobed, accessory flagellum present, mandibular palp article 3 shorter than ½ article 2, pereopods 5–7 basis expanded, ovoid, posterior margin weakly crenulate and telson apex irregularly truncated. The new species was found in hard substrates, both unvegetated and with macroalgae, mainly in kelp forest of Macrocystis pyrifera.
A pesar de que el género Leucothoe ha sido citado en la región Magallánica en repetidas ocasiones, las citas en la Ecorregión de Canales y Fiordos o bien no han sido identificados o atribuidos a la antes considerada especie cosmopolita L. spinicarpa. En este trabajo se describe L. kawesqari sp. n., que se distingue de otras especies del género que se encuentran en el Océano Antártico por presentar ojos, placas epimerales sin setas, coxas anteriores no puntiagudas ni excavadas, coxa 5 ligeramente bilobulada, flagelo accesorio, artículo 3 del palpo mandibular más corto que la mitad del artículo 2, bases de los pereiópodos 2–7 expandidas con el margen ligeramente crenulado y ápice del telson truncado e irregular. La nueva especie fue encontrada en sustratos duros, tanto sin vegetación como con macroalgas, dominadas por bosques de huiros de la especie Macrocystis pyrifera.
Pacific Ocean, channels and fjords, Southern Ocean, benthos, Macrocystis pyrifera
Océano Pacífico, Canales y Fiordos, Océano Antártico, bentos, Macrocystis pyrifera
Leucothoe Leach, 1814 is a speciose amphipod genus that currently comprises 132 species (
The genus Leucothoe has been reported repeatedly in the Magellan Region, defined as the Patagonian shelf south of about 41°S on both the Pacific and Atlantic sides, assigned to the wrongly considered cosmopolitan species Leucothoe spinicarpa (Abildgaard, 1789) (see
BONP is placed in the Chilean geopolitical regions of Aysén and Magallanes, between 48.0–51.6°S and 73.3–75.8°W (
Between January and March 2010 two cruises were carried out onboard the vessel MV Nueva Galicia with the objective of sampling the rocky sublittoral bottoms of the channels and fjords of BONP. A total of 23 sites was sampled with SCUBA: five samples were taken manually at both 5 and 15 m depth at each site (10 samples at each site), harvesting squares of 25×25 cm (0.063 m2) by scraping off all the organisms (including fauna and smaller algae), but not the kelps. Samples were fixed in 5% buffered formalin and subsequently sorted, preserved in 70% alcohol and identified. Illustrations were performed using a camera lucida connected to a compound microscope.
Terminology used in the description follows
Holotype: female, 8 mm length, MNHNCL AMP-15038; Paratypes: female, dissected, 5 mm length, MNHNCL AMP-15039; 2 females,
Head anterior margin rounded, mid-cephalic keel quadrate but not prominent. Eyes present. Epimeral plates with no setae, epimeron 3 posterior margin excavate, postero-ventral corner blunt, with right angle. Coxae 1-3 not acutely produced, nor excavated, coxa 3 longer than broad, coxa 5 slightly bilobed. Antenna 1 main flagellum of 11–12 articles, accessory flagellum present, minute, of two unequal segments. Antenna 2 flagellum of 6 articles. Mandibular palp article 3 shorter than ½ of article 2. Ganthopod 1 propodus palm with minute serrations. Dactylus reaching 0.4 of propodus length. Gnathopod 2 basis posterior margin smooth, carpus smooth, without tooth or process, setose, reaching 0.3 of propodus length, propodus with short, blunt distal prolongation and three medial rows of setae. Pereopods 5–7 bases expanded, ovoid, posterior margin weakly crenulate. Telson apex irregularly truncated.
Named after the Alacalufe people Kawésqar, whose ancestral territory extends through the Magellan Region, from the Gulf of Penas to the Strait of Magellan.
Description.
Body (Fig.
Head (Fig.
Antenna 1 (Fig.
Antenna 2 (Fig.
Mouthparts. Upper lip (Fig.
Gnathopod 1 (Fig.
Gnathopod 2 (Fig.
Pereopod 3 (Fig.
Pereopod 4 (Fig.
Pereopod 5 (Fig.
Pereopod 6 (Fig.
Pereopod 7 (Fig.
Epimeral plates (Fig.
Uropods. Uropod 1 (Fig.
Telson (Fig.
As mentioned above, the only described species of Leucothoe found in the Magellan Region is L. weddellensis. Following
L. kawesqari is most similar to Leucothoe antarctica Pfeffer, 1888 as redescribed by
Regarding other species from the Southern Ocean, Leucothoe merletta Krapp-Schickel & De Broyer, 2014 can be readily differentiated from L. kawesqari because of having coxae 2 and 4 with acute anterodistal angles, having mandibular palp article 3 about as long as article 2, pereopods 5–7 basis with regularly rounded hind margin, epimeron 1 distal margin rounded and epimeron 3 with rectangular posterodistal corner. Leucothoe campbelli Krapp-Schickel & De Broyer, 2014 has a longer mandibular palp article 3 (1/2 length of article 2), coxa 3 subtrapezoidal, gnathopod 1 propodus more robust, pereopods 5–7 basis posterior margin smoth and epimeral plate with posterodistally upturned corner. Leucothoe longimembris Krapp-Schickel & De Broyer, 2014 lacks eyes, no accessory flagellum, mandibular palp article 3 1/2 length of article 2, and basis of pereopods 5–7 slim, broadest proximally. Leucothoe macquariae Krapp-Schickel & De Broyer, 2014 lacks accessory flagellum, mandibular palp article 3 1/2 length of article 2, more robust gnathopods carpi, epimeron 3 distal posterior margin distal corner blunt and upturned, and telson tip acute. Leucothoe orkneyi Holman & Watling, 1983 can be immediately differentiated in having a very slender gnathopod 1 propodus, and having a very prominent mid-cephalic keel, no accessory flagellum, a very slender, pereopods 5–7 basis margin strongly serrated, and epimera distal margins with setae.
Leucothoe tolkieni Vinogradov, 1990 is the only other species described from the Southeastern Pacific, although it was found well offshore. It differs from the species described here mainly in having the head anterior margin truncate with eyes that cover most of the head, gnathopod 1 basis anteroproximally expanded, and propodus curved, proximally inflated, gnathopod 2 carpus distally truncate, spoon-like, pereopods 5–7 bases narrowly expanded and telson apex rounded.
Although previous reports of L. spinicarpa in the Magellan Region are probably wrong (
Leucothoe kawesqari was one of the dominant species of amphipod found in unvegetated hard substrates in the southernmost sampling site, where the amphipods Polycheria antarctica (Stebbing, 1875) and Orchestia spp., were also abundant. Towards the north of BONP, L. kawesqari was found in subtrates dominated by kelp forest of Macrocystis pyrifera, where Andaniopsis integripes (Bellan-Santini & Ledoyer, 1986) was dominant and it also co-occurred with the tanaid Zeuxoides troncosoi Esquete & Bamber, 2012 and juveniles of the isopod family Janiridae. High abundances of other benthic taxa were found co-occurring with L. kawesqari: the polychaetes Platynereis australis (Schmarda, 1861) and Perinereis gualpensis Jeldes, 1963, the bivalve Aulacomya atra (Molina, 1782) the decapod Halicarcinus planatus (Fabricius, 1775) and unidentified species of Echinodermata (Ophiuroidea and Psolidae), Porifera and Ascidiacea. These specimens of L. kawesqari were likely associated with or endocommensal associates of the Porifera and Ascidacea specimens withinin the sample, since the sampling method (scraping substrate) dislodges the samples and everything was sorted through at one time (
The two species currently described for the Magellan Region have a well separated geographical distribution (Fig.
The geographical distribution of the species of Leucothoe studied by
We would like to thank our colleagues who supported us collecting samples used in this study and the crew of MV Nueva Galicia for their assistance. To Jesús Troncoso (Universidad de Vigo, Spain) and Carlos Ríos (Instituto de la Patagonia, Universidad de Magallanes, Chile) we thank for aiding us in technical facilities. This work was carried out starting from the project INNOVA 08CTU01-20, which was developed by CEQUA Foundation and Chilean National Forest Corporation (CONAF), and supported by the Chilean Production Development Corporation (CORFO). P. Esquete was supported by postdoctoral grant SFRH/BPD/94985/2013 awarded by the Fundacão para a Ciência e Tecnologia (FCT, Portugal). The authors also thank Kristine White and an anonymous reviewer for their contribution in improving the manuscript.