Isotomurus dhanbadensis, 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 : 100-102

2. Isotomurus dhanbadensis n. sp.

(Plate 2, Figures 1-20, Table 2)

Material examined: HOLOTYPE: on slide, India: Jharkhand: Amaghata Forest, Dhanbad, Dhanbad district , 07. ix. 2013, Lat and Long. N 23°49’43.4” and E 86°30’13.3”, collected by G. P. Mandal, Registration No. 1992 /H14/ZSI . PARATYPE: 1 ex on slide, India: Jharkhand: Amaghata Forest, Dhanbad, Dhanbad district , 07.ix.2013, Lat and Long , N23°49’43.4” and E 86°30’13.3”, collected by G. P. Mandal, Registration No. 1993 /H14/ZSI; 09 exs in ethyl alcohol, India: Jharkhand: Amaghata Forest , Dhanbad, Dhanbad district , 07. ix. 2013, Lat and Long, N 23°49’43.4” and E 86°30’13.3” collected by G. P. Mandal, Registration No. 1994/H14/ZSI .

Description: Body length up to 2.7 mm (excluding appendages).

Colour Pattern: Background colour grey to white. Eyes dark blue-black, a line of pigment present between anterior side of two ocelli, median side a long, broad black dot present & remarkably 3+3 ocelli like structure present between the dot, posterior side of head with enlarged pigment patches. Antennae I laterally pigmented with blue-black in one side, Ant.II, III pigmented laterally with deep blue pigment on both sides, Ant. IV totally pigmented. Precoxae, coxae deeply pigmented, rest of the legs unpigmented. Thorax II- Abd. IV with lateral blue black belts present. Dorsally without pigment except Avd. V and VI with narrow stripe present transversely. Furcula unpigmented (Figure 1).

Head: Eyes 8+8, more or less same. 3+3 ocelli- like structure in median of head. (Figure 2). P.A.O oval, egg shaped, two large smooth setae present between the PAO. P.A.O is equal to nearest eye (Figure 3). Antennal segment ratio in length as I: II: III: IV = 1: 1.8: 1.9: 2.1. Fourth antennal segment without apical bulb, a big pin seta but many curved setae & blunt setae present (Figure 4). Third antennal segment with two peg like structure present and many curved setae along with blunt setae (Figure 5). Ant. I with six basal sensilla present (Figure 6). Labrum with 5-7 + 5-7 basomedian setae.

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

0.8. Thoracic setae small, median and large, smooth and ciliate (Figure 7). Tibio-tarsus setae all smooth, no large macrochaetae on tibio-tarsus. Unguis stout and strong, with two inner teeth, no outer and lateral tooth, unguis

2.8 times longer than unguiculus (Figure 8). Unguiculus short, without teeth (Figure 9). Tenent hair thin and acuminate. Ventral tube with 4+4 latero-distal (Figure 10). Trochanteral organ with 11-12 long setae (Figure 11). Abdomen: Ratio of segments of Abdomen I: II: III: IV: V: VI: 1: 1.5: 1.8: 1.4: 0.8: 0.6. Retinaculum with 4 teeth and more than 6 setae in each. Manubrium: dens: mucro 1: 1.9: 0.05. Manubrium with large no of anterior and posterior setae (Figure 12). Manubrium with short, broad several smooth setae (Figure 13). 2/3rd of the dens straight and not crenulated (Figure 14). Dens with numerous lateral setae and few posterior setae (Figure 15). Dens longer than manubrium & crenulate. Mucro with 4 teeth but without seta (Figure 16).

Body Chaetotaxy: Body clothed with small to medium and large smooth and ciliate setae on head, thorax & abdomen. Long ciliate macrochaetae present on abdomen III (Figure 17). Long unilaterally ciliate macro-chaetae present on Abd.V (Figure 18). Cephalic portion with smooth setae. Abd. VI with 4+4 large macrochaetae present (Figure 19). Abdomen V with 7+7 sensilla, two medial ones elongated (Figure 20).

Ecology: Found under thick bed of leaf litter of Amaghata Forest, Dhanbad district, Jharkhand, India.

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

Remarks: This species has remarkable 3+3 ocelli like structure on median of the head along black long, broad dot present. This species belongs to Palustris group having trichobothria 3, 3, 1. Abd. V with 7+7 sensillum, two medial ones elongated, retinaculum with more than 6 setae. Inner tooth on the claw, seta and lamella on the mucro variable.

Discussion: The new species from Dhanbad district of Jharkhand, India can easily distinguished from other known species of Isotomurus by colour pattern, 3+3 ocellilike structure in median of head, claw structure, setae on ventral tube and retinaculum. It is close to Isotomurus viridipalustris Kos, 1938 , in having claw with two inner tooth in distal half and mucro without seta but strongly differ from Isotomurus viridipalustris in colour pattern and other characteristics given below in the Table 2.