Two new species of the genus Cheiroseius Berlese, 1916 (Ascidae: Mesostigmata) from the Indian Thar Desert
Author
Bhattacharyya, Asit K.
Author
Bhattacharyya, Sisir K.
text
Zootaxa
2004
2004-01-12
403
1
1
11
https://biotaxa.org/Zootaxa/article/view/zootaxa.403.1.1
journal article
4909
10.11646/zootaxa.403.1.1
35b75c67-816f-44fa-9aa8-db362300cd3f
11755334
5027758
CCE71D12-DDB5-44E0-82EC-D8F7AAC0B305
Cheiroseius rajasthanicus
sp. nov.
(
Figs. 9–20
)
Diagnosis
: Dorsal shield with 36 pairs of setae; nine pairs of dorsal setae on tubercles; setae J5 serrated; ventrianal shield broadly triangular, with 9 setae; seven rows of deutosternal denticles, each row with 7–16 denticles; sternitigenital shield in male with four pairs of setae.
FIGURE 9–10:
Cheiroseius rajasthanicus
sp. nov.
, female. 9. Dorsum, 10. Venter. Scale bar: 50µ.
Female
: Dorsal shield (
341µ
long,
157µ
wide) heavily sclerotized, with reticulated ornamentation and 36 pairs of setae; setae j1–j6, z1–z6, s1–s6 and r2–r4 placed on anterior region of the shield; setae r5 occur on the lateral interscutal membrane; posterior region of the dorsal shield complete with 15 pairs of setae; setae R1–R7 occur on the lateral interscutal membrane posterioly; nine pairs of setae borne on raised tubercles; excepting serrated J5 setae (
7µ
), all setae simple, thornlike, abruptly tapering at tips; setae J1–J4
20µ
long, Z5 and S5 are
22µ
and
31µ
long respectively (
Fig. 9
).
Tritosternum long, with moderately pilose lacinae. Sternal shield (
55µ
long along midline,
98µ
wide between two anterolateral corners) finely granulated, slightly concave medially; semicircular structures present at level of first pair of sternal setae; setae st1–st2 and st4 subequal (
7µ
) but shorter than setae st3 (
12µ
); sternal shield convex posteriorly; metasternal shields irregular in shape, with metasternal setae; remnants of endopodal shield present between coxae IIIV. Peritreme moderately wide; poststigmatal prolongation of peritrematal shield encircling coxae IV, divided into several small platelets. Genital shield with genital setae; ventral membrane posterior to genital shield with two pairs of setae (Jv1 and Zv1) and two pairs of postgenital scutellae. Metapodal shields small, present laterally. Ventrianal shield (
78µ
long,
87µ
wide) roughly triangular in outline, with three pairs (Jv2–Jv3 and Zv2) of setae, excluding a pair of para and a postanal seta; postanal seta (
12µ
) shorter than paraanal setae (
20µ
); anal opening large, placed at the middle of ventrianal shield; setae Jv4 and Jv5 placed on ventral membrane and borne on raised tubercles; lineation of ventral membrane around ventrianal shield depicted in fig. 10.
FIGURE 11–16:
Cheiroseius rajasthanicus
sp. nov.
, female. 11. Gnathosoma, 12. Tectum, 13. Chelicera, 14. Tarsus I, 15. Tarsus II, 16. Leg IV. Scale bar: Figs. 11, 12, 14, 15, 16, 50µ; Fig. 13, 39µ.
External malae relatively short, stout (
Fig. 11
); internal malae shorter than external malae, tips curved, slightly outward, outer margin finely fringed laterally; salivary styli archshaped anteriorly; anterior hypostomatic setae and V2 (situated on palp trochanter) almost subequal (
50µ
–
51µ
) but almost double length of posterior one (
25µ
). Ventrally seven rows of deutosternal denticles present, with 7–16 teeth in each row, fifth row widest; lateral margin of deutosternal groove not clearly discernible, rounded structures present in the distal half of lateral groove. Palp apotele twotined; epistome tripartite, all tips with minute denticulate projection (
Fig. 12
). Chelicerae welldeveloped, movable digit bidentate, fixed digit tridentate, pilus dentilis simple (
Fig. 13
).
All legs provided with welldeveloped ambulacra and paired claws; tarsus I slightly longer (
160µ
) than tibia I (
150µ
); length of legs I–IV are
590µ
,
500µ
,
450µ
and
610µ
respectively; tarsus I distally provided with paired claws, 3pointed lobes and sensory setae (
Fig. 14
); tarsus II as figured (
Fig. 15
); some setae on legs II–IV relatively short, spinelike (
Fig. 16
); leg chaetotaxy normal for the genus.
Male
: Holodorsal shield
284µ
long,
182µ
wide; anterior region of the dorsal shield with 19 pairs of setae; posterior region of the dorsal shield with 14 pairs of setae; setae J5 serrated; in both the
paratypes
, setae J3 unpaired and present on the right aspect only (
Fig. 17
).
FIGURE 17–20:
Cheiroseius rajasthanicus
sp. nov.
, male. 17. Dorsum, 18. Venter, 19. Gnathosoma, 20. Chelicera. Scale bar: Figs. 17, 18, 19, 50µ; Fig. 20, 38µ.
Tritosternum normal for the genus. Sternitigenital shield (
118µ
long,
100µ
wide) lineated, with 4 pairs of setae (
Fig. 18
), setae st4 absent; anal orifice at the anteromedian portion of sternitigenital shield. Ventrianal shield (
118µ
long along midline,
175µ
wide between two anterolateral corners) with four pairs of setae, excluding a pair of para and a postanal setae; exopodal and peritrematal shield fused; peritreme moderately wide, stigmata placed at anterior level of coxae IV.
Tectum as in female. Five rows of deutosternal denticles, with 16–30 denticles in each row (
Fig. 19
). Movable cheliceral digit tridentate, fixed cheliceral digit with several small teeth (
Fig. 20
); spermadactyl process not clearly discernible.
All legs with welldeveloped ambulacra and claws; excluding ambulacra, length of legs I–IV as follows:
510µ
,
320µ
,
320µ
and
390µ
; no sexual dimorphism has been observed.
Types:
Holotype
female,
Jaliwada
,
Jodhpur
,
Rajasthan
; ex. soil beside kitchen drainage;
15 January 2001
.
Paratypes
:
2 females
,
Zoological Survey
of
India
compound,
Jodhpur
,
Rajasthan
; ex. decomposed grass litter collected from semidried drainage system;
2 July 2003
;
A.K. Bhattacharyya
coll.
4 females
,
1 male
,
23 March 2003
, collection details same;
5 females
,
1 male
,
27 March 2003
; collection details same;
1 female
,
4 April 2003
; collection details same.
Distribution
:
INDIA
:
Rajasthan
.
Differential diagnosis
: The new species,
Cheiroseius rajasthanicus
superficially resembles
C. indicus
(
Pramanik and Raychaudhuri, 1977
)
in having similar
type
of dorsal reticulation, shape and reticulation of sternal shield as well as the presence of sclerotized platelets between genital and ventrianal shield. However, the new species differs from
indicus
in the following aspects: nature of dorsal setae, serrated J5 seta, shape of metasternal shield and chelicerae.
Lack of congruence between ventral setation of male and female in ascids and their relatives is unusual rather than unknown.
Evans and Hyatt (1960)
mentioned the absence of setae st4 among adult males of all species of
Platyseius
but not in any male of the three
Cheiroseius
species
described therein. In his personal communication, Lindquist informed us that some unidentified species of
Cheiroseius
in the Canadian National Collection also show the absence of setae st
4 in
male specimens. It is considered that in Dermanyssina setae st1–st5 are the most highly conserved chaetotactic series. Since seta st4 is the last one to be added in the deutonymphal stage, it is likely probable that it will be lost later in course of further development
i.e.,
adult. However, in the absence of any detailed further study on different developmental stages, the ontogenetic sequence and mechanism for this
type
of dimorphic suppression will remain uncertain.
Etymology
: The species has been named after the name of the state
i.e.,
Rajasthan
to which the typelocality belongs.