Charletonia rocciai Treat & Flechtmann 1979

Charletonia rocciai Treat & Flechtmann, 1979

Material examined and new records: Charletonia rocciai specimens were obtained from five localities across southeastern and south Brazil (Fig. 15). UFMG AC 1301036, 1301034, 151437 and 151442 on Psocoptera in pau-ferro trees (Libidibia ferrea (Mart. ex Tul.) Queiroz, 2009) on the campus of the Universidade Federal de Lavras, Lavras, Minas Gerais State (21°13’36.1” S, 44°58’50.5” W), in July 2013 and September 2015. In this same locality a few more specimens were collected in July 2013: one female (UFMG AC 1300421) found on leaf litter and four larvae (UFMG AC 1300612, 1300613, 1301037 and 1301038) found on Psocoptera and reared to deutonymph. One deutonymph (UFMG AC 171474) from a cave in an iron ore terrain (19°13’16.7” S, 43°23’39.1” W) 16–26 January 2017. One larva (UFMG AC 1400806), Atuba Park, Paraná state (25°22’54.1” S, 49°12’11.9” W), 12 February 2013 parasitizing Auchmerina limbatipennis Enderlein, 1918 (Psyllidae), host determined by D. Burckhardt and D. L. Queiroz but subsequently lost. One larva on unidentified insect, Parque Estadual Serra do Rola Moça, near to Belo Horizonte, Minas Gerais State (20°04’00.8” S, 44°00’08.6” W). One male (UFMG AC 1301003), Serra do Japi, Jundiaí municipality, São Paulo State (23°14’30.8”S 46°56’04.9”W). One larva, one deutonymph deposited at OSAL (OSAL 114444 and 114509, respectively) studied by Rosa & Flechtmann (1980), and the holotype deposited at USPB (no specimen identification number).

Diagnosis

Larvae: Measurements summarized in Table II. No significant morphological differences were observed between our specimens and the holotype. However, we could notice a few details unreported in the original description (Treat & Flechtmann 1979). Larva has one distal microseta present on genu II (Fig. 16), visible on only one side of the holotype and missing in the original description. Additionally, our specimens have fnTi: 18-19-19 (vs. 18-19- 18 in the original description and 18-19-19 observable on one side of the holotype). Complete illustrations of newly collected larvae in Supplementary Material (Figs. S1–S 3), in addition to new images of the type material.

Deutonymph (Fig. 17A): Measurements summarized in Table III. Color in life red. Crista without a surrounding sclerite; two pairs of filiform sensillary setae with faint distal setules; 2–4, robust, setae with distinct setules (100–143) at anterior border of crista, anteriorly to Asens (Fig. 17B). Dorsum with two types of setae, long (pDS I) and short (pDS II), often with setules. pDS I setae with blunt tips, pDS II with attenuate tips (Fig. 18G). Ventral setae (43–57) numerous, with barbs and a few longer setae (104–111) (Fig. 18H).

Mouth cone bearing a few long setae distally in dorsal view and many setae in ventral view; hypostomal lip fimbriate. Cheliceral blades strong, straight, stylet-like. Palpi robust, numerous palpal scobalae with setules. Palp tibia with one long seta (Fig. 18F: S). Palp tibial claw strong, curved, pointed (Fig. 18F). Palp tarsus ovoid, with numerous setulose setae, and distally, many short setulose setae, brush like (Figs. 17D, E; 18F).

Relative leg lengths: IV>I> III> II. Leg scobalae numerous, pointed, tapering, with slight indications of setules. Tarsi I with three distinct long setae: S1 and S 2 in the proximal half and S 3 in the distal half (Fig. 17C). Similar setae figured in drawings of Charletonia oudemansi (Southcott, 1966) and in Charletonia cardinalis (Koch, 1837). Tarsal claws strong, smooth, falciform.

Vestigiala distribution on legs:

Leg I: Cx—1κ; Ge—1κ (Fig. 18A); Ti—3κ (Fig. 18B); Ta—1κ 1ɛ (Fig. 18C).

Leg II: Ge—1κ (Fig. 18D); Ti—1κ (Fig. 18E).

Female (Fig. 19 A–H): Measurements in Table IV. Idiosoma oval, crista without scutum; two pairs of sensilla; eight, robust, straight scutalae placed anteriad, without distinct setules (116–194, Fig. 19F). Eyes positioned posterior to middle of crista (Fig. 19G). Numerous dorsal setae (DS), divided into two types: short, thin setae (pDS II, 24–56), and robust, blade-like (pDS I, 57–130); both types with indistinct setules and rounded tips (Fig. 19G). Ventral setae (30–56) with numerous but weak setules, few longer setae (92–130). Genital pore bearing two similar pairs of genital acetabula (G.ac.) kidney-shaped (Fig. 19B). Female anal plates lightly sclerotized, with six setae on each valve (Fig. 19B). The legs were broken and mixed in the slide during the extraction of the DNA, however it was possible to identify the tibia I and tarsus I by the vestigiala distribution (Fig. 19H). Gnathosoma and palp similar to the deutonymph (see Fig. 19E, F).

Male (Figs. 20, 21): Measurements in Table V. Idiosoma oval (Fig. 20A). Crista without a scutum, with two pairs of sensillar setae with almost imperceptible setules distally. Crista bearing eight, robust, straight setae with weak setules (116–194), on anterior sensillar area (Fig. 20C). Similar to the female regarding most characters, including idiosomal setae (Fig. 20C). The male and female examined differ in the dorsal ornamentation of palp femur and genu, male with larger pits (black arrowhead on Fig. 20D), and only faint dots in the female (Fig. 19 C–D). Male genital pore rounded, 441 long and 272 wide. Internally, operculum composed of two, anteriorly articulated, longitudinal sclerites of the ejaculatory complex with numerous eugenital setae over protuberances. Ejaculatory complex skeleton visible in light microscopy, distance between tips of proximal arms 331, between tips distal arms 385 (Fig. 20F). Male anal plates lightly sclerotized, with nine setae on each valve (Fig. 20F). Anal plates with nine setae (vs. six setae in females).

Leg I> IV> III> II. Leg setae numerous, pointed, tapering, with slight indications of setules. Tarsus II more squarish (width/length= 0.51) than Ta I, III and IV (width/length= 0.42, 0.40 and 0.37, respectively) (Fig. 20A and B). Tarsal claws strong, smooth, falciform.

Vestigiala distribution on legs:

Leg I: Cx—1κ; Ge—1κ (Fig. 21C); Ti—3κ (Fig. 21A and B).

Leg II: Ge—1κ; (Fig. 21E); Ti—1κ (Fig. 21D).

Rearing and behavior: The collected psocopteran hosts (Fig. 14 A–D) were placed in rearing containers. In the first attempt, 38 insects, including six infected by a total of 15 mites (1–5 mites per insect) were kept for 10 days. On this occasion, only two mites developed to the deutonymphal instar.

In the second attempt, 26 Psocoptera were collected, carrying 12 mites. On this occasion, insects were kept alive for 18 days and six mites reached the deutonymphal instar. Engorged larvae detached from their hosts, seeking shelter in cracks in the substrate and then remained motionless, becoming calyptostases, and remained so for at least two days. After emerging, deutonymphs were preserved in 100% ethanol.

Larvae switched hosts during the experiment. Three of the infested Psocoptera were marked with a white water-based ink (gouache paint) when bearing a single mite each and observed for five days. In this time, the number of mites per marked host ranged from 1–4 mites in two, 0–3 in the third host specimen. The maximum number of mites per psocopteran either in the field or in culture, was five mites per host. The exact phase of parasitism (state of engorgement) in which the shifts happened couldn’t be estimated since at the time that the specimens were collected, they were already attached to their host and the level of engorgement wasn’t recorded. This disallowed a test of the hypothesis by Wohltmann (2000) that host switches are restricted to the earliest phases of attachment.