Tydeus demeyeri Oudemans, 1928

André, Henri M., 2005, In search of the true Tydeus (Acari, Tydeidae), Journal of Natural History 39 (13), pp. 975-1001 : 991-993

Tydeus demeyeri Oudemans

The only illustration of the species (Figure 29 in Thor 1933) is a dorsal view of the gnathosoma. In his original description, Oudemans (1929b, p 478) wrote: ‘‘Seta verticales internae achter het niveau der pseudostigmata verplaatst’’ (‘‘Verticales internae setae displaced behind the level of pseudostigmata’’). This particular position of prodorsal setae vi (p 1 in Baker’s terminology) behind the trichobothridia means that the prodorsum is procurved, which implies that demeyeri belongs neither to Tydeinae , nor to Tydeidae as recently redefined by André and Fain (2000). The presence of at least 10 (probably 12) setae on tarsus I confirms that demeyeri is not a Tydeidae . Due to the bad state of the specimen, it was not possible to get further information on the species.

Tydeus spathulatus Oudemans

( Figures 2C , 3D , 4C, 4B , 5D , 6B , 9 , 10 )

The species was described by Oudemans (1928b, p 380) and synonymized with caudatus by Thor (1933, p 38). Oudemans (1937, p 925) owned that his spathulatus was a junior synonym of Dugès’ caudatus as proposed by Thor. However, no illustration of the species has ever been published. The major feature reported by Oudemans (1928b) is the presence of six spatulate (‘‘langspatelvormig’’) posterior setae.

The three slides in Oudeman’s collection contain different species. The description of this section refers to the type specimens that Oudemans purchased from Berlese and collected from Padova in Italy. Specimens differ from Oudemans’ description in two points. The posterior opisthosomal setae are not spatulate but rather lanceolate. Depending on the orientation, they sometimes seem to be clavate, but never spatulate (see Figure 3D, E ). The number of lanceolate setae amounts to five pairs ( Figure 10A ), and not three as written by Oudemans. Other dorsal opisthosomal setae are serrate .

Leg chaetotaxy in adults

I(8-4-3-3-1), II(6-2-2-2-0), III(5-2-1-1-1), and IV(5-2-1-1-0). Eupathidia on tarsus I: ft 99, (tc) and (p). Solenidiotaxy: 2. Dorsal setae on genua I and II tapered ( Figure 10B ), on genua III and IV blunt ( Figure 10C, D )

Palp and chelicera

Palp and chelicera apparently similar to those of croceus .

Genital chaetotaxy

(0,?-6-4). Compact striation pattern ( Figure 2C ). The species exhibits the typical Tydeus striation pattern defined by Baker (1965) as well as two eyespots on the prodorsum.

Length of the idiosoma (in Mm)

Length is 368¡16 (n 54) in females and 331¡7 (n 53) in males. NS(vi)526, NS(ep)536.

Designation of a lectotype

As explained in the Material and Methods section, the 12 specimens of this species were remounted separately. Therefore, I hereby designate as lectotype the female remounted in the slide with the original label handwritten by Oudemans. The other slides with new labels contain the paralectotypes.

Figures

Figure 2. The two types of genital striation pattern, extended (A, B) and compact (C, D). (A) Tydeus croceus; (B) T. cruciatus; (C) T. spathulatus; (D) T. nieuwkerkeni. Scale bar: 10 Mm.

Figure 3. Striae density on prodorsum in Tydeus croceus (A), T. cruciatus (B), T. nieuwkerkeni (C) and T. spathulatus (D). NS(vi)528, 22, 27 and 26, respectively. Scale bar: 10 Mm.

Figure 4. Striae density on the 3rd intercoxal area in Tydeus spathulatus (A), T. cruciatus (B) and T. spathulatus (C). NS(ep)536, 18, 32, respectively. Scale bar: 10 Mm.

Figure 5. Shape of terminal dorsal setae, serrate (A), smooth (B), spatulate (C), and lanceolate (D, E). (A) Tydeus croceus; (B) T. cruciatus; (C) T. nieuwkerkeni; (D, E) T. spathulatus. Scale bar: 10 Mm.

Figure 6. Outline of the coxal organ in Tydeus croceus (A), T. spathulatus (B), T. nieuwkerkeni (C), and T. cruciatus (D). Depending on the orientation or state of specimens, the outline may be deformed due to perspective (C) or difficult to see (D).

Figure 9. Dorsal view of Tydeus spathulatus. Scale bar: 80 Mm.

Figure 10. Tydeus spathulatus. The five lanceolate terminal dorsal setae (A), dorsal setae of genu I (B) and IV (C), with a detail of the tip of the former (D). Scale bar: 10 Mm.