Scolotydaeus alexanderi Khaustov 2017, comb. nov.
Creators: name: Khaustov, Alexander A.
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Trombidiformes
Paratydeidae
Scolotydaeus
Scolotydaeus alexanderi

description: Scolotydaeus alexanderi (Baker, 1949) comb. nov.
(Figs. 1–4, 12 A)
Paratydeus alexanderi Baker, 1949, p. 120, figs. 1 – 8.
Redescription. DEUTONYMPH (holotype, Figs. 1–4, 12 A). The holotype is in bad condition (Fig. 12 A) with folded legs and several large cuticular folds on idiosoma. Thus, cupules and some setae on legs are not visible. Length of idiosoma 355, width 115. Gnathosoma (Fig. 2 A). Palptarsus with three eupathidia (ul’, ul”, sul). Subcapitular setae m and n subequal. Idiosomal dorsum (Fig. 1 A). Dorsal idiosomal setae distinctly long. Setae sci and sce subequal. Two pairs of eyes well developed; posterior eye slightly smaller than anterior. Hysterosoma with weak transverse furrows between setae d-e, e-f, f-h, respectively. Setae ps 1 and ad 1 distinctly blunt-ended; other dorsal setae pointed. Idiosomal venter (Fig. 1 B). Setae 1 c not evident, but anterolateral corners of coxal fields I covered by legs I and make this area difficult to see. Coxal fields III with only two setae (2 c absent). Genital opening with two pairs of genital acetabulae; setae k not evident. Two pairs of genital and aggenital setae, respectively. Setae ps 2 and ad 2 blunt-ended; other ventral setae pointed. Lengths of idiosomal setae: ve 17, sci 53, sce 56, c 1 42, c 2 66, d 35, e 34, f 1 42, f 2 68, h 1 44, h 2 61, ps 1 28, ps 2 23, ps 3 45, ad 1 23, ad 2 22, ad 3 25, 1 a 26, 1 b 21, 1 d 18, 2 a 30, 2 b 31, 3 a 28, 3 b 50, 3 c 29, 4 a 24, ag 1 24, ag 2 20, g 1 22, g 2 22. Legs (Figs. 2 B, C, 3, 4). Leg I (Fig. 2 B, C). Leg setation: Tr 0, Fe 2/5 (d, l’, l”, v’, v”, d 1, bv”), Ge at least 6(1) (d, l’, l”, l’ 1, l” 1, v’, σ), Ti 8(1) (d, l’ξ, l”, v’, v”, k, l’ 1, l” 1, φ), Ta 14(2) (p’ξ, p”ξ, tc’ξ, tc”ξ, ft’ξ, ft”ξ, a’, a”, u’, u”, s, pl”, pv’, pv”, ω 1, ω 2). Both legs I folded in holotype; tibia and tarsus covered by femur and genu. Only six setae found on genu I (normally 7); it is possible that one seta is situated in the fold between genu and tibia and not visible. Leg II (Fig. 3). Leg setation: Tr 1 (v’), Fe 3 (d, l’, bv”), Ge 3(1) (d, l’, l”, σ), Ti 4(1) (d, l’, v’, v”, φ), Ta 7(1) (p’, p”, tc ’, tc”, u’, u”, ε, ω). Setae (u) distinctly bifurcate; setae (p) and tc” blunt-ended. Empodium very small, about four times shorter than tarsal claws. Leg III (Fig. 4 A). Leg setation: Tr 1 (v’), Fe 3 (d, v’, ev’), Ge 2 (l’, v’), Ti 3(1) (d, v’, v”, φ), Ta 6 (p’, p”, tc ’, tc”, u’, u”). Claws and empodium of same shape as on tarsus II. Only seta u” bifurcate; setae (p) blunt-ended. Leg IV (Fig. 4 B). Leg setation: Tr 0, Fe 1/2 (d, v’, ev’), Ge 3 (d, l’, v’), Ti 3 (d, v’, v”), Ta 5 (p’, p”, tc, u’, u”). Only seta u’ bifurcate. LARVA, PROTONYMPH, TRITONYMPH, FEMALE and MALE unknown.
Material examined. Deutonymph holotype, slide No. 1846, USA, Texas, Brownsville, Plant Quarantine Station, on a twig with bananas from Mexico, 12 November 1947, coll. R.A. Alexander.
Remarks. In his original description, Baker (1949) considered that the single available specimen of Paratydeus alexanderi was a female containing an egg. My examination of this specimen revealed that it is in fact a deutonymph. The structure that Baker (1949) considered as an egg are, instead, poorly cleared internal organs; it is surely not an egg. In addition, Baker (1949) considered that the hysterosoma of P. alexanderi was divided into two parts and that the genital acetabulae were absent. In fact, the anterior part of the opisthosoma is folded and covers the posterior part of metapodosomal, hiding the body constriction behind legs IV, which is typical for other known Paratydeidae. Dorsally, the opisthosoma has weak transverse folds between setal rows d-e, e-f and f-h. Two pairs of genital acetabulae are present, but these are very weakly sclerotized and difficult to see.
The present study of the holotype of P. alexanderi revealed that it is almost the same as deutonymphs of the genus Scolotydaeus. The only significant difference is that P. alexanderi lacks seta 2 c on coxal fields II. However, in some deutonymphs of Scolotydaeus uralensis sp. nov., seta 2 c is absent. Thus, this character is subject to intraspecific variation. Based on the presence of eyes, erect solenidia on legs and palptarsus, bifurcate setae (u) on tarsi II–IV, I consider P. alexanderi as a member of the genus Scolotydaeus and the genus Paratydeus as junior synonym of Scolotydaeus.
description: Published as part of Khaustov, Alexander A., 2017, Review of the Paratydeidae (Acari: Prostigmata), with description of three new species, pp. 151-212 in Zootaxa 4303 (2) on pages 154-156, DOI: 10.11646/zootaxa.4303.2.1, http://zenodo.org/record/840717