Isotoma Bourlet, 1839

Park, Kyung-Hwa, 2018, Redescription of Isotoma grana Lee, Kim & Kim, 1993 and description of a new species of Isotoma Bourlet, 1839 (Collembola: Isotomidae) from Korea, Zootaxa 4450 (4), pp. 473-480 : 478-479

Key to the Sino-Japanese species of Isotoma Bourlet, 1839

Isotoma gracilliseta Börner, 1909 from Japan is not included in this key because this is believed to belong to the genus Desoria Nicolet, 1842 , by the absence of thickened spine-like manubrial ventroapical setae following the Japanese Collembolan checklist by Yosii (1977). Though authors ( Lee et al. 1993) described the presence of clavate hairs in the original description (but it lacked clavate hairs in the original figure and in my observations based on type specimens), Isotoma grana Lee, Kim & Kim, 1993 from North Korea is included in this key because this species fits well with the characters of the genus Isotoma in having 1) 8+8 ommatidia, 2) PAO small, roundish, shorter than nearest ocellus and 3) manubrial ventroapical setae spine-like.

The following key was modified from Potapov (2001) and Fjellberg (2007), including Isotoma grana .

1 Body without middorsal longitudinal band.................................................................. 2

- Body with middorsal longitudinal band.................................................................... 5

2 Body uniformly coloured............................................................................... 3

- Body with transverse bands.............................................................................. 4

3 Ventroapical manubrial thickening bispinose; posterior side of dens with three macrochaetae................................................................................................. I. anglicana Lubbock, 1862 ; Holarctic

- Ventroapical manubrial thickening simple; posterior side of dens with two macrochaetae... I. viridis Bourlet, 1839 ; Holarctic

4 PAO oblong, much shorter than the nearest ocellus; ventroapical manubrial thickening simple..........................

.................................................................... I. virgata Yosii, 1963 ; Japan & N. Korea - PAO almost rounded, as large as the nearest ocellus; ventroapical manubrial thickening bispinous................................................................................................... I. nishihirai Yosii, 1965 ; Japan

5 Body with broad middorsal longitudinal band............................................................... 6

- Body with fine middorsal longitudinal line.................................................................. 7

6 Apical spines of manubrium serrated................... I. pinnata Börner, 1909 sensu Yosii, 1939, 1963 ; Japan & Korea

- Apical spines of manubrium smooth.......................................... I. riparia ( Nicolet, 1842) ; Palaearctic

7 Head, Ant. I, and Abd. III entirely black............................ I. melanocephala Börner, 1909 ; Japan & N . Korea

- Head, Ant. I, and Abd.III not black....................................................................... 8

8 Abd. IV –VI dark; Abd. VI with serrated unpaired central mesoseta (m0) on dorsal side.................................................................................................. I. grana Lee, Kim & Kim, 1993 ; N. Korea

- Abd. IV –VI not dark; Abd. VI with simple unpaired central microseta (m0) on dorsal side........ I. koreana sp. nov.; Korea