Isotoma grana Lee, Kim & Kim, 1993

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 : 476-477

Isotoma grana Lee, Kim & Kim, 1993

( Figures 22–25 )

Specimens examined. holotype and 5 paratypes (3 paratypes remount): N. KOREA, Myohyangsan (Mt.), Pyunganbuk-do Province, Collection No. 782, July 1982.

Type specimens are deposited in the National Institute of Biological Resources ( NIBR), Incheon, Republic of Korea , and the Insect Collection , Department of Biology Education , Chonbuk National University, Jeonju, Korea ( ICCU) .

Redescription. Body length up to 0.9 mm. Body shape as common for the genus. Abd. V and VI separate. Anal valves as spine-like papillae. General colour of body greyish yellow, mottled with blue pigment randomly dispersed in alcohol. Head with a dark spot in center.

Head. Eye patch black, with 8 ocelli on each side, G and H smaller. PAO roundish, shorter than diameter of nearest ocellus. Ant I with a few ventral sensilla. Ant. II–III with many hair-like sensilla on dorsal side. Ant. III organ normal. Ant. IV with numerous hair-like sensilla, without apical bulb, with simple or bifurcate subapical pinchaeta and short rod-shaped subapical organite in a pit. Labrum 4/554, with four apical folds, lateral folds larger than median pair. Frontoclypeal area with 15 chaetae. Maxilla with short unmodified lamellae. Maxillary palp bifurcate with 4 sublobal setae. Labium with 4 proximal and 7–11 basomedian setae, and guards; guard e7 present.

Body chaetotaxy. Very similar to Isotoma koreana sp. nov., in the plurichaetotic body chaetae. Ordinary chaetae varying lengths and thickness abundant. Macrochaetae long and moderately serrated ( Fig. 22 ). Macrochaetae on Abd. I–VI as 3,3,3,3,5,4. Median macrochaeta on Abd. V shorter than 5 times of length of inner claw III. Unpaired central chaeta on dorsal side of Abd. VI (m0) serrated mesochaeta ( Fig. 23 ). Mesochaetae on Th. II–Abd. I often hardly distinguished from macrochaetae in large specimens. Sensillary chaetotaxy of Th. II–Abd. IV as 66/5556, including 11/111 spine-like microsensilla. All posterior setae on anal valves smooth ( Fig. 24 ).

Appendages. Unguis simple, with 1 pair of lateral teeth and 2 inner teeth. Unguiculus with one corner tooth. Tita with spine-like serrated chaetae along inner edge, stronger on leg III; without clavate hairs, tenant hairs pointed; apical whorl has 8 setae. Ventral tube with 9 anterior setae. Retinaculum with 4+4 teeth and 10 setae. Furcula long and tapering, reaching ventral tube. Manubrium with 3–5+3–5 strong, spine-like smooth chaetae in ventroapical position ( Fig. 25 ). Manubrial thickening simple. Dorsal manubrial macrochaeta A shorter than B. Dens long and continuously narrowing, on posterior side with many crenulations. Posterior side of dens with few chaetae, two of which in the basal part are larger. Mucro tridentate.

Remarks. This species is similar to Isotoma koreana sp. nov., in possessing fine middorsal longitudinal band on body and in the plurichaetotic body setae. But it is distinguished by the colour pattern on Abd. IV–VI, the size of PAO, and the unpaired central seta (m0) on dorsal side of Abd. VI: Abd. IV – Abd. VI is dark in I. grana vs. Abd. VI not dark in I. koreana sp. nov.; PAO larger than 1/2 of nearest ocellus in I. grana vs. much smaller than 1/ 2 of nearest ocellus in I. koreana sp. nov., and unpaired central seta (m0) on dorsal side of Abd. VI is serrated mesoseta in I. grana vs. short simple seta in I. koreana sp. nov.

Figures

FIGURES 22–25. Isotoma grana Lee, Kim & Kim: 22, Median macroseta on Abd. V; 23, dorsal chaetotaxy of Abd. VI (arrow indicates unpaired central serrated mesoseta (m0)); 24, ventral chaetotaxy of Abd. VI; 25, apical setae on manubrium (ventral). Scale bar 50 µm (Figs 22–24), 25 µm (Fig. 25).