Prachynella lodo J.L. Barnard, 1964

Lowry, J. K. & Stoddart, H. E., 2012, The Pachynidae fam. nov. (Crustacea: Amphipoda: Lysianassoidea) 3246, Zootaxa 3246 (1), pp. 1-69 : 46-50

Prachynella lodo J.L. Barnard, 1964

( Fig. 34 )

Prachynella lodo J.L. Barnard, 1964: 233 (in part, illustrated specimen = P. oculata sp. nov.). ―J.L. Barnard, 1966a: 70 (possibly in part). ―J.L. Barnard, 1966b: 26 (in part, part = P. oculata sp. nov.). ―J.L. Barnard, 1967: 69 (in part, not figs 29,

30) [see Remarks]. ― Lowry 1984: 72, figs 13–15. ― Austin, 1985: 601. ― Barnard & Karaman, 1991: 520. ―García-

Madrigal, 2007: 108. not Prachynella lado (sic). ― Hirayama, 1985: 182, figs 175–178 (= P. shijiki sp. nov.). not Prachynella lodo . ― Ishimaru, 1994: 59 (= P. shijiki sp. nov.).

Material examined. Holotype, female, 5.8 mm, LACM 57 - 210.1 , south-east of San Mateo Point , southern California, USA, 33°17’35”N 117°31’00”W, 24 m, 20 February 1957, Velero IV station 4868. – 1 female, 7.6 mm, LACM, off Santa Barbara, southern California, station 5261. – about 45 specimens, LACM, southern California, USA, 12– 157 m, 1956–1959, from 40 Velero IV stations (all identified by J.L. Barnard as P. lodo ). –1 ovigerous female, as 1 slide, NMCC 1990-0550 , McCauley Point , Vancouver Island, British Columbia, Canada, eastern North Pacific Ocean, [approx. 48°24'N 123°24'W], 49 m, July 1977, G.W. O'Connell, stn W3-AO.

Description. Head lateral cephalic lobe large, broadly rounded; ventral margin curved. Antenna 1 peduncular article 1 with posterodistal spine; accessory flagellum 2-articulate, article 1 short; flagellum with strong 1-field callynophore in female, strong 2-field in male. Mandible lacinia mobilis a simple robust seta; lamina dentata vestigial; accessory setal row absent; molar absent; palp attached distally; palp article 2 broad, subequal to article 3; article 3 with subparallel margins. Maxilla 1 outer plate with 10 setal-teeth in 7/3 arrangement, most outer row setalteeth with medial cusps; palp vestigial, 1-articulate, apical setae absent. Maxilliped inner plate small; outer plate large; palp 3-articulate (articles 1 and 2 fused). Gnathopod 1 chelate; ischium smaller than propodus, not swollen posteroproximally; carpus extremely compressed; propodus length about 1.9 × breadth, posterior margin well developed, plam with produced corner, pollex length about 1.2 × breadth, corner of palm with complex robust seta; dactylus reaching to corner of palm. Gnathopod 2 palm minute, obtuse. Pereonite 4 without dorsal spines. Pereonite 5 with 1 acute dorsal spine. Pereopod 5 merus with posteroproximal shoulder. Pereopod 6 basis with posteroventral lobe weakly produced; merus longer than broad, with posteroproximal shoulder. Pereopod 7 basis subovate with posterior margin smooth or weakly dentate. Epimeron 3 posterior margin without projections, posteroventral corner broadly rounded. Uropod 3 biramous, inner ramus extending more than halfway along outer ramus but not reaching base of article 2. Telson shorter than broad, weakly emarginate.

Remarks. As pointed out by Lowry (1984: 72), when J.L. Barnard (1964) established the species P. lodo he described and illustrated one specimen but designated another specimen as the holotype. Lowry (1984: figs 13–15) illustrated the holotype of P. lodo and noted some differences between it and the material illustrated by J.L. Barnard. We have examined a large amount of material from southern California identified as P. lodo by J.L. Barnard. This material contains two species: P. lodo and the species actually illustrated by J.L. Barnard (1964, fig. 7 and 1967, fig. 29) which we establish below as P. oculata sp. nov.

Although extremely similar, P. lodo and P. oculata can be distinguished by the shape of the dorsal spine on pereonite 5 (posteriorly acute in P. lodo , rounded in P. oculata ) and by the shape of gnathopod 1 propodus: the pollex (or fixed finger) in P. lodo is considerably stockier than that in P. oculata , the length-to-breadth ratio being about 1.2 in P. lodo and 1.8 in P. oculata .

We have re-examined the holotype of P. lodo and find that the left mandible has a lacinia mobilis and a vestigial ridge possibly representing the accessory robust setae or a lamina dentata. The single specimen from Vancouver Island also has a poorly developed ridge on the left mandible.

J.L. Barnard (1967) recorded one specimen from Cedros Trench station 7234 as an “anoculate form” of P. lodo , and illustrated some parts in fig. 30a–g. The vial now contains only a heavily-dissected carcass and no loose parts. The body is intact but there are no mouthparts, no right-side limbs and no left pereopods below the coxae. There is definitely no dorsal spine on pereonite 4 or 5. We cannot place this specimen, but can say that it is not P. lodo or P. oculata .

Distribution. Eastern Pacific Ocean: Vancouver Island, British Columbia, Canada; southern California, USA; Baja California, Mexico.

Figures

FIGURE 34. Prachynella lodo J.L. Barnard, 1964. Holotype female, 5.8 mm, LACM 57-210.1, Mateo Point, California, USA. Whole animal, female, 7.6 mm, LACM, off Santa Barbara, southern California, USA. Scales for MD, MX1 represent 0.1 mm, remainder represent 0.2 mm.