Genus Tyroborus Oudemans

Tyroborus Oudemans, 1924a: 307; 1924b: 325; Hughes, 1976: 68. Tyrolichus (in part): Zakhvatkin, 1941: 98; Robertson, 1946: 197. Tyrophagus (Tyroborus): Nesbitt, 1945: 176.

Tyrophagus (in part): Hughes, 1961: 46.

Type species: Tyroborus lini Oudemans, 1924, by original designation.

Diagnosis

FEMALE (Fig. 16–20). Palpal supracoxal seta (elcp) apically bi­ or trifurcate; idiosoma saccate, 300–800 long, whitish to semitransparent. Dorsum with 4 pairs of prodorsal setae (vi, ve, sci and sce) and 12 pairs of hysterosomal setae (c1, c2, c p, c3, d1, d2, e1, e2, f2, h1, h2 and h3), all dorsal setae barbed. External vertical setae obvious, situated at anterior lateral margins of prodorsal shield. Internal scapular setae longer than external scapular setae. Grandjean’s organ finger­like, basally with 3–6 teeth. Supracoxal setae scx broadly widened with dense pectinations. Hysterosomal setae c1 and d2 very short, obviously less than distance to setae in next row; d1 close to c1 and overlapping bases of e1. Coxal plates I not reaching to posterior extremity of prosternal apodeme; coxal plate II reduced to an approximately “L”­shaped sclerite formed by remnant of lateral and anteromedian parts. Genital opening present between coxae III and IV, with 2 pairs of genital papillae covered by genital valves and 1 pair of genital setae (g). Genital folds present. Anal opening posteriorad of genital opening, with 6 pairs of setae (ad3, ps3, ad2, ad1, ps2 and ps1). Spermathecal duct narrowing from copulatory opening for a distance, forming a neck and then gradually widening to base of spermathecal sac. Legs light brown. Tarsi I–II stout, about twice as long as basal width. Dorsoapical seta e on tarsi I–II conical. Proral setae on tarsi I–IV present or absent, if present, conical, more slender than unguinal setae. Chaetotaxy of legs (I–IV): coxae 1, 0, 2, 1; trochanters 1, 1, 1, 0; femora 1, 1, 0, 1; genua 2 + 2, 2 + 1, 1 + 1, 0; tibiae 2 + 1, 2 + 1, 1 + 1, 1 + 1; tarsi 7 + 1 dorsoapical spine + 3–5 ventroapical spines + 3 + 1, 6 + 1 dorsoapical spine + 3–5 ventroapical spines + 1, 4 + 1 dorsoapical spine + 3–5 ventroapical spines, 4 + 1 dorsoapical spine + 3–5 ventroapical spines.

MALE (Fig. 21–25). Similar to adult female except: genital opening situated between coxae IV; aedeagus present; with a pair of anal suckers; without adanal setae; tarsus IV having 2 suckers. Complement of setae on legs as in adult female except tarsi IV with 3 + 1 dorsoapical spine + 3–5 ventroapical spines.

Remarks

After a comparative study of Tyroborus species, including T. lini, T. miripes (Athias­ Henriot) comb. nov. and T. ueckermanni sp. nov., and 17 species of Tyrophagus (Fan & Zhang 2006) we found two new distinct characters, palpal supracoxal seta (elcp) (Figs. 3 C, 8B) and coxal plate II (Fig. 4 A), to separate Tyroborus from Tyrophagus. Four other previously known characters are also useful (Table 1). The proral setae p and q on the tarsi used by Hughes (1976) and Fain (1986) are of little value at the generic level because their size varies from species to species.

Species of Tyroborus are similar to Tyrolichus in dorsoapical seta e on tarsi being conical, tarsi I–II being stout and about twice as long as basal width, supracoxal seta scx having numerous projections, but can be distinguished from the latter by having apically bi­ or trifurcated elcp (Figs. 3 C, 8B) and “L” shaped coxal plate II (Fig. 4 A), both c1 and d2 being very small (Fig. 1 A), and at least one pair of setae surrounding anus in female being short (Fig. 24 B).

Tyroborus houstoni Fain, 1986 is closer to Tyrolichus casei Oudemans, 1910 rather than to species of Tyroborus. Although sci in the larva are shorter than sce, as in Tyroborus lini, this species is not considered a species of Tyroborus because its setae c1, d1, d2, ad1–3 and ps1–3 are relatively long, coxal plate II is not reduced to an “L”­shaped sclerite. Therefore, it is not considered a species of Tyroborus here. Further study is needed to clarify its taxonomic placement.

1. Proral setae on tarsi I–IV prominent (Figs. 8 F, 10A–D); ' longer or as long as " on genu I (Fig. 10 A)........................................................................................................... 2

­ Proral setae on tarsi I–IV absent or vestigial (Figs. 4 C, E, 5A–D); ' obviously shorter than " on genu I (Fig. 5 A); CHINA, CUBA, EGYPT, ENGLAND, INDIA, MEXICO, NETHERLANDS, NEW ZEALAND, SPAIN, TURKEY .......... T. lini Oudemans, 1924

2. Supracoxal seta scx with 32–34 pectinations in male (Fig. 8 D) and 38–46 in female (Fig. 13 C); 1 on tarsus I slightly widened at apex in male (Figs. 9 C); ALGERIA .......

.................................................................................... T. miripes (Athias­Henriot, 1961) ­ Supracoxal seta scx with 16–22 pectinations in male (Fig. 18C) and 16–24 in female (Fig.23 D); 1 on tarsus I obviously widened at apex in male(Fig.19 C); SOUTH AFRICA ................................................................................................... T. ueckermanni sp. nov.