﻿Remarks on the genus Phymatodiscus Berlese, 1917, with the description of Phymatodiscidae fam. nov. and Bardizoneotvosi gen. nov., sp. nov. from Indonesia (Acari, Mesostigmata)

﻿Abstract Phymatodiscidaefam. nov. is diagnosed, with Phymatodiscus as the type genus. A new genus, Bardizongen. nov., with Bardizoneotvosisp. nov. (from Indonesia) as the type species, is erected to accommodate the Phymatodiscus species with an eye-like dorsal depression. Six Phymatodiscus species are reclassified as Bardizon: B.aokii (Hiramatsu, 1985), comb. nov., B.haradai (Hiramatsu, 1985), comb. nov., B.oculatus (Hirschmann, 1977), comb. nov., B.kuni (Kontschán & Starý, 2011), comb. nov., B.insolitus (Kontschán & Ripka, 2016), comb. nov., and B.malayicus (Kontschán & Starý, 2012), comb. nov. The new species differs from the previously described congeners in the sculptural pattern, the shapes of the dorsal and ventral setae, and the sculptural pattern of the sternal shield of the male and the genital shield of the female. A list of all known phymatodiscid species is presented. Phymatodiscustitanicus (Berlese, 1905) is moved to the genus Bostocktrachys: B.titanicus (Berlese, 1905), comb. nov. (family Trachyuropodidae).


Introduction
The genus Phymatodiscus was erected by Berlese (1917) for Discopoma miranda Berlese, 1905. Decades later, Hirschmann (1977) revised this genus and transferred two previously described species, Discopoma conifera Canestrini, 1897 andTrachyuropoda titanica Berlese, 1905, to this taxon.In parallel to the new combinations, Hirschmann (1977) also described four new species from New Guinea.A couple of years later Hiramatsu (1979) described a new species from Japan and two new species from the island of Borneo, Indonesia (Hiramatsu 1985).After a long hiatus, Kontschán andStarý (2011, 2012) described a new species from Vietnam and another new species from Malaysia, and Kontschán and Ripka (2016)  In recent years numerous contributions have added more than 30 new species to the Uropodina mite fauna of Southeast Asia (e.g.Kontschán andStarý 2011, 2012;Kontschán and Kiss 2015;Kontschán and Ripka 2016;Kontschán 2018Kontschán , 2021;;Kontschán and Ermilov 2023a, 2023b, 2023c), but knowledge of this group is still far from complete.The present paper contributes towards our understanding of a poorly investigated group of Uropodina mites from Southeast Asia and is based on the collections of the Natural History Museum in Geneva, Switzerland.

Materials and methods
The specimens of the new species were cleared in lactic acid for a week and afterwards, investigated on half-covered deep slides with a Leica 1000 microscope.Drawings were made with the aid of a drawing tube on a Leica 1000 microscope.Photographs were taken with Keyence 5000 digital microscope.All specimens are stored in 75% ethanol and deposited in the Natural History Museum in Geneva.All measurements and the scale bars of the figures are given in micrometres (μm).

Type genus. Phymatodiscus
Distribution.All known phymatodiscid species occur in New Guinea, Indonesia, Malaysia, Vietnam, and Singapore.
Remarks.Hirschmann (1979) first introduced a family name, Phymatodiscidae, but it was simply listed and without formal description, diagnosis, or designation of a type genus.Following Halliday's (2016) suggestion about Hirschmann's family name, a nomen nudum, we maintain the original name but formally establish it here as a new family.Phymatodiscidae currently includes two genera.
Diagnosis.Phymatodiscid species lacking a pair of eye-like dorsal depressions.Margins of idiosoma with or without many prolongations.

List of the known species
Remarks.One species, Phymatodiscus titanicus (Berlese, 1905), is transferred here from the family Phymatodiscidae to the family Trachyuropodidae Berlese, 1917.According to the dorsal characteristics (only these were illustrated by Berlese 1905: fig.13), our opinion is that this species belongs to the genus Bostocktrachys, as B. titanicus (Berlese, 1905) comb.nov., given that Berlese's species has strongly sclerotized idiosoma and a deep transversal furrow on the dorsal shield (Kontschán and Ermilov 2023c).
Occurrence and biology.This species has been found in New Guinea, but its habitat is unknown (Canestrini 1897).
Occurrence and biology.This species was described from leaf litter in Japan (Hiramatsu 1985).
Occurrence and biology.This species has been found in New Guinea, but its habitat is unknown (Hirschmann 1977).
Occurrence and biology.This species has been found in New Guinea, but its habitat is unknown (Hirschmann 1977).
Type species.Bardizon eotvosi sp.nov.Etymology.The name was suggested by the older son of the first author and derives from small chocolates, which are similar in shape to the idiosoma of these mites. Gender.Male.
Occurrence and biology.This species has been described from soil from Borneo (Indonesia) (Hiramatsu 1985).
Occurrence and biology.This species has been described from soil from Borneo (Indonesia) (Hiramatsu 1985).
Occurrence and biology.This species has been found in New Guinea, where its habitat is unknown (Hirschmann 1977).
Occurrence and biology.This species was collected in Vietnam, in a tropical rain forest (Kontschán and Starý 2011).
Occurrence and biology.This species was found in Singapore, where it was collected from soil (Kontschán and Ripka 2016).
Occurrence and biology.This species was collected in Malaysia from leaf litter (Kontschán and Starý 2012).Diagnosis.Dorsal shield bearing smooth setae except two pairs of apically pilose setae near caudal margin.Surface of dorsal shield smooth, but weblike sculptural pattern situated anterior and posterior to eye-like dorsal depressions.Male sternal shield anterior to genital opening, and female genital shield covered by web-like sculptural pattern.

Bardizon eotvosi
Description.Female (n = 2).Length of idiosoma 1570-1610, width at level of coxae IV 1130-1145, colour reddish-brown.Shape of idiosoma pentagonal, its caudal margin curved.setae., smooth setae at level of oval depressions and near lateral margin of dorsal shield; apically pilose setae near posterior margin of dorsal shield.Marginal shield with some rounded platelets bearing short (ca 18-22), smooth setae on laterocaudal area and some reticulated sculptural pattern on marginal shield anterior to platelets.Other setae on marginal shield similar in shape and length to setae situated on platelets.
Ventral idiosoma (Figs 2,4C,D).Four pairs of sternal setae present.All sternal setae smooth, needle-like, and ca 23-28 long.Setae st1 inserted near anterior margin of sternal shield; st2 at level of posterior margin of coxae II; st3 at level of posterior margin of coxae III; st4 at level of posterior margin of coxae IV.Sternal shield smooth, two pairs of field of poroid-like structures between coxae II and III and coxae III and IV.One pair of lyriform fissures visible near st1.About 13-16 pairs of ventral setae short (ca 25-34), smooth, and needle-like.About 10-14 pairs of smooth, ca 41-48 long and needle-like setae placed on small platelets.;these setae on two pairs of strongly sclerotized, slightly elevated ventral grooves posterior to pedofossae IV.Surface of ventral shield ornamented by oval pits posterior to coxae IV; other part of surface smooth.Anal opening oval (30-32 long and 28-30 wide); anal valves smooth, without euanal setae.Adanal (ca 27-29 long) and postanal (ca 38-41 long) setae smooth and needle-like.Two pairs of poroid-like structures and one pair of lyriform fissures situated lateral to anal opening.Anal area slightly elevated from neighbouring regions.
Genital shield scutiform, length 430-440, basal width 300-315, situated between coxae II and IV; surface of genital shield covered by web-like structures.Stigmata situated between coxae II and III.Presitgmatid part of peritremes with two bends; postsigmatid part very short.Pedofossae deep, their surface smooth, with separate furrow for tarsi IV.Some oval pits situated outside margin of pedofossae.Tritosternum with narrow base; its laciniae subdivided into two pilose lateral branch and one smooth central branch (Fig. 3A).
Legs (Fig. 3C-F).Length of legs (from base of coxae to apex of tarsi): I 665-680, II 525-540, III 485-500, IV 505-518.Leg I with ambulacral claws, but shorter than other legs.On all legs majority of setae needle-like, but some setae serrate and several setae pilose on other leg segments.
Ventral idiosoma (Figs 3G,4E).Intercoxal area, with sternal setae and genital shield as in Fig. 3G.Sternal setae smooth and needle-like.Setae st1 (ca 16-18) near anterior margin of sternal shield; st2 (ca 25-26) at level of posterior margin of coxae II; st3 (ca 26-28) at level of posterior margin of coxae III; st4 (ca 30-84) at level of central area of coxae IV; st5 (ca 25-27) near posterior margin of genital shield.Surface of sternal shield with web-like sculptural pattern anterior to genital opening and with oval pits posterior to genital opening.One pair of lyriform fissures and one pair of poroid-like structures near st1, two pairs of field of poroid-like structures between coxae II and III and coxae III and IV.Genital shield rounded (ca 70-73 × 67-69), its surface smooth, without eugenital setae, and situated between coxae IV.
Other characters as in female.Developmental stages.Unknown.(Hiramatsu, 1985), the most important differences being summarized in Table 1.
Dorsal idiosoma(Figs 1, 4A, B).Marginal and dorsal shields fused anteriorly.Central area elevated from neighbouring regions on dorsal shield (Fig.4B).One pair of eye-like depressions on elevated central part; margins of depressions covered by smooth, short (ca 42-45), needle-like setae.Majority of dorsal shield with smooth surface; web-like sculptural pattern situated only anterior and posterior to eye-like dorsal depressions on central area and some longitudinal lines present posterior to eye-like depressions.Dorsal shield bearing 35-38 pairs of smooth (ca 70-124 long) and two pairs of apically pilose (ca 75-80 long)

Figure 3 .
Figure 3. Dorsal view of Bardizon eotvosi sp.nov., holotype, female A ventral view of gnathosoma B ventral view of palp (arrow shows the palp apothele) C leg I in ventral view D leg II in ventrolateral view E leg III in ventrolateral view F leg IV in ventrolateral view G intercoxal area of male paratype.

Figure 4 .
Figure 4. Photos about Bardizon eotvosi sp.nov., holotype, female A dorsal view of idiosoma B dorsolateral view of idiosoma C ventral view of idiosoma D lateroventral view of idiosoma E ventral view of idiosoma of male paratype.

Table 1 .
Most important differences between the species Bardizon aokii and B. eotvosi sp.nov.