Isotomurus sahebganjensis, Mandal & Suman & Bhattacharya, 2017

Mandal, G. P., Suman, K. K. & Bhattacharya, K. K., 2017, Five new species of Collembola (Isotomidae) from Jharkhand, India, Records of the Zoological Survey of India 117 (2), pp. 97-112 : 105-106

5. Isotomurus sahebganjensis n. sp.

(Plate 5, Figures 1-19, Table 5)

Material examined: HOLOTYPE: on slide, India: Jharkhand: Dhobijharna under hill stream, Sahebganj district , 22. viii. 2013, Lat and Long. N 25°13’ and E 87°38’, collected by G. P. Mandal, Registration No. 2000/H14/ZSI . PARATYPE: 05 exs in ethyl alcohol, India: Jharkhand: Dhobijharna under hill stream, Sahebganj district, 22. viii. 2013, Lat and Long. N 25°13’ and E 87°38’, collected by G. P. Mandal, Registration No. 2001/H14/ZSI. 01 on slide, India: Jharkhand: Dhobijharna under hill stream, Sahebganj district , 22. viii. 2013, Lat & Long. N 25°13’ and E 87°38’, collected by G. P. Mandal, Registration No. 2002/H14/ZSI .

Description: Body length up to 1.4 mm (excluding appendages).

Colour Pattern: Background colour white. Body devoid of any pigment or patches. Legs, ventral tube and furcular devoid of pigment. Eyes dark blue-black, two black dot present between eyes and median of head. A bluish line present in the posterior side of head. Ant.I, II, III pigmented laterally and Ant.IV pigmented distally (Figure 1).

Head: Eyes 8+8, more or less equal P.A.O rounded or more or less oval, unconstricted, no setae near the base. P.A.O is 1.3 times less than the diameter of nearest omma (Figure 2). Head: Antennae ratio in length as 1.56. Antennal segment ratio in length as I: II: III: IV = 1: 2:

2.1: 2.8. Ant. I with basal sensilla shown in (Figure 3). Ant.III with sensilla shown in (Figure 4). Fourth antennal segment without apical bulb, but pin setae present (Figure 5). Maxillary outer lobe with 5 sublobal hairs (Figure 6).

Thorax and Legs: Ratio of segments of Thorax II: III = 1:

1.14.Thoracic setae smooth &ciliate.Tibio-tarsus with one large macrochaetae present in all legs (Figure 7). Unguis strong, long with two inner teeth, no outer & lateral tooth. Unguis 2.9 times longer than unguiculus. Unguiculus short, no teeth (Figure 8). Tenent hair thin, acuminate and more or less half of unguis (Figure 9). Ventral tube with 6+6 anterior setae (Figure 10). Trochanteral organ with 16 long setae (Figure 11).

Abdomen: Ratio of segments of Abdomen I: II: III: IV: V: VI: 1: 1.1: 1.6: 1.5: 0.7: 0.6. Retinaculaum with 4 teeth & 6 setae in each (Figure 12). Manubrium: mucrodens as 1: 2.2. Manubrium with large no of anterior and posterior setae (Figure 12). Manubrium with large no. of long ciliate setae posteriorly (Figure 13). Dens longer than manubrium and crenulated. Laterally 14-20 ciliate setae arranged in a row on dens (Figure 14). Mucro with 4 teeth but without seta (Figure 15).

Body Chaetotaxy: Body clothed with small to medium and large smooth and ciliate setae on head, thorax and abdomen. Cephalic setae, small to large, ciliate (Figure 16). Thoracic setae small, ciliate and large smooth macrochaetae also present (Figure 17). Abdominal long unilaterally macro-chaetae and multilateral macrchaetae present (Figures 18 and 19).

Ecology: Found under hill stream near Dhobijharna of Sahebganj district, Jharkhand, India.

Etymology: The new species is named after the type locality, Sahebganj, Jharkhand, India.

Remarks: This species belongs to Palustris group having trichobothria 3, 3, 1. Abd. V with 7+7 sensillum, two

Colour pattern Body with distinct colour pattern. Thorax II- Body devoid of any pigment or patches.

Abd. IV with lateral blue black belt present.

Unguis and Unguiculus Unguis with two inner teeth. Unguiculus Unguis with two inner teeth. Unguiculus without tooth. without tooth.

Ventral tube Ventral tube with 4+4 latero- distal setae. Ventral tube with 6+6 anterior setae. Tibiotarsus with macrochaete Tibiotarsus without macrochaetae. Tibiotarsus with one large macrochaetae. Trochanteral organ Trochanteral organ with 11-12 setae. Trochanteral organ with 16 setae. Retinaculum with setae Retinaculum with more than 6 setae. Retinaculum with 6 setae.

Manubrium with setae Manubrium with large no. of anterior setae Manubrium with large no. of posterior setae medial ones elongated, retinaculum with 6+ 6 setae. This species is nearer to Isotomurus dhanbadensis n. sp. In having two inner teeth on claw but strongly differ in colour pattern of Isotomurus dhanbadensis n. sp.

Discussion: The new species from Sahebganj district of Jharkhand, India can easily distinguished from other known species of Isotomurus by claw structure, devoid of pigment, setae on ventral tube and retinaculum and macrochaetae on tibia tarsus. It is close to Isotomurus dhanbadensis n. sp, in having claw with two inner teeth but strongly differ from Isotomurus dhanbadensis n. sp in colour pattern and other characteristics given below in the Table. 5.

Summary

A total of 5 species of Collembola belonging to 2 genera under 2 sub families of family Isotomidae have been described as new to science from the state of Jharkhand, India. The detailed descriptions of each species of Collembola with discussion for difference between closely related species, total numbers of species in the world as well as from India, key to the Indian species and their distribution are also provided.

Importance of Collembola

Collembola play a significant role in the breakdown of leaf litter along with certain other micro-athropods and