Austrophthiracarus trapezoides, Fuangarworn, Marut & Lekprayoon, Chariya, 2011

Fuangarworn, Marut & Lekprayoon, Chariya, 2011, New species of oribatid mites in the families Synichotritiidae and Phthiracaridae from Thailand, with a checklist of Thai Euptyctima (Acari: Oribatida: Euphthiracaroidea, Phthiracaroidea), Zootaxa 3106, pp. 24-41 : 31-35

Austrophthiracarus trapezoides sp. nov.

( Figs. 6–8 )

Diagnosis. Prodorsum with distinct lateral carina; sensillus curved and slightly clavate; lamellar seta (le) short, attenuate; interlamella seta (in) long, thickened and covered with minute barbs; rostral seta (ro) barbed, thinner than in; mutual distance of setae: le -le> in -in ≈ ro -ro; one pair exobothridial setae present; median prodorsum with strong elevation, trapezoidal in dorsal view; surface on anterior half of prodorsum foveolate; median field deeply split, not fused to sigillar fields ( Fig. 7 B); notogaster covered with fovea; with fifteen pairs of setae, all long, thickened and barbed in distal half; length of seta c1 about distance of setae c1-d1 insertions; seta c3 located near anterior border of notogaster; subcapitular setae h about as long as their mutual distance; genito-aggenital shield with nine genital setae arranged in two rows; genital setae formula 6(4+2):3; ano-adanal shield with five setae; ad2> ad1> ad3 ≈ an2> an1.

Description. Measurements of holotype (range of paratypes in parentheses): prodorsum 309 (309–442) long, 226 (206–309) wide, and 175 (165–226) high; notogaster 618 (618–875) long, 453 (432–556) wide, and 463 (412 – 618) high. Color: body uniformly dark yellow.

Prodorsum ( Figs. 6 A–D, 7B). Rostrum broadly rounded; lateral carina distinct, originating dorsad of bothridium and running to near lateral margin of prodorsum. Sensillus (ss) 90 long, curved and slightly clavate, covered with short spines ( Fig. 6 E). Lamellar seta (le) short, about 30, attenuate and smooth. Interlamellar seta (in) 185 long, thickened but gradually tapered and covered with minute barbs in distal half. Rostral seta (ro) 95 long, slightly thickened but thinner than in, with minute barbs. Mutual distance of setae: le -le> in -in ≈ ro -ro. Anterior exobothridial seta (exa) minute. Median prodorsum with strong elevation, having Hornbill-like appearance in lateral view, and trapezoid shape in dorsal view; its dorsal side with longitudinal groove along lateral margin ( Figs. 6 B, 6C) while anterior and lateral sides concave and usually filled with dirt ( Figs. 6 A, 7A). Prodorsal integument foveolate restricted to surface between setae le and rostrum; posterodorsal and posterolateral surface smooth or finely granulate. Three to four short carinae present posteromedially to bothridium. Sagittal apodeme short; median field deeply split; sigillar fields normal ( Fig. 7 B).

Notogaster ( Figs. 6 A, 7A). Surface strongly foveolate. Fifteen pairs of setae present, all long, thickened and covered with small spines in distal half; dorsal setae longer than others; seta c1 about distance of c1–d1 insertions; seta c3 located near anterior border of notogaster; vestigial alveoli of setae f1, f2, and lyrifissure ia, im present, their distribution as depicted in Fig. 6 A.

Gnathosoma ( Figs. 7 C–E). Subcapitulum normal ( Fig. 7 C); setae h, m, and a simple with minute barbs; length of setae h about mutual distance of their pair. Adoral seta or1 apparently flat with barbs; or2-3 simple and barbed. Palp ( Fig. 7 D) four segmented, femur and genu fused; palpal setation 0-2-2-7(1). Supracoxal seta simple with barbs. Chelicera ( Fig. 7 E) chelate-dentate with two barbed cheliceral setae (cha, chb).

Ano-genital region ( Figs. 7 A, F–I). Genito-aggenital shields each with nine genital setae arranged in two rows; setae g6-9 thickened, more curved than others and located further from inner margins; setae g1-5 thinner and straight; g1-3 directed anteriorly, g4-5 directed mesially ( Figs. 7 F–G); aggenital seta (ag) present at normal position; field around setae g6-9 slightly protruded in V-shape ( Fig.7 F). Ano-adanal shields protruded, in lateral view; each with five setae of which two (an1, an2) born on elevated inner margin; adanal setae (ad1-3) thicker than anal setae; relative length of setae: ad2> ad1> ad3 ≈ an2> an1.

Legs ( Figs. 8 A–D). All legs monodactyl; claws with small ventral spine. Legs I–IV setation (famulus included, solenidia in parentheses): trochanter, 1-1-2-2; femur, 4-3-2-1; genu, 2(2)-2(1)-1(1)-1; tibia, 5(1)-3(1)-2(1)-2(1); tarsus, 15(3)-12(2)-10-10. Setal homology depicted in Figure 8 . Seta d on tibia IV short and coupled with solenidion.

Distribution. Thailand: Payan Is. and Payu Is. in Similan Archipelago, Pang-Nga Province.

Etymology. The new species is named after its unique structure of the median tubercle on prodorsum, being trapezoidal.

Material examined. Holotype: Adult (in alcohol, CUMN-AC2011.02); Thailand, Payan Is., Similan Archipelago National Park, Pang-Nga Province (8°30'56"N, 97°39'18"E); ex. forest litter; 5-IV-2010; coll. Jirawat Damkaew (Field No. MF 2010-23). Seven paratypes, (CUMN-AC2011.03–09) with same data as holotype. Six paratypes (CUMN-AC2011.10–15) Payu Is., Similan Archipelago National Park, Pang-Nga Province (8°35'20"N, 97°37'59"E); ex. forest litter; 6-IV-2010; coll. M. Fuangarworn (Field No. MF 2010-27). One adult paratype, (CUMN-AC2011.16) with previous data but Field No. MF 2010-28. Holotype and most paratypes deposited in the Acari collection at Chulalongkorn University Museum of Natural History, Bangkok, Thailand. Two paratypes each will be deposited in the Muséum d’Histoire Naturelle, Genève and the Department of Animal Taxonomy, and Ecology, Adam Mickiewicz University, Poland.

Remark. Austrophthiracarus trapezoides sp. nov. is similar to A. pseudotuberculatus Mahunka, 2008 , also described from Thailand, in the presence of a strong median elevation or tubercle on the prodorsum and the protruding inner margin of the ano-adanal shields. We found the specimens identified as A. pseudotuberculatus in the same area of A. trapezoides sp. nov. They, however, show distinct morphological differences and lack of any intermediate forms between the two, leading us to conclude that they are distinct species. The new species can be distinguished from A. pseudotuberculatus by having 1) the trapezoid tubercle on median prodorsum (vs. a pair of robust longitudinal cristae, each with narrow distal end and slightly converged, resulting in “M-shape” appearance); 2) long notogastral setae, c1 reaching insertion of d1 (vs. shorter notogastral setae, c1 not reaching insertion of d1); 3) seta le thickened, thicker than exa (vs. lesser developed, or similar to exa); and 4) seta v’ on leg femur I well developed, about one-third of bv” (vs. minute or short spine-like, about one-fifth of bv”).

Figures

FIGURE 6. Austrophthiracarus trapezoides sp. nov., adult. A) Habitus, lateral view, prodosum covered with dirt; B) prodorsum, dorsal view, dirt removed; C) same, frontal view; D) same, lateral view; E) sensillus, not to scale.

FIGURE 7. Austrophthiracarus trapezoides sp. nov., adult. A) Habitus, ventral view, prodorsum covered with dirt; B) prodorsum, anterior portion, illustrating the field beneath median tubercle; C) subcapitulum, palpi removed; D) palp, antiaxial view; E) chelicera, paraxial view; F – G) genito-aggenital shields, ventral and lateral view, respectively; H – I) ano-adanal shields, ventral and lateral view, respectively.

FIGURE 8. Austrophthiracarus trapezoides sp. nov., adult. A – D) legs I – IV, respectively, antiaxial view.