Records of the Australian Museum (2020) Records of the Australian Museum vol. 72, issue no. 2, pp. 45–62 a peer-reviewed open-access journal https://doi.org/10.3853/j.2201-4349.72.2020.1764 published by the Australian Museum, Sydney communicating knowledge derived from our collections ISSN 0067-1975 (print), 2201-4349 (online) A New Genus and Two New Species of Caprellidae (Crustacea: Amphipoda) from Mesophotic and Deep-sea Waters of Australia José M. Guerra-García1 and Shane T. Ahyong2 1 Laboratorio de Biología Marina, Departamento de Zoología, Facultad de Biología, Universidad de Sevilla, Avda Reina Mercedes 6, 41012, Seville, Spain 2 Australian Museum Research Institute, Australian Museum, 1 William Street, Sydney NSW 2010, Australia, and 2 School of Biological, Earth & Environmental Sciences, University of New South Wales, Kensington NSW 2052, Australia Abstract. Caprellids from mesophotic and deep-sea waters from Australia have been scarcely studied. A new genus Pseudoliropus gen. nov., and two new species Pseudoliropus keablei and Pseudoprotella australiensis sp. nov. are described based on material collected from 56 to 1125 m deep during surveys on board the vessels RV Sprightly (1973), FRV Kapala (1977–1986) and RV Southern Surveyor (2005) along the coast of the Northern Territory, Queensland, New South Wales, Victoria and Tasmania. Pseudoliropus is superficially very close toLiropus but can be readily distinguished by the absence of a mandibular molar (present in Liropus) and 2-articulate mandibular palp (3-articulate in Liropus). Pseudoprotella australiensis can be differentiated from all the remaining species ofPseudoprotella mainly on the basis of the unique body ornamentation (acute projection on the head, pereonites with abundant tiny tubercles scattered over the surface, and rows of lateral tubercles on the proximal end of pereonites 2–4). Further collections in deep ecosystems are mandatory to properly understand global amphipod diversity in Australian waters. Introduction corresponds to the maximum depth at which there is sunlight penetration to support photosynthesis and, hence, the growth The least known ocean regions occur below depths accessible of zooxanthellate coral reefs (Hinderstein et al., 2010). Some to SCUBA diving and include mesophotic ecosystems and coral biologists divide the mesophotic into upper and lower the deep sea (Woodall et al., 2018). portions, with a faunal transition of species around 60 m The past several decades have seen interest in character- (see Baldwin et al., 2018 and references therein). Unlike izing the biodiversity and ecology of mesophotic ecosystems, isolated lower mesophotic reefs (60–150 m), which contain and in particular, mesophotic coral ecosystems (MCEs) (Bell many endemic species, upper mesophotic reefs (30–60 et al., 2018). These are communities of corals, sponges, m) are inhabited by numerous shallow reef organisms algae, associated invertebrates and fishes that occur in threatened by local and global stressors, which find refugia the transition zone between well-lit surface waters and in MCEs (Weinstein et al., 2014). The increasing availability dark deeper waters, usually from 30–40 to 150 m deep of remotely operated vehicles (ROV) and autonomous (Abesamis et al., 2018). The lower limit of the mesophotic underwater vehicles (AUV) (e.g., Englebert et al., 2017; Keywords: mesophotic; deep-sea; Amphipoda; Caprellidae; new taxa; Australia Zoobank registration: urn:lsid:zoobank.org:pub:D7F01FA2-5EBE-4C9C-B2E1-761AEC982532 Corresponding author: José M. Guerra-García [email protected] Received: 7 April 2020 Accepted: 22 May 2020 Published: 24 June 2020 (in print and online simultaneously) Publisher: The Australian Museum, Sydney, Australia (a statutory authority of, and principally funded by, the NSW State Government) Citation: Guerra-García, José M., and Shane T. Ahyong. 2020. A new genus and two new species of Caprellidae (Crustacea: Amphipoda) from mesophotic and deep-sea waters of Australia. Records of the Australian Museum 72(2): 45–62. https://doi.org/10.3853/j.2201-4349.72.2020.1764 Copyright: © 2020 Guerra-García, Ahyong. This is an open access article licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are credited. 46 Records of the Australian Museum (2020) Vol. 72 Figure 1. Localities at which the new genus and the new species were found. Turner et al., 2018), together with new diving technologies 360 million km2, equivalent to about 50% of the surface of that combine Tri-Mix Diving and Rebreathers (e.g., Guerra- the Earth with an average depth of 3,800 m and a maximum García et al., 2015) are contributing to a better knowledge of depth of 10,924 m in the Mariana Trench (Ramirez-Llodra these ecosystems complementing the traditional use of grabs et al., 2011). Nevertheless, as with mesophotic ecosystems, or trawls. Despite this, however, there are still some highly most deep-sea habitats still remain unexplored. For example, diverse geographic areas where mesophotic ecosystems have deep-sea surveys that include amphipods usually reveal that yet to be explored and characterized (Bell et al., 2018) and most of the caprellids collected are new to science (see e.g., taxonomical and ecological studies are still lacking in the Laubitz, 1972; Laubitz & Mills, 1972; Guerra-García, 2003, equatorial Indo-West Pacific region where the most species- 2004; Takeuchi et al., 2016; Zettler et al., 2018). rich coral reefs in the world are highly threatened by human In Australian waters, there is an increasing interest in activities and climate change (see Abesamis et al., 2018 and characterizing mesophotic communities (see e.g., Turner et references therein). Further, most published studies focus al., 2018. in Ningaloo Marine Park, Western Australia) and on sessile flora and fauna, but the small epibiont, vagile the fauna of deep-sea ecosystems (e.g., Horowitz et al., 2018; organisms are often overlooked. Indeed, sporadic sampling Tanner et al., 2018; Williams et al., 2018; MacIntosh et al., in mesophotic ecosystems often reveal the presence of novel 2018; Farrelly & Ahyong, 2019). However, most studies are genera and species of associated macrofauna, such as small mainly focused on larger and most conspicuous organisms and peracarids (e.g., Petrescu et al., 2012; Senna et al., 2014). there is a lack of knowledge dealing with the taxonomy of small The deep sea is considered to start at about 200 meters epibiont organisms (e.g., Lowry & Stoddart, 2010). The present depth, at the shelf break, where a clear change of fauna study deals with the description of new amphipod taxa found from shallow to deep water is observed (Thistle, 2003). The during sampling surveys focused on mesophotic ecosystems waters deeper than 200 m form the largest environment on and deep sea of Australia (Fig. 1). A new genus and two new Earth with a volume of 1368 x106 km3 covering an area of species of Caprellidae are fully described and illustrated. Guerra-García & Ahyong: New mesophotic and deep-sea caprellids 47 Material and methods 133°29'40"E, 136 m depth, RV Southern Surveyor, “Southern Surveyor Arafura Sea Cruise May 2005”, Smith-McIntyre Caprellids were collected by RV Sprightly in 1973, FRV Grab, calcareous muddy gravel with mostly shell fragments Kapala in 1977–1986 and RV Southern Surveyor in May coral, fixed in 5% formalin, preserved 80% ethanol, coll. 2005 (see Wilson, 2005, for details). Specimens of the G.D.F. Wilson, 21 May 2005. Paratypes (collected together new species were dissected in 80% ethanol and slides were with holotype): AM P.101357, paratype “a”, mature female made using Aquatex® mounting medium (Merck Millipore (vial + 1 slide) (mouthparts dissected, used for description, Ltd). Figure plates were made following Takeuchi (2015) figured); AM P.101358, 2 premature females (not dissected). and Guerra-García et al. (2020). Firstly, original sketches of lateral view, antennae, gnathopods, pereopods and Etymology. This species is dedicated to our friend and mouthparts were drawn using a Leica compound microscope colleague Dr Stephen Keable. JMGG is very grateful to him equipped with a camera lucida. Figures were inked using for his continuous support, help and friendship during visits Rotring pens based on the reduced copies of the original to the Australian Museum. sketches organized in plates. Finally, with Photoshop 6, Diagnosis. Eyes present, although with few ommatidia. drawings were improved, cleaned and final plates arranged. Body of male covered by abundant tiny dorsal tubercles Body length was measured from the anterior end of the from pereonite 2–5 and basis of gnathopod 2; pereonite head to the posterior end of pereonite 7. The symbols used 2 with small acute anterolateral projections; pereonites 3 in the present work are: A1, 2 = Antenna 1, 2; UL = Upper and 4 with small, serrate, anterolateral projections. Body lip; LL = Lower lip; LMd = Left mandible; RMd = Right of female smooth. Maxilliped palp article 3 without distal mandible; Mx 1, 2 = Maxilla 1, 2; Mxp = Maxilliped; Gn 1, 2 projection. Mandibular molar absent; palp with 2 apical = Gnathopod 1, 2; P5–7 = Pereopod 5–7; Ab = Abdomen. In setae. Gnathopod 2 basis shorter than pereonite 2. Pereopods the descriptions, the term “spine” is used for stout, inflexible 3 and 4 1-articulate. Pereopod 5 3-articulate. Abdomen articulated structures, “seta” for slender, flexible articulated without appendages. structures and “setule” for very short setae. Systematic classification was based on Lowry & Myers (2013, 2017). Description. Holotype male AM P.79076 (3.3 mm) Specimens of the new genus and species are deposited in Lateral view (Fig. 2). Body dorsally covered by tiny dorsal the Australian Museum (AM). tubercles on pereonites 2–5 and basis of gnathopod 2. Eyes with few ommatidia. Pereonite 1 fused with head, suture present. Small, acute anterolateral projections on pereonite Taxonomic account 2 and small serrate anterolateral projections on pereonites 3–4. Pereonite 5 longest.