Adamystis thailandensis, Fuangarworn, Marut & Lekprayoon, Chariya, 2010

Fuangarworn, Marut & Lekprayoon, Chariya, 2010, Adamystis thailandensis sp. nov. (Acari: Prostigmata: Adamystidae), a new species of soil mites from Thailand with a key to world species of Adamystidae, Zootaxa 2649, pp. 61-68 : 62-66

Adamystis thailandensis sp. nov.

( Figs. 1–3 )

Diagnosis. Adults unique among Adamystis in having following combination of character states: subcapitulum with 2 pairs of adoral setae; chelicera with 1 seta; palpal setation 0- 2 -3-10(1); idiosoma with densely striated dorsal shield; presence of lens-like structures on lateral, ventral, and postero-dorsomedial surface of idiosoma.

Female (holotype). Body length (from tip of naso to posterior end of idiosoma) 440 (440–450 in 5 paratypes); body width (greatest width of idiosoma) 295 (250–300).

Gnathosoma. With 4 lips; subcapitulum striate with 2 pairs of adoral setae on lateral lips ( Fig. 1 B). Chelicerae 60 (60–80) long, typical for genus, bearing 1 seta ( Fig. 1 G). Palp 125 (125–125) long; palpal femurogenu with 2 barbed setae; tibia with 3 barbed setae; tarsus with 1 solenidion and 10 setae of which 4 barbed and 6 smooth eupathidia ( Fig. 1 H). Palpal supracoxal setae peg-like. Stigmatic opening situated between cheliceral bases giving rises to short peritremes ( Fig. 1 E).

Idiosoma. Dorsum ( Fig. 1 A) — Integument striate. Dorsal shield present, distinguishable from surrounding integument by dense striations. Propodosoma with 4 pairs of setae (vi, ve, sci, sce), of which vi and sci trichobothria ( Fig. 1 F), all filiform with microbarbs. Naso present, bearing trichobothria vi; surface dorsally reticulate, and ventrally striate ( Figs. 1 C & D). One pair of eyes associated with postocular bodies and lyrifissures present next to sce. Lengths of propodosomal setae: vi 41, ve 36, sci 45, and sce 37. Hysterosoma with 8 setal rows (c, d, e, f, h, ps, ad, and an) with 2, 1, 1, 1, 2, 3, and 4 pairs of setae, respectively; all setae filiform with microbarbs. Lengths of hysterosomal setae: c1 26, c2 33, d1 24, e1 26, f1 28, h1 30, h2 24, ps1 23, ps2 21, ps3 18, ad1 17, ad2 17, ad3 18, an1 18, an2 17, an3 16, and an4 16. Four pairs of lyrifissures (ia, im, ip, ih) present. Setae sce, c1, d1, e1, and lyrifissure ia and im located on dorsal shield. Nine or 10 lens-like structures present in line along lateral margin of idiosoma and additional 7 pairs on posterior dorsomedial surface of hysterosoma, flanked by setal pairs f1, h1 and ps1 (see variations below). Ve n t e r ( Fig. 1 B) — Integument striated, especially densely so on genital and anal valves; sclerotized ventral shields absent. Coxal bases weakly radiate, not well delimited medially; their surface striated. Eight pairs of intercoxal setae present, all of them filiform and apparently smooth, located on finer striation. Genital area with 14 or 15 pairs of genital setae and 4 pairs of aggenital setae, all filiform with microbarbs and flanked by 8 pairs of lens-like structures ( Fig. 1 B). Two pairs of genital papillae (Va and Vp) present, Va larger than Vp; 2 pairs of setae k (k1 and k2) present. Eugenital setae not discernible ( Fig. 2 A).

Legs ( Fig. 3 ). Measurements of holotype (from trochanters to tarsi, pretarsi excluded): Leg I, 320 (320– 350 in 5 paratypes); leg II, 320 (310–320); leg III, 340 (335–350); leg IV 415 (405–435). All femora incompletely fused, remnant of suture present ventrally. Legs I–IV setation (solenidia in brackets): coxae 1-3- 3-3; trochanters 2-2-2-1; basifemora 5-5-4-2; telofemora 6-6-5-4; genua 7(1)-7(1)-5(1)-6; tibiae 14(1)-13(1)- 13(1)-14; tarsi 29(1)-29(1)-26-22. Pretarsi I-IV with 2 bipectinated claws and small claw-like empodium. Supracoxal setae epI peg-like; solenidia rod-like; famuli on tarsi I–II peg-like. Most setae barbed filiform, except for smooth eupathidial setae with blunt tip. Eupathidia present on genua to tarsi of legs I–III, and on tibiae to tarsi of leg IV. Their distribution depicted in Fig. 3 .

Male. Body length 425–450, body width 225–275, leg I 320–335, leg II 310–325, leg III 345–346, leg IV 410–415. Generally similar to female except for presence of internal genitalia, and densely striated surface bearing setae ag1–ag3 ( Fig. 2 B) and flanking genital valves anterolaterally. Genitalia ( Figs. 2 C & D) with 8 pairs of eugenital setae. Idiosoma laterally with 10 pairs of lens-like structures, ventrally with 7 pairs and posterior dorsomedially with 4 pairs.

Tritonymph. Body length 375, body width 250, leg I 260, leg II 250, leg III 275, leg IV 300. Dorsal aspect generally similar to female. Venter with 6 pairs of genital setae and 4 pairs of aggenital setae. Two pairs of genital papillae present. Coxal setation 1-2-3-2 with 7 pairs of intercoxal setae. Idiosoma with 7 pairs of lens-like structures laterally, 6 or 8 pairs ventrally and 4 or 5 pairs posterior dorsomedially. Palpal setation 0- 2-3-8(1).

Deutonymph. Body length 320, body width 215, leg I 225, leg II 215, leg III 235, leg IV 275. Venter with 2, on right, and 3, on left, genital setae; 3 pairs of aggenital setae. Two pairs of genital papillae present. Coxal setation 1-1-2-2, with 5 pairs of intercoxal setae. Idiosoma with 11 pairs of lens-like structures laterally, 6 or 7 pairs ventrally and 4 pairs posterior dorsomedially. Palpal setation 0-2-3-8(1).

Protonymph. Body length 200, body width 110, leg I 175, leg II 170, leg III 180, leg IV 210. Genital setae absent; with 2 pairs of aggenital setae; 1 pair of genital papillae present. Coxal setation 1-1-2-0, with 3 pairs of intercoxal setae. Idiosomal lens-like structures absent laterally and ventrally, but 7 or 8 pairs present on posterior dorsomedial surface of hysterosoma, flanked by setal pairs f1, h1 and ps1. Palpal setation 0-2-3- 8(1). Legs IV tridactyl (empodia IV smooth, slender, claw-like).

Larva and prelarva. Unknown.

Variations. Among examined females, the lens-like structures occur consistently in three groupings: lateral-supracoxal, ventral, and posterior-dorsomedial region of idiosoma. However, there is some variability of the number of these structures within each group. At lateral-supracoxal region, the lens-like structures vary from seven to ten and are usually asymmetrical in number (± one or two) between the two sides of the idiosoma. The most frequent pattern is 8:9. Ventrally, these organs vary from six to eight and also occur asymmetrically (± one or two), but the most common pattern is 8:8. On posterior dorsomedial surface of the idiosoma, however, these structures occur symmetrically in number of five to seven pairs. The most common number is six pairs. Furthermore, the lens-like structures are usually arranged asymmetrically ( Figs. 1 A, B). These patterns of variation, the asymmetry of number and arrangement, are similar to those of Adamystis oculeusis Ueckermann, 1989 .

Type material. Holotype female (CUMZ-AC-2010.57), Thailand: Pang-Nga Province, Thaimuang District, Hard-Thaimuang Khao-Champee National Park, 8°29'38"N, 98°13'39"E, from soil and leaf-litter in a coastal Melaleuca forest, 15 March 2005, coll. M. Fuangarworn and C. Chaisuekul. Five female, two male, one tritonymph, one deutonymph, and one protonymph paratypes (CUMZ-AC-2010.58 – 67) with same data as holotype. One male paratype (CUMZ-AC-2010.68) with same data as holotype except 7 February 2005, coll. E. Mongkolchaichana. Holotype and paratypes are deposited in the Acarology Collection at Chulalongkorn University Museum of Natural History, Bangkok, Thailand. One female and one male paratype will be deposited in the Acarology Collection at the Ohio State University, Columbus, USA.

Etymology. The new species is named after the country of its origin, Thailand.

Remarks. Among previously described species of the genus Adamystis , four species possess the lens-like structures on the idiosoma, varying from one to 20 pairs— A. fonsi Coineau 1974 (one pair), A. buchelis Ueckermann, 1989 (two pairs), A. sarae Hunter and Crossley, 1968 (13–14 pairs) and A. oculeusis Ueckermann, 1989 (17–20 pairs). Adamystis thailandensis sp. nov., with 20–25 pairs, exhibits the largest number of such structures. The function of these organs is still unknown. Adamystis thailandensis sp. nov. is most similar to A. oculeusis from South Africa in having the lens-like structures laterally, posteriordorsomedially (between the setal pair ps1) and ventrally on the idiosoma; one seta on the chelicerae; and eight pairs of the intercoxal setae. The new species can be readily distinguished from A. oculeusis by having the idiosomal shield densely striate (vs. reticulate in A. oculeusis ), setae f1, h1 and h2 located on integument (vs. on dorsal shield), ten setae on the papal tarsi (vs. nine), and the setation of leg telofemora I–IV 6-6 -5-4 (vs. 6 or 7-7-7-7) and that of genua III–IV 5 (1)-6 (vs. 7(1)-7).

The family Adamystidae was subdivided initially by Coineau (1974, 1979) into two subfamilies, Adamystinae with the genus Adamystis , and Saxidrominae with the genus Saxidromus . Later on, Coineau et al. (2006) recognized Saxidromidae (which included to this time also the monobasic genera Bovidromus and Rhinodromus ) as a separate family. Walter et al. (2009), however, did not support this taxonomic decision and considered Saxidromidae as the subfamily of the family Adamystidae . We follow to this classification here.

Figures

FIGURE 1. Adamystis thailandensis sp. nov., female. A, dorsal view; B, ventral view; C, naso, dorsal view; D, naso ventral view; E, peritremes; F, trichobothrium sci; G, chelicera; H, palp.

FIGURE 2. Adamystis thailandensis sp. nov., adults. A, female ovipositor and genital papillae, seen through the integument; B, male genital area; C and D, male genitalia, in dorsal and ventral view, respectively.

FIGURE 3. Adamystis thailandensis sp. nov., female. A, leg I, paraxial view; B, leg II, dorsal view; C, leg III, dorsal view; D, leg IV, antiaxial view.