Isometrus nakshatra, Sulakhe & Deshpande & Gowande & Dandekar & Ketkar, 2022

Sulakhe, Shauri, Deshpande, Shubhankar, Gowande, Gaurang, Dandekar, Nikhil & Ketkar, Makarand, 2022, Arboreal gems: resurrection of Isometrus sankeriensis Tikader & Bastawade, 1983 and descriptions of two new species of Isometrus Ehrenberg, 1828 (Scorpiones: Buthidae) from the Western Ghats, India, European Journal of Taxonomy 811 (1), pp. 1-50 : 21-27

publication ID	https://doi.org/ 10.5852/ejt.2022.811.1725
publication LSID	lsid:zoobank.org:pub:4EAB19E4-9B7A-48DC-88ED-C15CE31EC96D
DOI	https://doi.org/10.5281/zenodo.6454215
persistent identifier	https://treatment.plazi.org/id/E3BBB5E4-8A30-40DD-9BBD-731046A22232
taxon LSID	lsid:zoobank.org:act:E3BBB5E4-8A30-40DD-9BBD-731046A22232
treatment provided by	Felipe
scientific name	Isometrus nakshatra
status	sp. nov.

Treatment

Isometrus nakshatra View in CoL sp. nov.

urn:lsid:zoobank.org:act:E3BBB5E4-8A30-40DD-9BBD-731046A22232

Figs 8–12 View Fig View Fig View Fig View Fig View Fig , 18B View Fig , 19B, E View Fig , 21B View Fig , 23B View Fig , 25B View Fig ; Table 2

Diagnosis (♂ ♀)

Total length 38.60–48.69 mm. Base colouration blackish-brown and variegated with brown-yellow stripes and spots; appendages yellowish with blackish-brown stripes and spots. Basal segments of chelicerae dorsally dark brown with blackish reticulation. Pectinal tooth number 15–16 in both sexes. Median supra-ocular region with fine and dense granulation. Median ocelli anteriorly situated in ratio of 1: 1.9. Tergites I–VI sparsely and coarsely granular, with median carina stronger on posterior region. Isometrus nakshatra sp. nov. differs from all other Indian species of Isometrus based on the following set of morphological characters:

1. Surface of carapace with mixed granulation with fine and dense granulation in median supra-ocular region ( Figs 9C View Fig , 18B View Fig ) as opposed to: coarsely and sparsely granular with some areas without granules in I. sankeriensis and I. thurstoni ; finely and densely granular in I. amboli ; coarsely and densely granular in I. tamhini ; granular throughout with mixed granules, more densely granular in inter-

ocular area and median posterior ocular area in I. kovariki ; and granular throughout but obsolete in I. maculatus .

2. Chela length to width ratio in males 10.6 as opposed to 6.1–6.5 in I. tamhini , 5.3–5.9 in I. amboli , 5.7–5.8 in I. sankeriensis , 5.1–6.4 in I. kovariki and 5.0– 5.2 in I. thurstoni ; in females 6.1–6.2 as opposed to 5.2–5.9 in I. tamhini , 5.7 in I. amboli and 4.8 in I. kovariki ( Tables 1–3 View Table 1 ).

3. Lateral patches on mesosomal tergites V and VI with fine granulation along margins ( Fig. 21B View Fig ) as opposed to coarse granulation along margins in I. tamhini .

4. Metasomal length to carapace length ratio in males 5.3–5.8 as opposed to 8.8–9.1 in I. tamhini , 7.2–8.8 in I. amboli , 5.9–6.1 in I. sankeriensis , 7.6–8.2 in I. thurstoni , 6.5–7.3 in I. kovariki and 9.6 in I. maculatus ( Tables 1–3 View Table 1 ).

5. Lateral supramedian and ventral lateral carinae on metasomal segments II–IV moderately granular ( Fig. 23B View Fig ) as opposed to strongly granular in I. tamhini and I. sankeriensis .

6. Telson length to width ratio in males 3.5–4.1 as opposed to 4.6–4.8 in I. tamhini and 4.3 in I. sankeriensis ( Tables 1–3 View Table 1 ).

7. Ventral median carina of telson vesicle weakly granular ( Fig. 19E View Fig ) as opposed to moderately granular in I. amboli and strongly granular in I. tamhini .

8. Spiniform granules of promedian carina of pedipalp patella weakly developed as opposed to moderately developed in I. tamhini , I. amboli , I. sankeriensis and I. kovariki , and strongly developed in I. thurstoni ( Figs 24–25 View Fig View Fig ).

For comparisons of I. nakshatra sp. nov. with I. wayanadensis sp. nov., described below, refer to the diagnosis section of the latter.

Etymology

The species epithet is a noun in apposition, derived from the Kannad word ‘nakshatra’ (= ‘star’). It refers to the star-shaped fort named ‘Manjarabad’, very close to the type locality. The fort was built in 1792 by Tipu Sultan, the then ruler of Mysore, using French military architects. The sultan wanted to build a highway between Mangalore and Coorg for his expansion programs. As he was allied with the French at that time against the British, he sought the help of French engineers to build this fort in European style.

Material examined

Holotype INDIA • ♂, adult; Karnataka State, Hassan District, Sakleshpur, Kadmane Tea Estate ; 12.89° N, 75.68° E; 911 m a.s.l.; 2 Nov. 2020; Makarand Ketkar, Shubhankar Deshpande, Shauri Sulakhe and Swayam Thakkar leg.; BNHS SC 195 View Materials . GoogleMaps

Paratypes INDIA • 1 ♂, adult; same collection data as for holotype; INHER 275 GoogleMaps • 1 ♀, adult; same collection data as for holotype; INHER 276 GoogleMaps • 1 ♀, adult; same collection data as for holotype; BNHS SC 196 View Materials GoogleMaps .

Description (holotype, ♂, measurements in Table 2)

COLOURATION ( Fig. 8A–B View Fig ). Body blackish brown and variegated with brownish yellow stripes and spots; appendages yellowish with blackish brown stripes and spots; metasomal segment V dark brownish to blackish, darker on posterior portion; pedipalp fingers dark brownish. Ventral portion uniformly brown and sternite VII with a few dark spots. Basal segments of chelicerae dorsally dark brown with blackish reticulation, ending anteriorly in a blackish transverse patch. Fingers of chelicerae dark brown with tip of fingers black. Telson yellowish-brown.

CARAPACE ( Figs 9C View Fig , 18C View Fig ). Surface of carapace with mixed granulation. Carapace without carinae. Median supra-ocular area finely granular. Inter-ocular area with coarse and dense granules. Pair of median ocelli

situated anteriorly, with median ocelli to anterior margin/median ocelli to posterior margin ratio of 1: 1.9. Antero-lateral ocular tubercle granular with type 5 lateral ocelli. Three pairs of large major ocelli and two small minor ocelli situated behind major ocelli. Longitudinal furrow shallow. Anterior margins finely granular. Lateral margins weakly crenulated below lateral ocelli. Posterior margin almost entirely smooth.

CHELICERAE ( Fig. 8C View Fig ). Characteristic of Buthidae . Basal segments and movable fingers with short and firm setae on basal and ventral surfaces.

PEDIPALP ( Figs 10 View Fig , 25B View Fig ). Femur with five carinae (prodorsal, retrodorsal, promedian, retromedian and proventral). All carinae crenulated. Intercarinal surfaces weakly granular except ventral surface smooth with a few fine granules on proximal portions. Patella with seven distinct carinae (dorsomedian, prodorsal, retrodorsal, retromedian, retroventral, promedian and proventral). Intercarinal surfaces weakly granular on dorsal surface and smooth on ventral surface. Chela with four carinae (dorsomedian, dorsoretrosubmedian accessory, retromedian and retroventral). Fixed fingers with two smooth dorsal median and retrodorsal carinae. Movable and fixed fingers with six rows of prolateral and retrolateral denticles in pairs and one additional single row of retrolateral denticles on proximal portion.Trichobothrial pattern typical for genus (chela dorsal 12, chela ventral 2, patella dorsal 6, patella retrolateral 7, femur dorsal 7 and femur prolateral 4).

LEGS ( Figs 8A–B View Fig , 9A–B View Fig ). Femur and patellae carinated. All carinae granular. Tibia 3 and 4 without tibial spurs. All legs with pair of pedal spurs. Tarsomere covered with long delicate setae arranged in parallel rows on ventral side. Tarsomere I (basitarsus) with a tuft of short, stout blackish setae on ventral side. Tarsomere II (telotarsus) compressed laterally and ventrally, with paired row of short, pointed, anteriorly directed, closely placed setae.

GENITAL OPERCULUM ( Fig. 8C View Fig ). Wider than long, elliptical, separated with a pair of short male genital papillae.

PECTINES ( Fig. 8C View Fig ). Basal piece rectangular, notched on anterior median margin. Posterior margin of basal piece curved. Marginal lamella of 3/3 digits and median lamella of 7/7 digits, outer margin armed with a row of stout, short red setae and a few setae on surface. Fulcra 14/14, very small, roughly triangular, each armed with a few short red setae, placed in between adjacent pectinal teeth. Teeth 15/15, strong and stout.

MESOSOMA ( Figs 8A–B View Fig , 9A–B View Fig , 21B View Fig ). Tergites I–VI sparsely and coarsely granular with median carina more strongly developed on posterior side. Posterior and lateral margins granular. Lateral patches on mesosomal tergites V and VI with fine granulation along margins. Tergite VII granular, narrowed posteriorly, with two pairs of lateral granular carinae. Broad median carina present, more strongly developed on anterior portion. Sternites III–V almost entirely smooth, with a pair of spiracles. Sternite VI finely granular on lateral portion. Sternite VII entirely granular, more closely granular on lateral portion; two pairs of granular carinae, with median carina present on posterior portion and lateral carina present only on anterior half.

METASOMA ( Figs 8A–B View Fig , 9A–B View Fig , 23B View Fig ). All segments longer than wide. Segments I–IV with four pairs of carinae (dorsal lateral, lateral supramedian, ventral lateral, ventral submedian). Intercarinal surfaces almost smooth. Lateral supramedian and ventral lateral carinae on segments II–IV moderately granular. Lateral inframedian carina weakly developed on distal portion of segments III and IV. Dorsal lateral carina on segments I–IV ending in very weak tubercles. Segment V with five carinae (lateral supramedian pair, ventral lateral pair and single ventral median). Intercarinal surfaces granular. Anal rim granular.

TELSON ( Fig. 19B, E View Fig ). With stout vesicle, smooth on dorsal surface. Ventral median carina weakly granular, ending in triangular, subaculear, pointed nodule, armed with a pair of minute denticles on inner basal margin. Ventral portion with two weak carinae. Lateral and ventral intercarinal surfaces weakly granular. Aculeus strongly elongated.

Distribution, habitat and ecology ( Figs 12 View Fig , 26 View Fig )

Isometrus nakshatra sp. nov. is only known from its type locality, Kadmane Tea Estate, Sakleshpur, Hassan District, Karnataka State, India. Specimens were collected from undergrowth and tree bark in a small patch of disturbed evergreen forest on a hill slope adjacent to the crest line of the WG. Unlike other species of Isometrus from India, this new species was also observed in shrubby undergrowth along with tree bark. The forest patch here is disturbed and fragmented due to the infrastructure of the Kadmane tea factory and large scale agriculture (tea, coffee and pepper plantations). The ecology of the new species is congruent with that of bark scorpions.