Cheiroseius ovalis, Bhattacharyya & Bhattacharyya, 2004

Bhattacharyya, Asit K. & Bhattacharyya, Sisir K., 2004, Two new species of the genus Cheiroseius Berlese, 1916 (Ascidae: Mesostigmata) from the Indian Thar Desert, Zootaxa 403 (1), pp. 1-11 : 3-6

Cheiroseius ovalis sp. nov. ( Figs. 1–8 )

Diagnosis: Dorsal shield with 36 pairs of thick, spinelike setae; all dorsal setae on prominent tubercles; setae J5 simple, setae Z4 longest; sternal shield with conspicuous marking; ventri­anal shield broadly oval, with seven setae; six rows of deutosternal denticles, each row with 7–14 denticles.

Female: Holodorsal shield (448µ long along midline, 264µ wide) highly sclerotized, with dense reticulation, and with 36 pairs of thick, spinelike setae; anterior region with 21 pairs of setae, remaining setae on posterior region of the shield; setae J4–J5, Z5 and S5 are 32µ, 12µ, 36µ and 39µ long respectively; setae Z4 longest (41µ) of all dorsal setae; lateral membrane lineated, with 7 pairs of setae; all setae on dorsal shield borne on prominent tubercles ( Fig. 1 ); peritreme visible dorsally, extending upto beyond setae j1 (16µ); dorsal shield complement of poroids and gland pores difficult to discern amidst ornamentation.

Tritosternum with elongate base, lacinae paired, sparsely plumose ( Fig. 2 ). Sternal shield (88µ long along midline, 166µ wide at level of anterolateral corners) extended anterolaterally, with three subequal (22µ – 24µ) sternal setae; reticulation and conspicuous marking on sternal shield as depicted in fig. 3; metasternal shields large, with metasternal setae (18µ); genital shield finely granulated along posterior margin, truncate posteriorly, widened behind genital setae forming slightly convex lateral margin; hyaline anterior margin of genital shield extending over the region posterior to sternal shield to level of metasternal setae; remnants of endopodal shield present between coxae II–IV; posterior extremities of exopodal­peritrematal shield broad, finely granulated, with several components, curving behind coxae IV; ventral membrane between genital and ventri­anal shield folded, with 5 pairs of setae, including the two pairs posterior to the level of para­anal setae. Peritreme wide, stigmatal opening large, placed at level of anterior half of coxae IV. Ventri­anal shield broadly oval, slightly wider (134µ) than long (120µ), coarsely granulated posteriorly, with 7 simple, subequal (31µ – 32µ) ventral setae; anal opening large; cribrum present in the form of a broad strip behind the post­anal seta.

Epistome trispinate, each spine denticulate, with 2–3 spines each ( Fig. 4 ); hypognathum with short, peglike corniculi; paired corniculi almost parallel to each other; internal malae finely fringed extending upto midlevel of corniculi; six rows of deutosternal denticles, with 7–14 denticles in each row; sixth row widest, discontinuous ( Fig. 5 ); four pairs of simple, subcapitular setae; posterior hypostomatic (26µ) and palpcoxal setae subequal (28µ) but almost half length of anterior hypostomatic setae (52µ); besides simple setae, thornlike and club­shaped setae present on palpal genu and tibia respectively ( Fig. 6 ). Chelicerae damaged, not examined.

All legs with well­developed ambulacra and claws; tibia I slightly shorter (150µ) than tarsus I (160µ); excluding ambulacra, length of legs I–IV as follows: 720µ, 460µ, 420µ and 530µ; tarsus of legs I and II depicted in figs. 7 and 8 respectively; all leg setae smooth; setation of legs I­II­III­IV, respectively: femora 11­10­6­6 and genua 13­10­8­9.

Male: Unknown.

Type: Holotype female, Zoological Survey of India compound, Jodhpur , Rajasthan; ex. decomposed grass litter collected from semi­dried drainage system; 23 March 2003; A.K. Bhattacharyya coll.

Distribution: INDIA: Rajasthan.

Differential diagnosis: The new species, Cheiroseius ovalis differs from all the known species of Cheiroseius in having 7 setae on its ventri­anal shield. The only known other Cheiroseius species which possesses 7 setae on ventri­anal shield is Cheiroseius dromadis ( Evans and Hyatt, 1960) . Besides the above similarity, the new species shows affinities with C. dromadis in having a three­pronged tectum, which is common for most of the Cheiroseius species. C . dromadis shows a number of dissimilarities with the new species, on both dorsal and ventral aspects such as: presence of 37 pairs of pilose dorsal setae; presence of dorsal hump; absence of anterolateral marking on sternal shield; weakly developed tritosternum; shape of metasternal, genital and ventri­anal shield; comparatively longer length of ventral setae; structure of periitrematal shield; longer internal malae (several times longer than that of C. ovalis ); strongly developed ambulacra and presence of club­shaped setae on tarsus II. The new species also shows affinities with C. parbatensis ( Evans and Hyatt, 1960) in having following similarities: number, nature and almost same relative length of dorsal setae, similar shape of tectum, sternal and metasternal shield. However, the new species differs from C. parbatensis in the following aspects: shorter length of setae J4, prominent, characteristic marking on anterolateral edge of sternal shield, shape of genital and ventri­anal shield, number of setae on ventri­anal shield and setation of tarsus II.

Etymology: The species name ovalis has been derived from the broadly oval shape of the ventri­anal shield.

Figures

FIGURE 1: Cheiroseius ovalis sp. nov., female. 1. Dorsum. Scale bar: 50µ.

FIGURE 2–3: Cheiroseius ovalis sp. nov., female. 2. Tritosternum, 3. Venter. Scale bar: Fig. 2, 45µ; Fig. 3, 50µ.

FIGURE 4–8: Cheiroseius ovalis sp. nov., female. 4. Tectum, 5. Gnathosoma, 6. Pedipalp genu and tibia, 7. Tarsus I, 8. Tarsus II. Scale bar: 50µ.