Ischioscia, VERHOEFF, 1928

Campos-Filho, Ivanklin Soares, López-Orozco, Carlos Mario, Carpio-Díaz, Yesenia M., Águiar, José Otávio & Navas, Gabriel R., 2020, Three new species of Ischioscia Verhoeff, 1928 (Isopoda, Oniscidea, Philosciidae) from Serranía de Perijá, Andean Cordillera, Colombian Caribbean, Zoosystema 42 (8), pp. 115-130 : 127-128

KEY TO THE SPECIES OF ISCHIOSCIA VERHOEFF, 1928

1. Pereonites 1-7 dorsally pigmented in brown colour with typical unpigmented spots at muscle insertions; male pleopod 1 exopod cordiform ....................................................................................................................... 2

— Pereonites 1 and 5 completely pigmented, 2-4 and 7 with well pigmented areas or spots, conferring zebra-like appearance; male pleopod 1 exopod sub-rectangular, lateral process not developed, outer distal margin serrate near indentation ........................................................ I. zebricolor Leistikow, 1999 ( Leistikow 1999: pls 1-5).

2. Male pereopods 1-3 carpus strongly enlarged, sometimes pereopod 4 carpus ............................................. 13

— Male pereopods 1-3 carpus not enlarged ..................................................................................................... 3

3. Male pereopod 7 merus without lobe .......................................................................................................... 4

— Male pereopod 7 merus with proximal lobe ........... I. curvaculeus Leistikow, 2001 ( Leistikow 2001c: pls 1-5).

4. Male pleopod 1 exopod with lateral process directed outwards (surpassing outer margin) ............................ 5

— Male pleopod 1 exopod without lateral process directed downwards (or not surpassing outer margin) ...... 10

5. Dactylar seta surpassing outer claw and apically plumose ............................................................................ 6

— Dactylar seta not surpassing outer claw and apically pointed .......................................................................... ............................................................................... I. fasciifrons Leistikow, 2001 ( Leistikow 2001b: figs 1-4).

6. Male pereopod 7 ischium with rounded depression on rostral surface ......................................................... 7

— Male pereopod 7 ischium without rounded depression on rostral surface .................................................... 8

7. Male pereopod 7 ischium with short rounded depression on rostral surface; male pleopod 1 exopod with lateral process well developed and obliquely directed outwards, endopod with reduced subapical outer lobe ............ ....................................................................... I. plurimaculata Leistikow, 2000 ( Leistikow 2000: figs 12-16).

— Male pereopod 7 ischium with wide rounded depression on rostral surface; male pleopod 1 exopod with lateral process reduced and laterally directed outwards, endopod with developed subapical outer lobe ...................... ................................................................... I. perijaensis Carpio-Díaz, López-Orozco & Campos-Filho n. sp.

8. Male pereopod 2 carpus with dense field of setae of about half of its width; male pleopod 1 exopod with lateral process directed outward, downwards or reduced ........................................................................................ 9

— Male pereopod 2 carpus with dense field of setae of about one quarter of its width; male pleopod 1 exopod with lateral process obliquely directed outwards and distal margin rounded ........................................................... .................................................................. I. bolivari Vandel, 1968 ( Leistikow & Schmidt 2002: figs 22-27).

9. Male pleopod 1 exopod with lateral process directed outwards and distal margin straight ............................... ............................................................................... I. muelleri Leistikow, 1997 ( Leistikow 1997: figs 14-19).

— Male pleopod 1 exopod with lateral process obliquely directed outwards and distal margin rounded .............. ............................................................................. I. cadoangelis Leistikow, 2000 ( Leistikow 2001b: figs 1-6).

10. Male pleopod 2 endopod slightly longer than exopod ............................................................................... 11

— Male pleopod 2 endopod twice as long as exopod ............... I. andina ( Vandel, 1968) ( Vandel 1968: fig. 11).

11. Male pereopod 7 ischium with fringe of setae on sternal margin ............................................................... 12

— Male pereopod 7 ischium without fringe of setae on sternal margin ............................................................... ......................................................................... I. stenocarpa Schmalfuss, 1980 ( Schmalfuss 1980: figs 9-14).

12. Cephalon with frontal line marked; maxilla subequal lobes; pereopods 1 and 2 merus and carpus with dense field of setae; dactylar seta apically enlarged, conferring spatuliform-like appearance; male pleopod 1 endopod without subapical lobe .......... I. amazonica Lemos de Castro, 1965 ( Leistikow & Schmidt 2002: figs 17-21).

— Cephalon without frontal line well-marked; maxilla outer lobe wider than inner lobe; pereopod 2 merus and carpus without dense field of setae; dactylar seta apically plumose; male pleopod 1 exopod with lateral process rounded, endopod with short subapical lobe ............ I. unicartagenae Campos-Filho, Carpio-Díaz & López-Orozco n. sp.

13. Male pereopod 1-2 or 1-3 carpus enlarged ................................................................................................ 17

— Male pereopod 1 carpus enlarged .............................................................................................................. 14

14. Male pereopod 7 ischium with distal sternal portion prominent ................................................................ 15

— Male pereopod 7 ischium with distal sternal portion not prominent ......................................................... 16

15. Dactylar seta apically enlarged, conferring spatuliform-like appearance; male pereopod 7 ischium with sternal margin concave and rounded depression on rostral surface ... I. parie Leistikow, 2001 ( Leistikow 2001b: figs 13-16).

— Dactylar seta apically plumose; male pereopod 7 ischium with sternal margin straight and lobe bearing one strong setae on caudal surface ......................... I. herrerai López-Orozco, Carpio-Díaz & Campos-Filho n. sp.

16. Male pereopod 7 ischium with sternal margin concave bearing dense fringe of thin setae; male pleopod 1 exopod with lateral process directed downwards, endopod with distal portion sinuous ............................................... ............................................................................ I. irmleri Schmalfuss, 1980 ( Schmalfuss 1980: figs 27-31).

— Male pereopod 7 ischium with sternal margin sinuous and without fringe of thin setae; pleopod 1 exopod with lateral process not developed, endopod with distal portion straight ................................................................ ................................................................. I. sturmi ( Vandel, 1972) ( Leistikow & Schmidt 2002: figs 11-16).

17. Male pereopod 1-2 carpus enlarged (sometimes male pereopod 3 carpus slightly enlarged) ....................... 18

— Male pereopod 1-3 carpus enlarged ........................................................................................................... 23

18. Male pleopod 1 exopod with lateral process directed outwards (surpassing outer margin), endopod with subapi- cal lobe ...................................................................................................................................................... 19

— Male pleopod 1 exopod with lateral process directed downwards, endopod without subapical lobe ................ ....................................................................... I. longicauda Schmalfuss, 1980 ( Schmalfuss 1980: figs 21-26).

19. Male pereopod 7 ischium with distal sternal portion prominent ................................................................ 20

— Male pereopod 7 ischium without distal sternal portion prominent .......................................................... 22

20. Dactylar seta longer than outer claw and apically plumose ........................................................................ 21

— Dactylar seta shorter than outer claw and apically acute ................................................................................. ............................................................................. I. marmorata Leistikow, 2000 ( Leistikow 2000: figs 7-11).

21. Maxilla outer lobe wider than inner lobe; male pereopod 3 carpus with wide field of setae reaching half of its width; male pereopod 7 ischium with distal sternal portion distinctly prominent ........................................... .............................................................................. I. guamae Leistikow, 2001 ( Leistikow 2001b: figs 17-20).

— Maxilla with lobes subequal width; male pereopod 3 carpus with wide field of setae in almost all its width; male pereopod 7 ischium with distal sternal portion slightly prominent ................................................................. ............................................................................... I. mineri (Van Name, 1936) ( Leistikow 2001d: figs 1-4).

22. Cephalon with frontal line not well marked; maxilla with lobes subequal in width; male pereopod 3 carpus with wide field of setae of about one quarter of its width; male pleopod 1 exopod with distal margin straight ........ ............................................................................... I. elongata Leistikow, 1997 ( Leistikow 1997: figs 20-25).

— Cephalon with frontal line well marked; maxilla outer lobe wider than inner lobe; male pereopod 3 carpus slightly enlarged, wide field of setae of about half of its width; male pleopod 1 exopod with distal margin rounded ... ................................................................................. I. martinae Leistikow, 1997 ( Leistikow 1997: figs 8-13)

23. Male pereopod 4 carpus enlarged, dense field of setae covering almost all carpus width; male pereopod 7 ischium with distal sternal portion slightly prominent ..... I. quadrispinis Leistikow, 2000 ( Leistikow 2000: figs 17-22).

— Male pereopod 4 carpus not enlarged; male pereopod 7 ischium with distal sternal portion prominent or not prominent ................................................................................................................................................. 24

24. Male pleopod 1 exopod with lateral process directed downwards ............................................................... 25

— Male pleopod 1 exopod with lateral process directed outwards .................................................................. 27

25. Male pereopods 1-3 carpus enlargement and wide field of setae progressively decreasing; male pereopod 7 ischium with distal margin strongly prominent or not prominent ................................................................ 26

— Male pereopods 1-3 carpus strongly enlarged; male pereopod 7 ischium with distal margin strongly prominent bearing distinct brush of thin seate ......................... I. panamensis Leistikow, 1999 ( Leistikow 1999: figs 6-9).

26. Cephalon with frontal line well marked; male pereopod 7 ischium with sternal margin concave and distal sternal portion not prominent .................................. I. hanagarthi Schmalfuss, 1980 ( Schmalfuss 1980: figs 15-20).

— Cephalon with frontal line not well marked; male pereopod 7 ischium with sternal margin straight and concave depression on rostral surface .................................... I. colorata Leistikow, 2001 ( Leistikow 2001b: figs 9-12).

27. Male pereopod 7 ischium with distal sternal prominence triangular; male pleopod 1 endopod with apical portion directed downwards ........................................................................................................................... 28

— Male pereopod 7 ischium with distal sternal prominence rounded; male pleopod 1 endopod with apical portion slightly bent outwards ........................................ I. trifasciata Leistikow, 2001 ( Leistikow 2001b: figs 21-24).

28. Male pereopod 6 merus with proximal portion swelled, conferring a lobe aspect; male pereopod 7 ischium without depressions on rostral surface; male pleopod 1 endopod with triangular subapical lobe directed downwards ...................................................................... I. variegata (Dollfus, 1893) ( Leistikow 1997: figs 27-32).

— Male pereopod 6 merus not swelled on proximal portion; male pereopod 7 ischium with two rounded depressions on rostral surface; male pleopod 1 endopod with triangular subapical lobe directed upwards ................. ................................................................................... I. hirsuta Leistikow, 2001 ( Leistikow 2001b: figs 5-8).