Pseudoliropus keablei, Guerra-García & Ahyong, 2020

Guerra-García, José M. & Ahyong, Shane T., 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), pp. 45-62 : 47-52

publication ID	https://doi.org/ 10.3853/j.2201-4349.72.2020.1764
publication LSID	lsid:zoobank.org:pub:5DF8D669-A569-457E-83BF-CD326224647E
DOI	https://doi.org/10.5281/zenodo.4654264
persistent identifier	https://treatment.plazi.org/id/3B4FFD1E-DB4D-FF9F-571A-8FE873D3E2E6
treatment provided by	Felipe
scientific name	Pseudoliropus keablei
status	sp. nov.

Treatment

Pseudoliropus keablei sp. nov.

http://zoobank.org/NomenclaturalActs/ B6A4E2C2-C597-413E-A0B6-19DF72908CB6

Figs 2–5 View Figure 2 View Figure 3 View Figure 4 View Figure 5

Holotype: AM P.79076, mature male (vial + 3 slides) (mouthparts dissected, used for description, figured), Arafura Sea , Area C South, Northern TerritorY, Australia, 9°10'32"S 133°29'40"E, 136 m depth, RV Southern Surveyor, “Southern SurveYor Arafura Sea Cruise MaY 2005 ”, Smith-McIntYre Grab, calcareous muddY gravel with mostlY shell fragments coral, fixed in 5% formalin, preserved 80% ethanol, coll. G.D.F. Wilson, 21 MaY 2005 GoogleMaps . Paratypes (collected together with holotYpe) GoogleMaps : AM P.101357, paratype “a”, mature female (vial + 1 slide) (mouthparts dissected, used for description, figured) ; AM P.101358, 2 premature females (not dissected).

Etymology. This species is dedicated to our friend and colleague Dr Stephen Keable. JMGG is verY grateful to him for his continuous support, help and friendship during visits to the Australian Museum.

Diagnosis. EYes present, although with few ommatidia. BodY of male covered bY abundant tinY dorsal tubercles from pereonite 2–5 and basis of gnathopod 2; pereonite 2 with small acute anterolateral projections; pereonites 3 and 4 with small, serrate, anterolateral projections. BodY of female smooth. Maxilliped palp article 3 without distal projection. Mandibular molar absent; palp with 2 apical setae. Gnathopod 2 basis shorter than pereonite 2. Pereopods 3 and 4 1-articulate. Pereopod 5 3-articulate. Abdomen without appendages.

Description. Holotype male AM P.79076 (3.3 mm)

Lateral view ( Fig. 2 View Figure 2 ). BodY dorsallY covered bY tinY dorsal 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 2 and small serrate anterolateral projections on pereonites 3–4. Pereonite 5 longest. Pereonite 7 shortest.

Gills ( Fig. 2 View Figure 2 ). Present at middle of pereonites 3–4, small, oval, length about 1.5 × width.

Mouthparts ( Fig. 3 View Figure 3 ). (Maxilliped and mandibles figured and described from holotYpe male; maxilla 1 and 2, upper and lower lips figured and described from paratYpe “a” female). Mouthparts remarkablY small (ca. 0.05 mm; 0.015 × bodY length). Mandibular molar absent; palp 2-articulate, distal article the longest, with 2 apical setae; left mandible with incisor and lacinia mobilis 5-dentate, accessorY blades not clearlY distinguished; incisor of right mandible 5-dentate, lacinia mobilis blade-like, followed bY 2 more blades; no trace of molar flake. Upper lip without setae. Lower lip without setae, inner lobes apparentlY fused. Maxilla 1 outer lobe with 5 spines; palp 2-articulate, distal article with 3 apical spines and medial seta. Maxilla 2 inner and outer lobe of similar size, small, each with 3 distal setae. Maxilliped inner plate small, length about 1/4 outer plate length, with 2 apical setae; outer plate elongate, with 4 or 5 setae; palp 4-articulate, article 2 with distal seta, article 3 with 2 apical setae, article 4 with few setulae.

Antennae ( Figs 2 View Figure 2 , 4 View Figure 4 ). Antenna 1 ca. 1/5 bodY length; flagellum 4-articulate. Antenna 2 about 1/2 length of antenna 1; proximal peduncular article with acute gland cone distallY; swimming setae absent; flagellum 2-articulate.

Gnathopods ( Figs 2 View Figure 2 , 4 View Figure 4 ). Gnathopod 1 basis as long as ischium, merus and carpus combined; occlusal margin of propodus smooth, with row of fine setulae; 2 proximal grasping spines, dactYlus bifid distallY and with row of setulae. Gnathopod 2 inserted on anterior half of pereonite 2; coxa with distal projection (see detail in Fig. 2 View Figure 2 ); basis about 2/3 length of pereonite 2, with tinY tubercles similar to those on pereonites; ischium rectangular; basis and ischium with distal projection laterallY; merus rounded; carpus short, triangular; propodus palm with proximal projection with large grasping spine, serrated area, medial projection, and 2 more projections distallY ( Fig. 4 View Figure 4 ); dactYlus smooth and elongate, with verY fine setulae onlY.

Pereopods ( Figs 2 View Figure 2 , 5 View Figure 5 ). Pereopods 3 and 4 tinY (ca. 0.01 mm, 0.003 × bodY length), 1-articulate, with distal seta. Pereopod 5 3-articulate, inserted at middle of pereonite 5, proximal and medial article with seta, distal article with 5 lateral setae and distal seta. Pereopods 6 and 7 6-articulate, with plumose setae; propodus of pereopod 6 proximal projection with proximal grasping spine; proximal projection of propodus of pereopod 7 larger, with grasping spine and plumose setae; dactYlus curved.

Penes ( Fig. 5 View Figure 5 ) large, situated laterallY, distinctive, elongate, length ca. 3× width.

Abdomen ( Fig. 5 View Figure 5 ) lacking appendages; pair of lobes with 2 setae, and single dorsal lobe.

Paratype female “a” AM P. 101357 (3.1 mm) ( Figs 2–5 View Figure 2 View Figure 3 View Figure 4 View Figure 5 ). Similar to male except as follows: bodY smooth, lacking tinY tubercles or anterolateral projections; pereonites 3 and 4 with oostegites; antenna 1 flagellum 3-articulate; gnathopod 2 basis without tinY tubercles, basis and ischium lacking distal projection, palm of propodus with proximal projection provided with grasping spine and margin serrated ventrallY, medial projection absent. Abdomen lacking setae .

Remarks. The genus Liropus was established bY MaYer (1890) and currentlY includes 14 species ( Guerra-GarcÍa et al., 2018). A morphological comparison among species of Liropus species is provided bY Guerra-GarcÍa & HendrYcks (2013), Mauro & Serejo (2015) and Sánchez-MoYano et al. (2015), and an illustrated keY to the species was given bY Guerra-GarcÍa & HendrYcks (2013). The new genus Pseudoliropus is superficiallY verY close to most species of Liropus , sharing short antennae, pereonite 5 elongate in males, and reduced pereopods 3–5. The two genera differ primarilY in the mouthparts: (i) mandibular molar is present in Liropus but absent in Pseudoliropus ; and (ii) the mandibular palp is 3-articulate in Liropus but 2-articulate in Pseudoliropus .

The specimens of Pseudoliropus keablei gen. nov, sp. nov. were collected from the Arafura Sea. The Arafura Sea is a continental shelf basin between northern Australia and Indonesian land masses, overlYing part of the Sahul Shelf that straddles the Indian Ocean-Australian continental plates ( Wilson, 2005). Area C South, the zone from which the specimens were collected, is on the southern flank of Pillar Bank, with depths ranging from 136– 182 m. The shallower stations were higher on the bank and consisted of coarser sediments with several grab and rock dredge samples that collected oYster shells, coral and brYozoan fragments. The deeper sites consisted of soft bioturbated sediments with few epifauna ( Wilson, 2005). The water temperatures were 14–16°C in the deeper regions of Area C (depth 230 m). Although these temperatures are not tYpical deep-sea temperatures (tYpicallY below 8°C), some deep-water faunal elements, such as stalked crinoids, hexactinellid sponges and deep-water pedunculate barnacles were observed (see Wilson, 2005 for details).