Tydeus cruciatus Koch, 1838

André, Henri M., 2005, In search of the true Tydeus (Acari, Tydeidae), Journal of Natural History 39 (13), pp. 975-1001 : 990-991

Tydeus cruciatus Koch

( Figures 2B , 3B , 4B , 5B , 6D )

The species was also listed as an ‘‘ancient species’’ not identifiable by Kaźmierski (1998). The single illustration of the species was given by Koch (1838). Although they both provided further description of the species, neither Oudemans (1929b), nor Thor (1931, 1933) published additional figures.

Leg chaetotaxy

I(8-4-3-3-1), II(6-2-2-3-0), III(5-2-1-2-1), and IV(5-2-1-1-0). Eupathidia on tarsus I: ft 99, (tc) and (p). Solenidiotaxy: 2.

Genital chaetotaxy

(0,?-6-4). Extended striation pattern ( Figure 2B ). Palp and chelicera apparently similar to those of croceus .

The single female in Oudemans’ collection exhibits the typical Tydeus striation pattern defined by Baker (1965). Striation unique in having circular striae around (vi) similar to those usually observed around the trichobothridia ( Figure 3B ). Dorsal setae smooth ( Figure 5B ). The species is probably small as the idiosoma length was only 235 M m, but this measure is only indicative due to the state of the specimen. The total length published by Oudemans (1929b, p 477) was 247 M m. Koch (1838) had already indicated that the species was exceedingly small (‘‘ungemein klein’’). NS(vi)522, NS(ep)519.

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).