Orthoprotella pearce, 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 : 445-447

Orthoprotella pearce n.sp.

Figs 47–51

Type material. HOLOTYPE 3, AM P61740, Pidgin Point, Lizard Island , Queensland, on hydroid Halopteris buskii , 5–10 m, QLD 1580, J.M. Guerra-García & S.J. Keable, 18 Oct 2001 . PARATYPES: 1♀, AM P61741, type locality; 533 , 2♀♀, 4 juveniles, AM P61742, type locality ; 2♀♀, 1 juvenile, AM P61743, Coconut Beach, Lizard Island , Queensland, on hydroid Macrorhynchia philippina , 4 m, QLD 1474, J.M. Guerra-García & S.J. Keable, 8 Oct 2001 .

Etymology. This species is dedicated to Marianne and Lance Pearce, the accommodation and maintenance officers of Lizard Island Research Station, for help, encouragement and hospitality during the field study at Lizard Island; used as a noun in apposition.

Diagnosis. A pair of anterolateral projections on pereonites 2–4 in males and 2–3 in females. Distal article of the mandibular palp with a setal formula 1-x-1, being x=7. Distal projection of the third article of maxilliped palp absent. Pereopods 3 and 4 uniarticulate.A pair of 2-articulate abdominal appendages in males.

Description

Holotype male. Body length. 5.6 mm. Lateral view ( Figs 47A). Body smooth except for three pairs of lateral acute projections on pereonites 2–4. Pereonites 3 and 4 subequal in length; pereonite 7 the shortest. Gills ( Fig. 47A). Present on pereonites 3–4, elongate, length almost 3 times width. Mouthparts. Upper lip ( Fig. 48B) symmetrically bilobed, not setose apically. Mandibles ( Fig. 49A,B) with 3-articulate palp; distal article of palp with nine setae following the formula 1-x-1, being x=7; second article of the palp with three setae on the right mandible ( Fig. 49A) and two setae on the left mandible ( Fig. 49B); mandibular molar present, bordered by robust teeth; left mandible with incisor 5- toothed, lacinia mobilis 5-toothed followed by three plumose setae; incisor of right mandible 5-toothed, lacinia mobilis serrate, followed by two plumose setae; molar flake present on right mandible with short setulae distally. Lower lip ( Fig. 48C) with inner lobes clearly smaller than outer lobes, well demarcated; inner and outer lobes smooth. Maxilla 1 ( Fig. 48D) outer lobe with seven robust setae, serrate laterally; distal article of palp with four apical robust setae and a row of four setae medially. Maxilla 2 ( Fig. 48E) inner lobe with six setae distally; outer, about 1.3 times as long as inner lobe, with six apical setae. Maxilliped ( Fig. 48A) inner plate rectangular with one nodular robust and short setae and three simple setae; outer plate large, about 3 times as long as inner plate, with one acute seta apically and six setae laterally; margin distally crenulated; palp fourarticulate, setose, dactylus with rows of setulae. Antennae. Antenna 1 ( Fig. 50A) about 2 ⁄ 3 body length; distal article of the peduncle short, about 1 ⁄ 3 length of preceding article; flagellum 1 3-articulate. Antenna 2 ( Fig. 50B) about half width of antenna 1; swimming setae absent; proximal article of the peduncle with a distal projection; flagellum 2- articulate. Gnathopods. Gnathopod 1 ( Fig. 50C) basis as long as ischium, merus and carpus combined; merus and carpus setose; propodus setose, length about 1.5 times width, palm with a row of minute setulae proximally, one pair of grasping spines, followed by a row of five smaller grasping spines and four setae; dactylus with a dorsal setae proximally and two lateral setae on the distal end, which is divided. Gnathopod 2 ( Fig. 50D) inserted on the anterior part of pereonite 2 ( Fig. 47A); basis about 3 ⁄ 4 as long as pereonite 2, with acute distal projection; ischium rectangular with a small rounded projection; merus rounded; carpus triangular; propodus about 1.2 times as long as basis, with acute distal projection dorsally, palm provided with one grasping spine proximally, followed by several setae and U-notch; dactylus elongate and curved, smooth. Pereopods. Pereopods 3 and 4 reduced ( Fig. 51A,B) about 1 ⁄ 3 as long as gills, onearticulate, provided with five setae. Pereopods 5–7 ( Fig. 51C–E) six articulate, palm of the propodus with a pair of grasping spines. Penes. ( Fig. 51F) Small, rounded, as long as wide. Abdomen. ( Fig. 51F) With a pair of appendages and single dorsal lobe; appendages 2-articulate, positioned on setose peduncles (which are projections of the body); proximal article elongate, with small distal setulae; distal article about 1 ⁄ 5 as long as proximal article, with two apical setae; dorsal lobe with two plumose setae.

Paratype female. Body length 5.4 mm. Lateral projections on pereonite 4 lacking ( Fig. 47B). Oostegites on pereonite 3 setose, on pereonite 4 not setose ( Fig. 47B). Gnathopod 2 similar to male ( Fig. 50E). Abdomen ( Fig. 51G) without appendages.

(A) right mandible; (B) left mandible mandible. Scale: 0.1 mm.

Remarks. The new species of Orthoprotella is close to O. mayeri and they can be distinguished only with observation of the lateral view and careful examination of the mouthparts. Orthoprotella mayeri presents the pereopods 3 and 4 as 2-articulate, although the distal article is tiny and difficult to detect, whilst in O. pearce these pereopods are uni-articulate. In connection with the mouthparts, the distal article of the mandibular palp in O. mayeri presents a setal formula 1-x-y-1 being x>20 and y=2-4, while the formula in O. pearce is 1-x-1 with x=7; furthermore, the distal projection of the third article of the maxilliped palp, present in O. mayeri , is absent in O. pearce .

Distribution. Presently known only from Lizard Island, Queensland.

gnathopod 2; (E) paratype female (AM P61741) gnathopod 2 .

Scales: A,B,D,E: 0.5 mm; C: 0.2 mm.