Ischyrocerini, Kroyer, 1838

Conlan, Kathleen E., 2021, New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini, Zootaxa 4921 (1), pp. 1-72 : 61-62

publication ID

https://doi.org/ 10.11646/zootaxa.4921.1.1

publication LSID

lsid:zoobank.org:pub:2A77E821-52F4-450C-8964-7928D36C0906

DOI

https://doi.org/10.5281/zenodo.4534341

persistent identifier

https://treatment.plazi.org/id/03DFE565-EA40-D454-FF13-3270D0F8FF10

treatment provided by

Plazi

scientific name

Ischyrocerini
status

 

Key to genera of the Ischyrocerini View in CoL

1 Urosome 1 bearing 3 dorsal teeth or cusps ( Fig. 35a View FIGURE 35 ).................................. Bathyphotis Stephensen, 1944

– Urosome 1 without dorsal teeth although there may be a pair of short setae ( Fig. 35b View FIGURE 35 )............................... 2

2 Pereopods 5–7, ischium posteriorly winged ( Fig. 35c View FIGURE 35 ). Uropod 3 uniramous, ramus ending in a cluster of spines ( Fig. 35e View FIGURE 35 ).................................................................................. Alatajassa Conlan, 2007 View in CoL

– Pereopods 5–7, ischium not posteriorly winged ( Fig. 35d View FIGURE 35 ). Uropod 3 biramous ( Fig. 35f View FIGURE 35 )...............................3

3 Pereopods 3–4, propodus prehensile ( Fig. 35g View FIGURE 35 )......................................... Isaeopsis K.H. Barnard, 1916 View in CoL

– Pereopods 3–4, propodus rectangular or oval and not expanded distally ( Fig. 35h View FIGURE 35 ).....................................4

4 Coxa 4 posteriorly excavate ( Fig. 35i View FIGURE 35 )........................................................................5

– Coxa 4 not posteriorly excavate (though it may be shallowly concave) ( Fig. 35j View FIGURE 35 )......................................7

5 Gnathopod 1, carpus longer than the propodus (carpus:propodus length ~125%). Gnathopod 2, female, propodus massive, length ~175% the length of the propodus of gnathopod 1, palm toothed ( Fig. 35k View FIGURE 35 )............. Veronajassa Vader and Myers, 1996 View in CoL

– Gnathopod 1, carpus subequal to or shorter than the propodus (carpus: propodus length ~45–95%). Gnathopod 2, female, propodus not massive, length ~125% the length of the propodus of gnathopod 1, palm not toothed ( Fig. 35l View FIGURE 35 )....................6

6 Eyes absent. Maxilla 1, inner plate with a long apical seta ( Fig. 36a View FIGURE 36 ). Coxa 1 more than half the depth of coxae 2–4. Gnathopod 1, carpus length ~95% the length of the propodus; propodus, palm shallowly excavate ( Figs 36c, d View FIGURE 36 )................................................................................................. Myersius Souza-Filho & Serejo, 2014 View in CoL

– Eyes present. Maxilla 1, inner plate without a long apical seta ( Fig. 36b View FIGURE 36 ). Coxa 1 ± half the depth of coxae 2–4. Gnathopod 1, carpus length ~45–50% the length of the propodus; propodus, palm convex ( Figs 36e, f View FIGURE 36 )........... Microjassa Stebbing, 1899 View in CoL

7 Gnathopod 1, carpus ~100% the length of the propodus. Pereopods 3 and 4, dactyl ~175% the length of the propodus ( Fig. 36g View FIGURE 36 )................................................................................ Scutischyrocerus Myers, 1995 View in CoL

– Gnathopod 1, carpus shorter than the propodus. Pereopods 3 and 4, dactyl ±90% the length of the propodus ( Fig. 36h View FIGURE 36 )........8

8 Uropod 3 with a cluster of distolateral setae beside the outer ramus ( Fig. 36i View FIGURE 36 ). Jassa View in CoL group..............................9

– Uropod 3 without a cluster of distolateral setae beside the outer ramus Fig. 36j View FIGURE 36 )......................................13

9 Antenna 1, accessory flagellum absent or scale-like ( Fig. 37a View FIGURE 37 )................................ Parajassa Stebbing, 1899 View in CoL

– Antenna 1, accessory flagellum 2 articles, the second minute ( Fig. 37b View FIGURE 37 )............................................10

10 Gnathopods and pereopods 3–4 clothed in abundant, long plumose setae ( Fig. 3 View FIGURE 3 ). Gnathopod 2, either sex, propodus, palm bearing a central tooth and a second tooth at the palmar angle, with or without a single large spine at the palmar angle ( Fig. 37c View FIGURE 37 )............................................................................................. Plumulojassa View in CoL n. gen.

– Gnathopods and pereopods 3–4, setae simple or finely pectinate except in the palm of the male gnathopod 2 where the setae may be plumose ( Figs 17 View FIGURE 17 , 22 View FIGURE 22 , 25 View FIGURE 25 and 27– 29 View FIGURE 27 View FIGURE 28 View FIGURE 29 ). Gnathopod 2, either sex, propodus, palm sinuous, concave or with a pronounced thumb defining the palm proximally, spines if present grouped in triplicate or if single, very small ( Figs 37 View FIGURE 37 d–f)..................11

11 Gnathopods 1 and 2, propodus, palm defined by 1 spine. Gnathopod 2 without a gill. Pereopod 5, carpus with a cluster of spines posterodistally. Pleopods, rami very short, length ± depth of the pleon ( Figs 22–28 View FIGURE 22 View FIGURE 23 View FIGURE 24 View FIGURE 25 View FIGURE 26 View FIGURE 27 View FIGURE 28 )....................... Pleojassa View in CoL n. gen.

– Gnathopods 1 and 2, propodus, palm defined by multiple spines (usually 3–4). Gnathopod 2 with a gill. Pereopod 5, carpus not spinose posterodistally. Pleopods, rami long, length> depth of the pleon ( Fig. 17 View FIGURE 17 )....................................12

12 Gnathopod 2, propodus, both sexes producing a thumb at adulthood, palmar defining spines, if present, at the thumb tip ( Fig. 37e View FIGURE 37 ), juvenile palm sinuous, without a thumb; pereopods 3 and 4, carpus <25% overlapped by the merus; uropod 3, outer ramus with many minute cusps proximal of the dorsally recurved terminal spine but without additional larger cusps ( Figs 17–21 View FIGURE 17 View FIGURE 18 View FIGURE 19 View FIGURE 20 View FIGURE 21 )............................................................................................. Hemijassa Walker, 1907 View in CoL

– Gnathopod 2, propodus, only the male producing a thumb at adulthood, palmar defining spines, if present, proximal of the thumb tip ( Fig. 37f View FIGURE 37 ), juvenile palm concave or sinuous, without a thumb; pereopods 3 and 4, carpus 80–100% overlapped by the merus; uropod 3, outer ramus with 2 (usually) larger cusps in addition to minute cusps proximal of the dorsally recurved terminal spine ( Figs 35b,d,f,h View FIGURE 35 , 36 h,i View FIGURE 36 and 37f View FIGURE 37 )................................................................ Jassa Leach, 1814 View in CoL

13 Uropods 1, 2 and/or 3, peduncle with lateral row of setae ( Fig. 37g View FIGURE 37 )..................... Ruffojassa Vader and Myers View in CoL , 19961

– Uropods 1, 2 and/or 3, peduncle without a lateral row of setae...................................................14

14 Antenna 1, accessory flagellum 3–4 articles, the last minute. Uropod 3, outer ramus with one to several medial setae projecting dorsally ( Fig. 37h View FIGURE 37 )................................................................ Ventojassa J. L. Barnard, 1970 View in CoL

– Antenna 1, accessory flagellum 1–2 articles, the last minute. Uropod 3, outer ramus without medial setae projecting dorsally.........................................................................................................15

15 Gnathopod 1, carpus longer than the propodus (carpus ~120% of the propodus length). Known only from subantarctic islands and Brazil, 44–1058 m ......................................................... Pseudischyrocerus Schellenberg, 1931 View in CoL

– Gnathopod 1, carpus shorter than the propodus (carpus ~50–95% of the propodus length). Various locations and depths......16

16 Mandibular palp, article 3 slender, ventrally convex and broadest centrally, tip acute ( Fig. 37i View FIGURE 37 ). Antennae 1 and 2, length Ξ85% of the body length (headlobe to end of uropods), antenna 2 not stouter than antenna 1. Pereopods 3 and 4, merus not overlapping the carpus anteriorly. Uropod 2, outer ramus, length 65% of the inner ramus....................... Paradryope Stebbing , 18882

– Mandibular palp, article 3 broad distally, end rounded ( Fig. 37j View FIGURE 37 ). Antennae 1 and 2, length ±65% of the body length (headlobe to end of uropods), antenna 2 stouter than or similar to antenna 1. Pereopods 3 and 4, merus overlapping 10–100% of the carpus. Uropod 2, outer ramus, length 75–80% of the inner ramus.......................................................17

17 Adult male gnathopod 2 grossly lengthened and pendulate, length 190–350% of the length of gnathopod 1, propodus slender, length 180–400% of its width at the centre, dactyl 50–100% of the length of the propodus ( Figs 38 View FIGURE 38 a-c). Uropod 3 with 1–2 rows of mid-dorsal spines but without a corona of multiple spines on the distal margin ( Fig. 38d View FIGURE 38 ). Warm temperate and tropical, Northern and Southern Hemisphere, known from 9– 40°N and 5– 34°S, 0–16 m depth ................... Neoischyrocerus Conlan, 1995 View in CoL

– Adult male gnathopod 2 variable in length but not pendulate, length 100–220% of the length of gnathopod 1, propodus variably slender or stout, length 120–290% of its width at the centre, dactyl 33–75% of the length of the propodus ( Figs 38 View FIGURE 38 e-g). Uropod 3 with 1–2 rows of mid-dorsal spines and a corona of numerous spines on the distal margin 3 ( Fig. 38h View FIGURE 38 ). Cold temperate and polar, primarily Northern Hemisphere, known from 36– 81°N and 42°S, 1–2000 m depth............... Ischyrocerus Krøyer, 1838

Kingdom

Animalia

Phylum

Arthropoda

Class

Malacostraca

Order

Amphipoda

Family

Ischyroceridae

Tribe

Ischyrocerini

Genus

Ischyrocerus

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