Perotripus keablei, Guerra-García, 2006

Guerra-García, J. M., 2006, Caprellidae (Crustacea: Amphipoda) from the Great Barrier Reef and Adjacent Localities, Records of the Australian Museum 58, pp. 417-458 : 431-433

Perotripus keablei n.sp.

Figs 24–27

Type material. HOLOTYPE 3, AM P61747, off Mangrove Beach, Lizard Island , Queensland, 14°40'S 145°28'E, sand, 1.5 m, GBR 6, C. Short & A.R. Jones, 30 Sep 1978 . PARATYPES (all Lizard Island, Queensland): 1♀, AM P61748, between Bird Islet & Trawler Beach, 14°40'S 145°28'E, sand, 15 m, GBR 14, J.K. Lowry & P.C. Terrill, 5 Oct 1978 ; 1♀, AM P32295, Lagoon , 14°41'S 145°28'E, 1.5 m, GBR 5, C. Short & P.C. Terrill, 30 Sep 1978 ; 333, 4♀♀, AM P32304, type locality ; 1♀, AM P32293, between Mangrove Beach & South Island , 14°40'S 145°28'E, sand, 9 m, GBR 7, J.K. Lowry & P.C. Terrill, 30 Sep 1978 ; 1♀, AM P32297, off S end Casuarina Beach , 14°40'S 145°28'E, beach sand, low water mark, GBR 10, J.K. Lowry, 4 Oct 1978 ; 533, 6♀♀, AM P61749, type locality; 1 premature ♀, AM P32298, between Bird Islet & South Island , 14°40'S 145°28'E, coral rubble, 21 m, GBR 15, A.R. Jones, 7 Oct 1978 ; 1♀, AM P32294, Mermaid Cove , 14°41'S 145°28'E, sand between corals, 6 m, GBR 26, C. Short & P.C. Terrill, 8 Oct 1978 ; 1♀, AM P32296, Between Bird Islet & South Island , 14°41'S 145°28'E, sediment at reef base with mixed algae, 25 m, GBR 29, J.K. Lowry, 9 Oct 1978 ; 13, AM P61750, Blue Lagoon , between Bird Islet and South Island, sediment (medium grained sand), 6 m, QLD 1538, J.M. Guerra- García & S.J. Keable, 13 Oct 2001 .

Etymology. Named after Stephen Keable, Australian Museum, for his assistance during the sampling at Lizard Island and for his encouragement, advice, help and friendship during my stay at the Australian Museum.

Diagnosis. Body dorsally smooth. Gills on pereonites 2–4. Flagellum of antenna 1 2-articulate. Pereopods 3 and 4 uniarticulate. Pereopod 5 with 3 articles.Abdomen without appendages.

Description

Holotype male. Body length. 5.2 mm. Lateral view ( Fig. 24A). Body dorsally smooth. Head rounded. Pereonite 1 fused with head, suture almost absent; pereonites 2 and 3 rounded; pereonites 4–6 elongate; pereonites 5 and 6 subequal in length; pereonite 7 the shortest. Gills ( Fig. 24A). Present on pereonites 2–4, oval, length about two times width. Mouthparts. Upper lip ( Fig. 25C) symmetrically bilobed, smooth apically. Mandibles ( Fig. 25A,B) with 3-articulate palp; distal article of palp with one simple apical seta and minute setulae distally; second article with a simple setae; mandibular molar absent; left mandible ( Fig. 25A) with 6-toothed incisor, lacinia mobilis 6-toothed followed by three plates decreasing in size respectively; incisor of right mandible ( Fig. 25B) 6-toothed, lacinia mobilis transformed into a plate, followed by four more plates decreasing in size respectively. Lower lip ( Fig. 25D) with inner lobes fused, forming a semicircular plate; outer lobes with some setulae distally. Maxilla 1 ( Fig. 25F) outer lobe with five robust setae, serrate laterally; distal article of the palp with two apical setae and row of three setae medially. Maxilla 2 ( Fig. 25G) inner lobe with 3 distal setae; outer lobe about 1.3 times as long as inner lobe, with 3 setae. Maxilliped ( Fig. 25E) inner plate rectangular, with three setae distally; outer plate triangular, as long as inner plate; palp four-articulate, dactylus with a row of setulae. Antennae. Antenna 1 ( Fig. 26A) about 1/12 body length; flagellum 2-articulate. Antenna 2 ( Fig. 26B) about 2 ⁄ 3 length of antenna 1; swimming setae absent; flagellum 2-articulate. Gnathopods. Gnathopod 1 ( Fig. 26C) basis as long as the ischium, merus and carpus combined; propodus oval, length about 1.2 times width, palm serrate proximally with a grasping spines and two rows of smaller spines along the palm; dactylus elongate and slightly curved, smooth. Gnathopod 2 ( Fig. 26D) inserted on anterior half of pereonite 2 ( Fig. 24A); basis length one-half of pereonite 2; ischium rectangular; merus rounded; carpus short and triangular; propodus oval, about 1.3 times as long as basis; palm with three grasping spines proximally and two rows of smaller spines along palm; dactylus short and slightly curved, with dorsal seta proximally. Pereopods. Pereopods 3 and 4 ( Fig. 27A,B) subequal, small and one-articulate, with two setae distally. Pereopod 5 ( Fig. 27C) 3-articulate and sparsely setose. Pereopods 6 and 7 six-articulate ( Fig. 27D,E). Propodus of pereopod 6 with large spine followed by three smaller spines, distally robust, propodus of pereopod 7 without spines (missing in holotype, described from a male paratype). Penes ( Fig. 27F) positioned medially, large, length about 2.5 times width. Abdomen ( Fig. 27F) without projections except for two lateral lobes and one dorsal lobe.

Paratype female. Body length 2.7 mm. Pereonites 4–6 ( Fig. 24B) shorter than in male; propodus of gnathopod 2 ( Fig. 26E) twice as long as wide. Oostegites sparsely setose ( Fig. 24B). Palm of pereopod 6 without spines ( Fig. 24B).

Remarks. The only other known species of Perotripus is P. brevis (La Follette, 1915) from the west coast of North

Distribution. Presently known only from Lizard Island, Queensland, Australia.