Isotomurus katule, LAFOORAKI, ELHAM YOOSEFI, HAJIZADEH, JALIL & SHAYANMEHR, MASOUMEH, 2023

LAFOORAKI, ELHAM YOOSEFI, HAJIZADEH, JALIL & SHAYANMEHR, MASOUMEH, 2023, A revision of the genus Isotomurus (Collembola: Isotomidae) in northern Iran using molecular evidence, Zootaxa 5230 (1), pp. 48-66 : 55-58

Isotomurus katule sp. nov. Yoosefi Lafooraki & Shayanmehr

Figs 4–5 , 11b ; Tables 1–3

Type material. Holotype: male on slide, Iran, Golestan province, Aliabad-e katul, Kabudval , forest soil and leaf litter, near creek, 36°53′14″N, 54°53′24″E, 214 m a.s.l., 2019.01.01, leg.: E. Yoosefi Lafooraki. Paratypes: 1 female on slide, 1 in ethyl alcohol, the same data as the holotype .

Description. Body size 1.18–1.48 mm. Body shape as common for the genus. Body uniformly yellow to light brown withoutany bands or patches ( Fig. 4 ).Posterior part of head with large black medial spot. Bases of antennae with dark spots. Antennae dark, Ant. IV darker. Legs and furca paler ( Fig. 4 ). 8+8 ocelli. PAO elliptical, almost as long as the nearest ocellus ( Fig. 5a ). Maxillary outer lobe with 4 sublobal hairs and bifurcate palp. Labrum with 4 prelabral setae, labral edge as common for the genus, with four sharp ridges and ventro-apical ciliation. Labium with 5+5 basomedian and 3 proximal setae. Antennae about 1.7 as long as head diagonal. Antennal III organ with two thick inner sensilla and several slender sensilla ( Fig. 5d ). Ant. IV with a subapical pin seta and some and several short blunt lateral sensilla ( Fig. 5c ).

Body covered with finely ciliated setae of unequal length ( Fig. 5e ). Claw with a pair of small lateral tooth and one inner tooth. Ret. with 4+4 teeth and 5–8 setae. VT with 3+3 laterodistal and many anterior and posterior setae. Manubrium densely covered by setae, dorsal side with mesosetae and ventral side with smooth setae which are longer at distal margin. Manubrial thickening simple, without teeth in medial part. Dens rather slender, continuously narrowed, with a sparse cover of dorsal setae, in basal 1/3 only. Posterior side of dens crenulated (as in I. hyrcanicus , Fig. 11a ). Mucro with four teeth, without setae or lamellae. Apical tooth small ( Figs 5b , 11b ). Ratio manubrium: dens: mucro as 16.25: 27.75: 1. Ratio of mucro to outer edge of claw III as 0.3. Modified male setae on Abd. III and IV absent.

Etymology. The new species is named after the ethnicity of the people living in the type locality, Aliabad-e katul. The Katuls are the people of Iranian descent who constitute the main natives living in the Aliabad-ekatul region.

Ecology. It is the inhabitant of woodland forests along waters.

Discussion and remarks. Results of the molecular analyses confirm the specific status for population which is described here as a new species. The genetic divergence between I. katule sp. nov. and the other species of the genus is ranging from 12.3% to 33.1% ( Table 2 ).

The new species is related to Isotomurus species with 3,3,1 Trich. on Abd. II, III and IV, 3+3 laterodistal setae on VT, and uniform body color. Main differences between I. katule sp. nov. and these species are summarized in Table 1 . The new species is close to I. italicus . Apart from above mentioned characters, their body size is similar (less than 2 mm). But they can be distinguished by different macrosetae on abdomen (long and strongly ciliated in I. katule sp. nov. and short and smooth in I. italicus ), different number of setae on Ret. (8–10 in I. italicus and 5–8 in I. katule sp. nov.), PAO to ocellus ratio (1.4 in I. italicus and 1.0 in I. katule sp. nov.), and modified male setae (present on Abd. IV in I. italicus and absent in I. katule sp. nov.). They differ in ecology: I. italicus is collected often in disturbed habitats like gardens and farmlands which are not very wet ( Fjellberg, 2007), while I. katule sp. nov. lives in deep forests along water.

The new species is near to I. fucicola by presence of 3+3 laterodistal setae on VT, long ciliated Mac. on abdomen, uniform body color, and similar habitats. They can be separated by different number of setae on Ret. (8–11 in I. fucicola and 5–8 in I. katule sp. nov.), PAO to ocellus ratio (1.5 in I. fucicola and 1 in I. katule sp. nov.), body size (1.7–2.5 mm in I. fucicola and 1.18–1.48 mm in I. katule sp. nov.), and modified male setae (present on Abd. III and IV in I. fucicola and absent in I. katule sp. nov.). Genetic divergence among them is 28.0% for COI gene ( Table 2 ).

Isotomurus katule sp. nov. is closely related to I. graminis . They can be distinct by body size (more than 2.5 mm in I. graminis and less than 1.5mm in I. katule sp. nov.), and modified male setae (present on Abd. III and IV in I. graminis and absent in I. katule sp. nov.). They are different ecologically and genetically. I. graminis usually inhabits in humid open grasslands and is rare in forests and along waters, in contrast, I. katule sp. nov. can be found along water in forest. Genetic divergence among them is 29.9% for COI gene ( Table 2 ).

The new species is related to I. cassagnaui . They share body size less than 1.5 mm, PAO to ocellus ratio near 1, 5 setae on Ret., and few basomedian setae (about 5) on labium. Both species are found near water. They differs in modified male setae (present on Abd. III and IV in I. cassagnaui and absent in I. katule sp. nov.), blue spots on lateral sides of Abd. VI (present in I. cassagnaui and absent in I. katule sp. nov.), antennal segment ratio I: II: III: IV (1: 0.6: 0.60: 0.50 in I. cassagnaui and 1: 0.47: 0.40: 0.34 in I. katule sp. nov.), Mac. on abdomen (relatively short and not densely ciliated in I. cassagnaui and long and strongly ciliated in I. katule sp. nov.). The genetic divergence between them is 23.1% for COI gene which supports that our specimens are a different species.

This species is likely mixed up with other species with uniform body color in previous records.

Figures

FIGURE 4. Isotomurus katule sp. nov.: Body color

FIGURE 5. Isotomurus katule sp. nov.: (a) ocelli and PAO (scale: 20μm); (b) mucro (scale: 20μm); (c) Ant. IV sensilla (shown by asterisks) and pin seta (shown by arrow) (scale: 5μm); (d) Antennal III organ (scale: 10μm); (e) Abd. VI Mac. and Trich. (scale: 100μm).

FIGURE 11. (a) dens, lateral view in Isotomurus hyrcanicus sp. nov. (scale: 50μm); (b) mucro in Isotomurus katule sp. nov. (scale: 10μm); (c) basomedian and proximal setae of labium in Isotomurus potapovi sp. nov. (scale: 10μm).

Tables

TABLE 2. Intraspecific and interspecific genetic divergences among species based on K2P distances percentages for COI (1: Isotomurus hyrcanicus sp. nov.; 2: I. potapovi sp. nov.; 3: I. katulesp. nov.; 4: I. punctiferus; 5: I. unifasciatus; 6: I. maculatus; 7: I. graminis; 8: I. fucicola; 9: I. cassagnaui; 10: I. palustris; 11: I. afghanicus)

species	Intraspecific divergence	1	2	3	4	5	6	7	8	9	10
1	0.3
2	0.7	22.4
3	--	27.1	20.7
4	1.8	26.7	29.7	33.1
5	0	24.4	29.3	27.0	33.3
6	--	25.5	26.3	29.6	29.2	28.8
7	0.2	24.3	24.2	29.9	30.6	29.9	27.1
8	--	29.8	22.5	28.0	28.6	27.3	25.0	28.0
9	0.4	26.1	22.3	23.1	30.4	28.1	28.3	26.4	22.0
10	0.1	29.8	27.7	31.0	28.7	25.5	23.0	27.6	28.0	28.0
11	--	25.3	17.4	12.3	29.6	25.1	24.3	23.5	22.2	25.3	27.3