Lasioseius quinisetosus Lindquist & Karg

De, Jeferson L., Lindquist, Evert E. & De, Gilberto J., 2009, Edaphic ascid mites (Acari: Mesostigmata: Ascidae) from the state of São Paulo, Brazil, with description of five new species, Zootaxa 2024, pp. 1-32 : 17-19

Lasioseius quinisetosus Lindquist & Karg

( Figs 35–43 )

Lasioseius quinisetosus Lindquist & Karg in Christian & Karg, 2006: 128 (replacement name for Cheiroseius inguinalis Karg, 1977: 299 , junior homonym of Lasioseius inguinalis Karg, 1976: 533 ). Cheiroseius inguinalis Karg, 1977: 299 .

not Lasioseius inguinalis Karg, 1976: 533 .

Diagnosis: The adult female of this species resembles those of several species of Lasioseius described from the Southern Hemisphere (Africa, Australia, South America) in having the metapodal plates coalesced into one enlarged, subtriangular, reticulated plate on either side. It further resembles that of L. uluguruensis van Aswegen & Loots, 1969, in distinction to other species including L. inguinalis Karg, 1976 , in having only 4 (instead of 5 or 6) pairs of opisthogastric setae plus the 3 circum-anal setae on the ventri-anal shield, leaving setae ZV3, JV4, JV5 on soft cuticle flanking that shield. It differs from L. uluguruensis and others in lacking discrete platelets on the pre-sternal region and in having nearly all of the dorsal shield setae smooth, attenuate (only j1 and r3 are tricarinate) and relatively long, most of them clearly longer than distance to insertion of next seta in series.

Adult female. Dorsal idiosoma ( Fig. 35 ): Dorsal shield 580–588 µm long, 425–465 µm wide at midlength level of setae s6, embossed-reticulate over entire surface, lacking puncta posteriorly between setae Z4-J5; with 22 pairs of setae (j1-j6, z1-z6, s1-s6, r2-r5) on anterior region and 15 pairs of setae (J1-J5, Z1-Z5, S1-S5) on posterior region. Setae j1 (40–43 µm) and r3 (50–52 µm) lanceolate-tricarinate, all other dorsal shield setae slender, attenuate, most of them relatively long (58–88 µm), clearly longer than distance to insertions of next seta in series, though some of them, especially z1, s1, s2, r2, J5 (20–32 µm) and to lesser extent z2, z5 (35–42 µm), shorter; seta r4 ca. 0.6 as long as s4 neighboring it medially; insertion of seta z5 displaced slightly anterior to level of j5. Lateral soft cuticle with 12 to 15 pairs of setae, including 7 marginal pairs (r6, R1-R6) and 0 to 3 submarginal pairs (UR) below R4-R6, flanked by 5 pairs of opisthogastric setae ventrolaterally (see below), these setae attenuate, of moderate length.

Ve nt r a l idiosoma ( Fig. 36 ): Tritosternal laciniae free for ca. 80 µm of their length (115–120 µm). Presternal area strongly lineate, not microtuberculate, and containing first pair of sternal setae. Sternal shield densely punctate over most of surface, lineate-striate along lateral margins, lacking anteromedian patch of reticula, with second and third pairs of sternal setae and 2 pairs of poroids. Metasternal plates subquadrate, with fourth pair of sternal setae and third pair of poroids. Endopodal strips well formed alongside coxae III–IV. Genital shield truncated posteriorly, slightly widened behind genital seta, coarsely punctate over much of surface, slightly reticulate posteriorly; paragenital pores in soft cuticle well posterior to level of genital seta. Post-genital platelets consolidated into one transverse strip. Metapodal plates undivided, enlarged, reticulate, subtriangular, longer (85–97 µm) than wide (67–75 µm). Ventri-anal shield much wider (338–342 µm) than long (200–220 µm), with anterior margin slightly concave medially, embossed-reticulate over entire surface, lacking field of puncta in anal region; shield with 4 pairs of opisthogastric setae (JV1-JV3, ZV2) plus 3 circum-anal setae of which para - anals subequally as long as post-anal seta (25–30 µm); JV3 (55–57 µm) clearly longest of setae on shield. Ventral soft cuticle around ventri-anal shield with setae ZV1 flanking shield anteriorly and with 8 to 11 pairs of setae flanking shield postero-laterally, including 5 pairs of opisthogastric setae (ZV3-ZV5, JV4, JV5) flanked by marginals R4-R6 and 0-3 pairs of submarginals; other than short ZV1 (20 µm), all these setae moderately long, similarly attenuated, and individually inserted on sclerotized tubercles. Exopodal plate a wide continuous strip alongside coxae II–IV.

Peritrematal shield and peritreme ( Figs 35–36 ): Peritrematal shields fused to dorsal shield at level of setae r2 and contiguous with exopodal shields alongside coxae II–IV; peritremes extending anteriorly to bases of setae j1.

Spermathecal apparatus ( Fig. 37 ): Difficult to discern, apparently with a small (length 8 µm, width 8 µm) but well sclerotized cup-shaped calyx; embolus and minor duct barely discernible.

Gnathosoma ( Figs 38–41 ): Anterior margin of tectum with 3 weakly formed, irregularly denticulate prongs, the central one deeply subdivided in some specimens. Middle segment of cheliceral shaft elongate, much as in species of Cheiroseius (length ca. 190 µm, including the ca. 50 µm long fixed digit). Fixed cheliceral digit with short pilus dentilis, 2 offset subapical teeth beside a deep notch (to accomodate apical hook of movable digit) anterior to a row of ca. 15 minute teeth inserted on a convex ridge (ca. 11–13 µm in length) that apposes dentition of movable digit (much as in species of Cheiroseius ); movable digit (length 48–52 µm) tridentate, the central tooth larger; lateral hyaline rim along paraxial face of digit weakly serrated at level of base of movable digit. Deutosternum with 7 connected rows of fine denticles; anterior 5 rows each with ca. 25 denticles; 6th and 7th rows each with ca. 30 denticles. Hypostomatic setae h1 slightly thicker, longer (48–52 µm) than h2 (38–45 µm); internal mala slightly longer than corniculus, with lateral margin finely fringed. Palptrochanter with internal seta attenuated (35–40 µm), much longer than external seta (25 µm).

Legs ( Figs 42, 43 ): Leg I subequally as long as dorsal shield, leg IV slightly (1.1–1.2) longer (550–610 and 625–675 µm long, respectively); pretarsus of leg I long, thin (25–27 µm), pretarsi of legs II–III (15 µm) and IV (17–18 µm) shorter; claws of tarsus I smaller than those of other tarsi; tarsi II–IV with apical setal processes nearly half as long as pretarsi; pretarsi II–IV with thin attenuate paradactyli projecting well beyond apices of claws (15–17 µm on II–III, 20–25 µm on IV). Genua and tibiae of legs I-II-III-IV with 13-11-9-9 and 13-10-8-10 setae, respectively, without deficiencies. Tarsus II with seta pl -2 elongated (55–60 µm) but short of reaching base of pretarsus ( Fig. 43 ); tarsi III–IV without elongated setae. Tarsus IV (250–255 µm) ca. 1.4 as long as tarsi II–III (175–180 µm); leg IV setae pd -3 on basitarsus and pd -2 on telotarsus subequal in length (38–45 µm), ca. 0.5 as long as tibia (80–90 µm). All leg setae smooth.

Adult male: Unknown.

Material examined: Piracicaba – 3 female, 04.i.1999, from litter of a patch of secondary forest.

Previous records: Originally recorded from nematode probes from two sites in Chile, from substrate amidst grass roots and from algae of small pond ( Karg 1977).

Remarks: Although described as a species of Cheiroseius , some of the attributes in the original description of Karg (1977) indicate the proper placement of this species in the genus Lasioseius , especially: the tricarinate form of the humeral seta r3, the position of the para-anal seta beside (rather than behind) the anal opening, the greater length of the post-anal seta relative to the para-anals (generally shorter than the paraanals in Cheiroseius ), the enlargement of the metapodal plates (otherwise unknown among the many species of Cheiroseius and other platyseiine genera), and the rounded form of some of the pulvillar elements of tarsi II–IV that are typically acute in platyseiines. The examination by one of us (EEL, 2004) of a paratype female of Cheiroseius inguinalis confirmed the presence of other attributes characteristic of Lasioseius rather than Cheiroseius , including: the lack of flagellate-straplike form of the anterior hypostomatic seta and internal palptrochanter seta; the lack of straplike form of elongated seta pl -2 on tarsus II and the lack of similar elongation and form of seta ad -3 on tarsi II–IV, and a leg chaetotaxy fully holotrichous like most Lasioseius and other genera of Blattisociinae, rather than lacking seta v3 on femora I–II and pv -1 on genu II, which are definitive losses for genera of Platyseiinae ( Lindquist & Evans 1965).

When Christian & Karg (2006) transferred Cheiroseius inguinalis Karg into Lasioseius , as Lasioseius inguinalis ( Karg 1977) , this name became a junior homonym of Lasioseius inguinalis Karg, 1976 , which is the name for another, quite distinct species also described from Chile. One of us (EEL, 2004) has examined the holotype of this species also ( Figs 44–46 ). Adult females of this form have similarly enlarged metapodal plates but are distinct as follows: the caudal region of the dorsal shield and anal region of the ventri-anal shield are densely coarsely punctate (puncta not shown in Fig. 44 , see fig. 19c in Karg 1976); the dorsal shield setae are generally shorter and tricarinate-serrate; the sternal shield has a V-shaped patch of reticula anteromedially; the ventri-anal shield bears 6 pairs of opisthogastric setae (not 7 pairs as indicated by Karg, as JV5 is inserted on a tubercle in soft cuticle beside the incurved postero-lateral margin of the shield) ( Fig. 44 ); the cheliceral digits are smaller and with much different dentition, the fixed digit having 6 coarse, well separated teeth, and the movable digit (length 30 µm) quadridentate ( Fig. 45 ); the legs are shorter, with I and IV shorter than the idiosomal length (which is similar to that of Ch. inguinalis ), and with the tarsi markedly shorter (tarsi II–III 110–115 µm, IV 160 µm); the pretarsi of legs II–IV have short paradactyli ( Fig. 46 ). As a result, L. inguinalis ( Karg 1977) , was replaced by Lasioseius quinisetosus Lindquist & Karg in Christian & Karg, 2006: 128, and that name is used here.

Figures

FIGURES 35 – 43. Lasioseius quinisetosus Lindquist & Karg. Adult female, dorsal idiosoma (35), ventral idiosoma (36), spermathecal apparatus (37), tectum (38), ventral gnathosoma (39), chelicera (40 and 41), pretarsus IV (42) and tarsus II (43).

FIGURES 44 – 46. Lasioseius inguinalis Karg. Adult female, ventral idiosoma (44), chelicera (45) and pretarsus II (46, one paradactyl not visible).