Thinoseius papillatus, Halliday, 2010

Halliday, R. B., 2010, Revision of the Australian Eviphididae (Acari: Mesostigmata) 2596, Zootaxa 2596 (1), pp. 1-60 : 46-48

Thinoseius papillatus sp. nov.

( Figs 88–94 , 100, 101 )

Material examined. Holotype. Female, South Australia, Cape Jaffa , 36°56'S 139°40'E, 26 March 2008, R. B. Halliday coll., seaweed on beach (in ANIC) . Paratypes. South Australia. 2 females, same data as holotype ; 3 females, Robe, southern end of Long Beach, 37°46'48"S 139°46'48"E, 26 March 2008, R. B. Halliday coll., seaweed on beach. (all in ANIC) .

Description. Female. Dorsal idiosoma ( Fig. 88 ). Dorsal shield length 596–655 µm, width 370–420 µm (n=6), not completely covering dorsal idiosoma, shield surrounded by a wide strip of papillate skin posterolaterally and posteriorly; surface of shield with distinct polygonal ornamentation throughout, with 13 pairs of setae and ca. ten pairs of pores. Setae on shield uniform in length, ca. 25–30 µm, most curved and directed anteriorly. Other dorsal idiosomal setae inserted in papillate skin outside shield: j 1 30 µm, j 2 and z 1 minute, others gradually increasing in length posteriorly from s 1 (15 µm) to S 4 (30 µm).

Ventral idiosoma ( Fig. 89 ). Tritosternum with bell-shaped base and delicate finely pilose laciniae. Sternal shield reduced to a heavily sclerotised irregularly-shaped transverse ridge bearing setae st 1 and one pair of lyrifissures. Setae st 2, st 3, st 4, second pair of sternal pores, and metasternal pores, inserted in soft skin between coxae II and III. Epigynal shield semi-circular, surface rugose, with one pair of short pointed epigynal setae. Endopodal plates I–II large, irregularly-shaped, free; endopodal plates II–III and III–IV fused to form a large sclerite, its postero-medial edges partly overlain by epigynal shield. Anal shield trapezoidal, wider than long, surface rugose, post-anal and para-anal setae equal in length. Anal shield surrounded by a large area of secondary sclerotisation, its anterior margin abutting posterior margins of coxae IV and epigynal shield ( Fig. 100 ). This sclerotised area strongly ornamented in a mosaic pattern, cells separated by prominent ridges, outer edges indistinct and irregular, grading into striate-papillate postero-ventral skin ( Fig. 101 ), ventri-anal sclerotised area with six pairs of setae, the posterior four pairs heavier than the anterior two pairs. Peritrematal shields narrow, extending from near base of setae z 1 to posterior margin of coxae IV, with short irregularly-shaped post-stigmatal extension and two pairs of post-stigmatal pores. Exopodal plates between coxae I–II large, triangular; II–III smaller, irregular; IV narrow and elongate, embracing coxa IV, antiaxial end extending to mid-level of coxa III; para-axial end sometimes fused with posterior end of endopodal plate IV; metapodal plates completely merged into ventri-anal area of sclerotisation.

Gnathosoma . Rostral setae h 1 65 µm, external setae h 2 shorter, 60 µm, inserted postero-lateral to h 3, internal seta h 3 45 µm, palp coxal seta 30 µm, all fine and needle-like ( Fig. 90 ). Deutosternal groove with irregular margins and five rows of denticles, ca. eight denticles per row, and a smooth anterior line; corniculi robust, slightly curved inward; internal malae with long conspicuous fringes. Seta av on palp trochanter thick, pv finer, twice as long as av, seta al on palp genu and al on palp tibia short, thick, spine-like, tarsus without long sensory setae, palp tarsal claw with two subequal spatulate tines. Epistome with ca. 12 long fine anterior points, central point longest, some points distally subdivided to varying degrees ( Fig. 91 ). Cheliceral digits long and slender, fixed digit with two blunt distal teeth and a low medial ridge, pilus dentilis robust, dorsal seta long and thick ( Fig. 92 ); movable digit with two triangular teeth, arthrodial membrane a rounded flap.

Legs. Chaetotaxy: Leg I. Coxa 0 0/1 0/1 0, trochanter 1 0/1 0/2 1, femur 2 3/1 2/2 2, genu 1 3/2 2/1 2, tibia 1 3/2 2/1 2. Leg II. Coxa 0 0/1 0/1 0, trochanter 1 0/1 0/2 1, femur 1 3/1 2/2 1, genu 1 3/1 2/1 2, tibia 1 2/1 2/1 2, tarsus 3 3/2 3/2 3 + mv, md. Leg III. Coxa 0 0/1 0/1 0, trochanter 1 0/1 0/2 1, femur 1 2/1 1/1 1, genu 1 2/1 2/0 1, tibia 1 1/1 2/1 1, tarsus 3 3/2 3/2 3 + mv, md. Leg IV. Coxa 0 0/0 0/1 0, trochanter 1 0/1 0/2 1, femur 1 2/ 1 1/0 1, genu 1 2/1 2/0 1, tibia 1 1/1 2/1 1, tarsus 3 3/2 3/2 3 + mv, md. All leg setae smooth and pointed, most dorsal setae thickened, ventral and lateral setae fine and needle-like. Tarsi I–IV each with a pair of claws and a strongly developed pulvillus, lateral and median lobes of pulvillus pointed, subequal in length, projecting beyond claws; claws on tarsi I smaller than those on tarsi II–IV; paradactyli on tarsi II–IV very long and pointed, projecting well beyond claws ( Fig. 93 ). Coxae I with two pairs of conspicuous coxal glands ( Fig. 89 ).

Genital structures. Insemination ducts opening on posterior margin of coxae III. Sacculus an irregular, dark coloured mass behind coxae IV (visible in one specimen), ducts entering sacculus via a pair of circular openings ( Fig. 94 ). Some specimens contain a single large egg, 315 x 235 µm.

Etymology. The name papillatus refers to the heavily papillate opisthogastric integument of this species.

Notes. The female of T. papillatus is distinctive in having a heavily sclerotised and strongly ornamented area of skin surrounding the anal shield, resembling a ventri-anal shield, with six pairs of setae in addition to the para-anal and post-anal setae. The only other previously described species with this character state is T. ramsayi Evans from New Zealand (but see T. peltatus below). These two species are easily separated by the appearance of the opisthogastric skin. The skin surrounding the ventri-anal shield and posterior half of the dorsal shield in T. ramsayi is soft, unsclerotised, and finely striated, while that of T. papillatus is heavily sclerotised, with strong papillate ornamentation.

Thinoseius papillatus is unusual in having only seven setae on genu III (pv absent). This character state has also been reported in the Japanese species T. sawadai Takaku 2000 and T. setifer Takaku 2000 . Unfortunately the females of both of these Japanese species are unknown, so it is difficult to compare them with T. papillatus (see Discussion).

Figures

FIGURES 88–94. Thinoseius papillatus, female. 88, dorsal idiosoma; 89, ventral idiosoma; 90, hypostome; 91, epistome, three different specimens; 92, chelicera; 93, pre-tarsus III; 94, insemination ducts and sacculus foeminus. Scale bar = 100 µm for 88, 89; 50 µm for 90, 91, 92; 25 µm for 93, 94.

FIGURES 100–103. Thinoseius spp., females. 100, T. papillatus, anal shield and surrounding opisthogaster; 101, T. papillatus, postero-dorsal opisthosomal skin; 102, T. peltatus, anal shield and surrounding opisthogaster; 103, T. peltatus, postero-dorsal opisthosomal skin. Scale bar = 100 µm for 100, 102; 50 µm for 101, 103.