Iphidozercon corticalis Evans

Gwiazdowicz, D. J. & Halliday, R. B., 2008, The Australian species of Iphidozercon (Acari: Ascidae), Zootaxa 1921, pp. 47-68 : 53-57

Iphidozercon corticalis Evans

( Figs 9–16)

Iphidozercon corticalis Evans, 1958: 214 .

Iphidozercon corticalis: Karg, 1965: 285 ; Bregetova, 1977: 207; Walter & Lindquist, 1995: 430; Karg, 1996: 166; Halliday et al., 1998: 24; Sklyar, 2003: 61; Gwiazdowicz, 2003: 153; 2005: 463.

Leioseius (Arctoseius) elegans Bernhard, 1963: 119 . Synonymy by Halliday et al. (1998).

Leioseius elegans: Karg, 1965: 285 .

Leioseius (Arctoseius) elegan s: Bregetova, 1977: 207.

Iphidozercon variolatus Ishikawa, 1969: 121 . Synonymy by Halliday et al. (1998).

Iphidozercon variolatus: Karg, 1996: 165 .

Material examined. Australia, Victoria. 14 females, 6 males, Mount Eliza , 15 August 1991, in compost, D. E. Walter coll. ; 10 larvae, 2 nymphs, 1 female, from laboratory culture derived from Mount Eliza females (in ANIC) .

Redescription. Female. Dorsal idiosoma. Dorsal shield oval, length 380 µm, width 190 µm ( Fig. 9); anterior half with distinct colliculate ornamentation; all setae fine, smooth and pointed, uniform in length, 15 µm; j1 inserted ventrally.

Ventral idiosoma ( Fig. 10). Tritosternum with trapezoidal base and finely pilose laciniae, length of base 30 µm, laciniae 35 µm. Sternal shield rectangular, 90 x 50 µm; setae st1-st3 smooth and pointed, length 15 µm. Metasternal setae st4 length 15 µm. Genital shield small and narrow, length 70 µm, rounded posteriorly. Genital setae st5 15 µm long. Anal shield obovate, length 60 µm, width 60 µm. Para-anal setae 20 µm long, post- anal seta 25 µm, cribrum distinct. Stigmata located at level of coxae IV, peritremes extending anterior to coxae I, projecting well beyond stigmata posteriorly. Opisthogastric skin posterior to coxae IV with a pair of oval metapodal shields, several pairs of very small platelets bearing pores, and ca. 11 pairs of opisthogastric setae, each approx. 25 µm long.

Gnathosoma . Hypostome with robust horn-like corniculi and four pairs of setae ( Fig. 11). Anterior seta h1 longest, 35 µm, palp coxal seta and internal hypostomal h3 setae shorter, 30 µm, external seta h2 shortest, 15 µm. Seven transverse rows of hypostomal denticles present, number of denticles per row (anterior to posterior) 11, 11, 11, 14, 14, 16, 13. Chelicera typical for genus, fixed digit with six teeth, movable digit with two teeth ( Fig. 12), other details of chelicera not visible in available specimens. Tectum with three prongs of equal

length, central prong ending in several denticles, lateral prongs with denticulate outer margins ( Fig. 13). Palp tarsal claw with two unequal tines ( Fig. 15).

Legs. Lengths I 310 µm, II 270 µm, III 250, IV 300µm. Tarsus II to IV each with dorsoproximal setae ad 2 and pd 2 short and straight ( Fig. 14). Setation of genua I-II-III-IV: 12-10-7-7; tibiae I-II-III-IV: 12-9-7-7 ( Fig. 16).

Notes. Iphidozercon corticalis was described from Great Britain ( Evans 1958) and has been collected in Europe, the former USSR, and Japan. It was recorded from Australia by Walter & Lindquist (1995) and Halliday et al. (1998). It is similar to I. poststigmatus , which was described by Gwiazdowicz (2003) from Europe. Both species have a long section of the peritreme behind the stigma ( Ishikawa 1969; Gwiazdowicz 2003). However, the sculpture on the dorsal shield of I. poststigmatus is punctate to areolate and covers the entire shield, while in I. corticalis the sculpture is colliculate and covers only the anterior half of the shield. The anal shield of I. poststigmatus is wider than long, while in I. corticalis the anal shield is considerably elongate and markedly longer than wide.

Halliday et al. (1998) considered I. californicus to be a synonym of I. corticalis . However, we here distinguish between these two species on the basis of the length of the setae on the posterior dorsal shield. In I. californicus setae Z4 and Z5 are more than double the length of J1-J5, while in I. corticalis these setae are all uniform in length ( Fig. 9). This observation is based on the published description and illustrations of I. californicus and study of the type specimens of I. corticalis .

The available collection of I. corticalis includes laboratory-reared immatures. On the dorsal idiosoma of the protonymph, a seta is located at a longitudinal level between Z1 and Z2, and laterad Z1 and Z2. We interpret this seta as S2, following Lindquist & Evans (1965, their Fig. 6), since S1 is not present in the protonymph of Ascidae . If S2 is present in the protonymph, it must also be present in the deutonymph and adult. We therefore consider the anteriormost seta in the S series in Iphidozercon to be S2, and have labelled it so in Fig. 1 and Fig. 25.