Ameroseius sternalis, Bhattacharyya & Kheto, 2015

Bhattacharyya, A. K. & Kheto, S., 2015, A new species of Ameroseius (Mesostigmata: Ameroseiidae) from India, Acarologia 55 (3), pp. 297-301 : 298-300

Ameroseius sternalis n. sp.

( Figures 1-2 )

Diagnosis — Anterior margin of holodorsal shield densely denticulate. Four pairs of small lateral marginal setae (r4, r5, R1 and R5); setae r6 long, narrow, leaf-like. Female without any metasternal shield; setae st3 placed on soft membrane. Male with three pairs of medioventral setae (Jv1, Jv2 and Jv3) on ventri-anal shield. Opisthogastric membrane of female and male with one and three pair of pores respectively. Ventri-anal shield of male with paired pores. Setae s2, r5, r6, R1, R5 and Z5 setae raised on tubercles.

Material examined — Holotype ♀, India, West Bengal, Sitala , 22°25.769’N, 88°26.791’E; nest of Lesser Banded Hornet, Vespa affinis (Linnaeus, 1764) ; 9 November, 2014; B. Sanfui coll. Paratypes: 5 ♀♀, 2 ♂♂, collection data same as in holotype. 2 ♀♀, India, West Bengal, Hoogly, Harihar , 22°50.118’N, 87°57.449’E; soil under grass; 8 November, 2014; S. Kheto coll. 2 ♂♂, India, West Bengal, Purulia, Bondi Village , 23°07.092’N, 86°13.906’E; soil; 8 March, 2015; S. Kheto coll.

Female: Dorsum ( Fig. 1A ) — Holodorsal shield 321 – 385 µm long and 207 – 237 µm wide, heavily sclerotized, ornamented, with 29 pairs of setae, podonotal and opisthonotal region with 18 and 11 pairs of setae respectively; setae r4, r5, R1 and R5, being spine-like differs from other finely serrated dorsal setae; setae s2, r5, r6, R1, R5 and Z5 setae raised on tubercles; length of dorsal setae are represented in Table 1. Anterior margin of dorsum, extending upto setae s2, with its distinct shape made by irregular denticle-like structures.

Venter ( Figs. 1 B-F) — Tritosternum small, with marginally pilose laciniae; length of tritosternal base and laciniae almost equal. Sternal shield smooth, 63 µm long, 90 µm wide, with st1 and st2; st3 placed on soft membraneous integument; st1 shortest (10 µm long), setal length of st2-st5 varies between 16 µm and 19 µm. Genital shield smooth, posteriorly concave, 120 µm long, 83 µm wide, st5 placed on postero-lateral margins. Anal shield wider (110 µm) than long (90 µm), distinctly reticulated, with paired para- and a post-anal setae; cribrum restricted to a small posteriormost area of the shield.

Opisthogastric soft integument with five pairs of simple seate, four of them placed between genital and anal shield, setae Jv5 placed close to posterior margin of idiosoma; metapodal shields paired, oval. Anterior section of peritreme reaching beyond anterior margin of coxae I; stigmata placed beside coxae IV; terminal part of peritrematal shields moderately widened and reaching beyond coxae IV.

Hypostomal groove narrow; denticles not obviously discernible; shape of tectum as in Fig. 1C ; corniculi bifid, weakly sclerotized; all setae simple. Palp apotele two-tined. Cheliceral fixed digit tridentate, movable digit edentate ( Fig. 1D ); pilus dentilis short and simple.

Legs I-IV with claws and ambulacra; setae on legs simple to pilose ( Figs. 1 E-F); length (excluding ambulacra) of legs I-IV: 277 µm, 222 µm, 205 µm and 259 µm.

Male ( Figs. 2 ): Dorsal shield entire, 267 – 291 µm long and 168 – 188 µm wide, ornamented as in female, dorsal setae similar to those as in female, length of dorsal setae represented in Table 1, setae J2 comparatively longer than those of female ( Fig. 2A ).

Sterniti-genital shield oblong, 170 µm in length and 73 µm in width, reticulation weak or not properly discernible, with five pairs of setae (st1, st2, st 4 – 12 µm; st3, st 5 – 10 µm). Peritrematal shield posteriorly comparatively wider but shorter than that of female ( Fig. 2B ). Metapodal shield shorter and more ovoid than in female.

Ventri-anal shield 340 µm long and 282 µm wide, delicately reticulate, with Jv2, Jv3 and Zv2 of equal length (8 µm), paired para- and a post-anal setae of uniform length (19 µm), with one pair of pore. Opisthogastric membrane reticulated as delineated in Fig. 2B , with three pair of pores and two pairs of setae (10 µm).

Legs I-IV with pulvilli and claws, 247 µm, 210 µm, 193 µm and 249 µm long respectively, leg chaetotaxy same as in female.

Hypostomal groove narrow, deutosternal denticles not properly discernible; corniculi, setae same as in female. Chelicerae weakly developed, fixed digit unidentate, movable digit without any tooth, spermatodactyl short, wide.

Etymology — The specific epithet, i.e., sternalis , refers to the characteristic shape of sternal shield.

Differential diagnosis — The new species, Ameroseius sternalis superficially resembles to Ameroseius corbiculus (Sowerby, 1806) in the nature of setae as well as shape of ventri-anal shield but greatly differs from A. corbiculus in the following aspects: absence of foliately widened vertical setae j1, distinctive anterior body margin, shape of tectum, absence of sub-oval platelets containing st3 setae and exopodal shield. However, the new species can be differentiated from all other known species by the characteristic shape of sternal shield.

Figures

FIGURE 1: Ameroseius sternalis n. sp., female: A – Dorsum; B – Venter; C – Tectum; D – Chelicera; E – Leg II; F – Leg III.

FIGURE 2: Ameroseius sternalis n. sp., male: A – Dorsum; B – Venter.