(Figs. 5–12, 16– 17)
Material examined: Holotype: adult (in alcohol, CJ-01- 98), CHINA: Xizang Autonomous Region: Nyalam County, Zham (27.9°N, 85.9°E), 2670m, 3 Sept., 2001, Jun Chen, from litter under shrub.
Etymology. This specific epithet “ praeconcavus ” is a combination of “prae-” from the Latin for “anterior” and “concavus” from the Latin for “concaved”, which refers to the strongly concave anterior margin of prodorsal condyles of this species.
Diagnosis. Adult. Total length 665 Μm. Prodorsal setae ro, le and in slightly barbed distally, transverse ridge connecting insertions of le not indented medially. Anterior margin of prodorsal condyles strongly concave, almost U-shaped. Distance between intersections of inner margins of prodosal and humeral condyles longer than vertical distance between intersection of posterior margins of prodorsal condyles and anterior margin of notogaster. Ten pairs of notogastral setae present, thick, long, smooth and tapered. Surface of notogaster smooth.
Adult. Measurements: total length 665 Μm, notogastral length 420 Μm, notogastral width 450 Μm.
Prodorsum. Prodorsal setae ro, le and in barbed slightly on distal half (Figs. 5, 8); ro inserted dorsally on prodorsum; le inserted on tubercle anteriorly on lamella, arched transverse ridge (not indented) connecting tubercles (Fig. 5); in inserted near lateral margin of prodorsum; ro length 190 Μm, distance between ro 65 Μm, le length 180 Μm, distance between le 85 Μm, in length 165 Μm, distance between in 200 Μm. Bothridial seta curved, sickle-formed, weakly swollen in middle portion, length 205 Μm. Tutorium (tu) well developed, pointed distally. Pair of plate-shaped prodorsal condyles arise posterolaterally and extend anterior-medially to interlock medially, their mutual anterior margin curved backward strongly, almost U-shaped (Figs. 5, 16, 17), several small verrucous tubercles present on its anterior and lateral margins.
Notogaster. Pair of large triangular humeral condyles present and interlocking with prodorsal condyles. Area circumscribed by inner margin of condyles concave and approximately hexagon-shaped (Figs. 5, 17). Distance between intersections of inner margins of prodosal and humeral condyles (DIPN) longer than vertical distance between intersection of posterior margins of prodorsal condyles and anterior margin of notogaster (DVPN). Surface of notogaster smooth. Ten pairs of notogastral setae present, thick, long, smooth and tapered (Figs. 5, 7); setae c inserted on inner margin of humeral condyle, basal half directed anteromedially, distal half curved posteriorly (Figs. 5, 16). Setae length: c 170 Μm, la 100 Μm, lm broken, lp 110 Μm, h 1 100 Μm, h 2 105 Μm, h 3 100 Μm, p 1 55 Μm, p 2 65 Μm, p 3 105 Μm.
Ve nt e r. Setae ad 3 and ad 2 inserted almost at same level with anterior and posterior margin of anal opening, respectively, ad 1 inserted posterior to posterior margin of anal opening (Figs. 6, 7).
acters mentioned in the “Remarks” of L. carinatus described above. It differs from L. mirabilis by: in L. praeconcavus, anterior margin of prodorsal condyles strongly concave, almost U-shaped, distance between intersections of inner margins of prodosal and humeral condyles longer than vertical distance between intersection of posterior margins of prodorsal condyles and anterior margin of notogaster; in L. mirabilis, anterior margin of prodorsal condyles almost straight, distance between intersections of inner margins of prodosal and humberal condyles shorter than vertical distance between intersection of posterior margins of prodorsal condyles and anterior margin of notogaster. Differences between L. praeconcavus and L. carinatus are given in the “Remarks” of L. carinatus described above.