Phyllochthonius peniculus, Fuangarworn, Marut, 2010

Fuangarworn, Marut, 2010, Two new species of the oribatid mite genus Phyllochthonius Travé, 1967 (Acari: Oribatida: Phyllochthoniidae) from Thailand, Zootaxa 2521, pp. 26-36 : 30-35

Phyllochthonius peniculus n. sp.

( Fig. 5 )

Adult female. Dimensions (n=1). Body length 250. Body width (at the level of setae cp) 125. Color light brown.

Prodorsum. Triangular in outline, posterior end slightly narrower than anterior margin of notogaster. Integument weakly sclerotized, surface smooth. Rostrum extended, with irregular teeth laterally. Area between interlamellar setae (in) mostly elevated, except concave anteriorly. Rostral setae (ro), lamellar setae (le), and anterior exobothridial setae (exa) broadly plate-like, with foveae; of these ro smallest with pointed process, le largest, their shape depicted in Figs. 5 A and D. Setae in sub-elliptical, basally narrower than the distal part, and covered by micro-barbs ( Fig. 5 B). Setae exa located at normal position but expand dorsally, able to cover bothridium as well as area in front of setae in. Posterior exobothridial setae (exp) spine-like. Bothridia prominent, with barbed, long flagelliform sensilli ( Figs. 5 A & D, ss).

Notogaster. Generally elliptical in dorsal aspect, posterior rounded ( Figs. 5 A & C); moderately arched in lateral aspect ( Fig. 5 D). Integument weakly sclerotized, surface smooth. Two transverse scissures present, located behind setae row c and just in front of setae row e. Sixteen pairs of notogastral setae present; margins of adjacent setae usually meet. Setae c1, c2, c3, cp, d1, d2, e1, f1, and f2 broadly phylliform or plate-like with foveate pattern; of these, c1 elongate, reaching posterior notogastral scissure, f2 basally broad but dramatically tapered at about distal half, e1 originating on tubercles and permanently erect, e2 originating on tubercles, bottlebrush-like—having thickened, sub-cylindrical stalk and ciliated in distal third ( Fig. 5 E), permanently erect and directed posterio-laterally. Setal rows h and ps on venter; h2, h3, and ps1 –ps3 simple and setiform, h1 basally broad but distally narrow and acute.

TABLE 1. Ontogeny of leg setae and solenidia of Phyllochthonius ovatosetosus n. sp. (placement indicates instar of 1st appearance, dash indicates no change, and parentheses indicates a given pair)

Venter ( Fig. 5 C). Except for epimeres, ventral surface soft. Genital and anal valves delimited by folds of integument. Genital valves with seven pairs of setae. Three pairs of genital papillae present. Ovipositor with simple (uncounted) setae. Anal valves with three pairs of anal setae (an), one pair of peranal setae (pa). Three pairs of adanal setae (ad) present. Epimeral setation 3-1-4-3; all setae short and simple.

Gnathosoma. Generally similar to that of P. ovatosetosus n. sp. Subcapitulum with 3 pairs of setae (a, m, h). Rutellum broad distally with 4 teeth; basal tooth absent. Three pairs of adoral setae present, similar to those of P. ovatosetosus n. sp. Palpi five-segmented; setation 0-2-1-2-9; tarsi with baculiform solenidion ω and terminally with forked eupathidium. Chelicerae dentate with two cheliceral setae, cha minute and chb longer, with barbs.

Legs. Leg I–IV bidactyl. Leg setation similar to that of P. ovatosetosus n. sp.

Male and immatures. Unknown.

Material examined. Female holotype (in alcohol, CUMZ-AC2010.39); north entrance of Tharn-lod Cave, 80 km. NW of Kanchanaburi Province, Thailand (14° 39' N, 99° 18' E); ex. forest litter; 3-III-2008; leg. M. Fuangarworn (Field No. MF 2008-15). No other specimens known. Holotype deposited in the Acari collection at Chulalongkorn University Museum of Natural History, Bangkok. Thailand.

Distribution. Known only from its type locality — Kanchanaburi Province, Western Thailand.

Etymology. The new species is named after the peculiar form of notogastral setae e2, which are bottlebrush-like ( peniculus: Latin , brush).

Remarks. Phyllochthonius peniculus n. sp. has a set of characters that corresponds to the genus Phyllochthonius as redefined below. It exhibits a degree of setal expansion similar to that of P. aoutii, Travé, 1967 . However, these species can be distinguished easily by the shape of setae e2, which are bottlebrush-like in P. peniculus n. sp. but plate-like in P. aoutii . In addition, the new species possesses shorter interlamellar setae, seven pairs of genital setae, and tarsi III lacking solenidia. In P. aoutii , the interlamellar setae are longer than the distance between their bases, eight pairs of genital setae are present, and tarsi III bear a solenidion.

Figures

FIGURE 5. Phyllochthonius peniculus n. sp., female. A, dorsal view; B, interlamellar seta; C, ventral view (without legs); D, lateral view; E, seta e 2 with imaginary cross section.