Nannoniscus, G. O. Sars. 1870

Kaiser, Stefanie, Kihara, Terue Cristina, Brix, Saskia, Mohrbeck, Inga, Janssen, Annika & Jennings, Robert M., 2021, Species boundaries and phylogeographic patterns in new species of Nannoniscus (Janiroidea: Nannoniscidae) from the equatorial Pacific nodule province inferred from mtDNA and morphology, Zoological Journal of the Linnean Society 193, pp. 1020-1071 : 1064

KEY TO PACIFIC SPECIES OF NANNONISCUS (BASED ON FEMALE CHARACTERS ONLY)

1. Uropods uniramous ................................................................................................................................................... 2

– Uropods biramous ...................................................................................................................................................... 3

2. Op posterior margin with ≥ 15 setae .............................................................................................................. N. menoti

– Op posterior margin with ≤ nine setae ............................................................................................................ N. ovatus

3. Op without ventral spine ........................................................................................................................................... 4

– Op with ventral spine 1 ................................................................................................................................................ 6

4. Pereonite 2 coxae strongly produced, pereonite 7 with ventral spine......................................................... N. muscarius

– Pereonite coxae 2 not visible in dorsal view, pereonite 7 without ventral spine ............................................................ 5

5. Body length 3.3 pereonite width, pereonites 5–7 anterolateral tergites with setae .................................. N. detrimentus

– Body length 4.5 pereonite width, pereonites 5–7 anterolateral tergites without setae ................................... N. cristatus

6. Plt posterior margin acute ...................................................................................................................... N. acanthurus

– Plt posterior margin rounded...................................................................................................................................... 7

7. Pereonite 2 anterolateral tergite without setae ............................................................................................ N. magdae

– Pereonite 2 anterolateral tergite with setae ................................................................................................................ 8

8. Urp exopodite well developed, endopodite ≤ 3.2 exopodite length..................................................................... N. pedro

– Urp exopodite minute, endopodite ≥ 5.8 exopodite length ............................................................................................ 9

9. Pereonites 3–4 anterolateral tergites without setae....................................................................................... N. perunis

– Pereonites 3–4 anterolateral tergites with setae ........................................................................................................10

10. p posterior margin with ≤ 9 simple setae........................................................................................................ N. hilario

– Op posterior margin with ≥ 14 simple setae ...............................................................................................................11

11. Molar process of left and right Md with ≥ 12 spines distally ........................................................................ N. menziesi

– Molar process of left and right Md with ≤ five spines each.............................................................................. N. brenkei

1 According to Mezhov (1986), the operculum of N. menziesi has a ventral spine, but it was not observed when examining appendages of the type material.