Platyacarus Kudon, 1982

Mironov, Sergey V., Literak, Ivan, Sychra, Oldrich & Capek, Miroslav, 2017, Feather mites of the subfamily Proctophyllodinae (Acari: Proctophyllodidae) from passerines (Aves: Passeriformes) in Costa Rica, Zootaxa 4297 (1), pp. 1-105 : 6-7

Genus Platyacarus Kudon, 1982

Type species: Platyacarus oligolaccius Kudon, 1982 , by original designation.

Diagnosis. BOTH SEXES. Moderately elongated proctophyllodines. Prodorsal shield covering nearly all prodorsum, entire or split into two pieces by transverse poorly sclerotized band, with antero-lateral extensions.

Vertical setae vi rudimentary, represented by alveoli or absent. Scapular setae si and se arranged in transverse line, situated on prodorsal shield or on a transverse band of soft tegument. Humeral shields well developed dorsally, encompassing bases of setae cp, setae c2 on these shields. Subhumeral setae c3 lanceolate or spiculiform. Hysterosomal setae c1, f2 present or absent. Solenidion σ1 of genu I shorter than solenidion ω3 of tarsus I. Tarsi I, II with 4 ventral setae (la, ra, wa, and s), seta wa close to setae la and ra on these tarsi. Segments of legs I and II without processes or other modifications.

MALE. Hysteronotal shield covering almost all hysterosoma. Opisthosoma attenuate posteriorly. Opisthosomal lobes short, rounded or truncate, separated by usually small terminal cleft of semiovate or semicircular form. Posterior margin of lobes with small terminal lamellae variable in form (tongue-shaped, triangular, spiculiform or spatuliform). Supranal concavity present, narrowly ovate or teardrop-shaped. Setae h3 long, whip-shaped, comparable in length to macrosetae h2. Setae h1 distinctly anterior to level of setae ps2. Epimerites I convergent, fused into a Y or V. Coxal fields I–IV open, without extensive sclerotized areas. Genital apparatus usually at level of trochanters IV; genital arch of moderate size. Aedeagus in genital sheath much longer than genital arch, but in most species not extending beyond lobar apices. Adanal shields present, represented by 1 or 2 pairs usually of ovate form, situated antero-lateral to adanal suckers and setae ps3. Genital papillae situated at level of genital arch apex, on soft tegument or on small ovate plates. Pregenital apodeme absent; paragenital apodemes present or absent; if present situated lateral to genital apparatus. Adanal apodemes absent (present in Platyacarus caulifer sp. n.). Opisthoventral shields not developed. Adanal suckers cylindrical or cup-shaped, corolla dentate or edentate. Legs III and IV subequal in size. Tarsus IV without apical claw-like processes, modified tarsal setae d and e button-like.

FEMALE. Lobar region of opisthosoma clearly separated from remaining part of hysterosoma, opisthosomal lobes well developed, with terminal appendages. Anterior hysteronotal and lobar shields separated by narrow band of striated tegument (not split in Platyacarus trigonicus Kudon, 1982 ). Lobar shield entire. Supranal concavity absent. Macrosetae h2 thickened basally, with filiform apex. Epimerites I with posterior tips convergent, connected by very thin commissure or free. Epigynum large semicircular, with tips acute or bidentate. Translobar apodemes present, fused to each other anterior to terminal cleft. Copulatory opening subterminal, situated between anal opening and anterior margin of fused translobar apodemes. Legs III and IV subequal in size; segments without modifications. Solenidion φ of tibia IV usually shorter than on tibia III.

Hosts: Furnariidae .

Remarks. (1) The genus was established by Kudon (1982a, 1982b, 1982c, 1982d, 1982e), who in a series of papers described 12 species and gave an analysis of their distribution among woodcreepers ( Furnariidae : Dendrocolaptinae ), an endemic group of suboscines restricted to tropics of the New World. Based on the morphological features of the male opisthosoma, this author arranged all described species into four species groups: acaenophyllicus , epacrophyllicus , oligolaccius and psilocoronius . In further investigations, one new species was described and one, Platyacarus minor (Berla, 1959) , was transferred from the genus Proctophyllodes Robin, 1868 ( Hernandes et al. 2007; Hernandes & Valim 2014). The latter study showed that the genus Platyacarus is not restricted to the subfamily Dendrocolaptinae , but is widely distributed among the Furnariidae . At present the genus includes 19 species including five described herein. Two new species groups, caulifer and minor , are established in this paper.

(2) A new key to species provided below is based in part on that by Kudon (1982e), but expanded by new characters for identification of previously known species. Platyacarus brevicolicus Kudon, 1982 originally referred to the epacrophyllicus group does not correspond to the diagnosis of that group and cannot be identified with the key by Kudon (1982e); this species is transferred here to the acaenophyllicus group.

(3) Our study has shown that the genus Platyacarus has four ventral setae on tarsi I and II (la, ra, wa, and s), rather than three (la, ra, and wa) as for all other proctophyllodids ( Atyeo & Braasch 1966; Park & Atyeo 1971a). This morphological feature was not noticed by previous investigators ( Kudon 1982a; Hernandes et al. 2007). A phylogenetic study of proctophyllodids based on molecular data ( Knowles & Klimov 2011) showed that the genus Platyacarus is not the most basal lineage of Proctophyllodidae but is nested in the clade constituting the subfamily Proctophyllodinae . Therefore, two hypotheses can be drawn out to explain the presence of setae s on tarsi I, II in this genus. Their presence is either the result of reversal of setae s, which is more probable, or these setae have been lost independently in the subfamily Pterodectinae and in the branch comprising the remaining proctophyllodine genera.