Cheiroseius neophalangioides, De, Jeferson L., Lindquist, Evert E. & De, Gilberto J., 2009

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 : 4-7

Cheiroseius neophalangioides sp. nov.

( Figs 1–10 )

Diagnosis: Adults of this species are closely similar to those of Cheiroseius phalangioides Evans & Hyatt, 1960 in having leg IV much elongated, at least 1.5 times as long as the dorsal shield, absences of the third ventral seta on genu I and of seta pv on genua II and III, and in having stout, blade-like vertical setae j1 which project directly anteriorly. They are distinguished from the latter in having leg IV ca. 1.7–1.8 times as long as the dorsal shield, and the telotarsus of leg IV with seta ad -3 at least 3 times as long as other setae on this article, whereas leg IV is over twice (ca. 2.3–2.4) as long as the dorsal shield and ad -3 is similar in short length to other setae on tarsus IV in C. phalangioides .

Adult female. Dorsal idiosoma ( Fig. 1 ): Dorsal shield 375–390 µm long, 250–255 µm wide at level of setae j6, reticulated over entire surface except near posterior margin; vertical region of shield not protruding, but with vertical setae j1 prominent (33–35 µm), blade-like, projecting directly anteriorly; setae z1 (18–20 µm) slender, curved and directed laterally, ca. 0.7 as long as j2 (30–32 µm). Dorsal shield with 36 or 37 pairs of setae, 21 or 22 pairs on anterior region, 15 pairs on posterior region; first 3 pairs of marginal setae, r2-r4, on humeral region of shield; r5 and 5 pairs of R -marginals on lateral soft cuticle (in some specimens one or both r5 on dorsal shield), r6, UR -submarginals, and sometimes R2 absent. Most dorsal shield setae moderately long (40–50 µm), slightly longer than successive distances between their bases, Z4 reaching to bases of Z5, both of the latter of similar length (45–48 µm); other than j1, all setae attenuate, smooth except caudal pair J5 slightly barbed, short (14–15 µm); setae s1 (30 µm), s2 (33–35 µm), r2 (25–27 µm), r3 (30–32 µm), r4 (42 µm), and especially z5 (25–27 µm) shorter than adjacent setae. Setae on lateral soft cuticle moderately short (25–28 µm), simple.

Ve n t r a l idiosoma ( Fig. 2 ): Tritosternum with slender base (length 22 µm) and laciniae fused along basal one-fourth (22 µm) of their length (85–87 µm). Pre-sternal area sparsely lineated, without evident platelets. Sternal shield 85–87 µm in median length by 79–82 µm wide at narrowest width between coxae II, with 3 pairs of setae and 2 pairs of poroids; shield with prominent endopodal projections between coxae I and II, but separated from endopodal strips between coxae II and III and scarcely widened at that level, such that second pair of poroids on postero-lateral edges of shield; sternal shield with conspicuous patch of reticula anteromedially, faintly, irregularly punctate laterally, nearly smooth posteriorly; posterior margin gently concave. Third pair of sternal poroids with sternal setae st4 on metasternal plates. Sternal setae st4 (15–16 µm) slightly shorter than st3 (17–18 µm). Pair of thin endopodal strips alongside coxae III–IV continuous anteriorly with those projecting between coxae II–III. Genital shield lightly reticulated over most of surface, greatest width (78–80 µm) at level of insertions of genital setae, with lateral margins emarginated posteriorly, at level of paragenital gland pores, posterior margin truncate, apex of hyaline anterior margin narrowly rounded, not or barely overlapping posterior margin of sternal shield. Post-genital strip continuous, slightly widened on either side into a platelet. Metapodal plates well separated from posterior margin of peritrematal shield, undivided, small, slender, ca. 20 µm long by 5 µm wide. Ventri-anal shield subtriangular, ca. 0.8 as long as wide (112–119 µm long by 145–150 µm wide), its anterior margin convex; shield reticulated over nearly entire surface, without punctate areas; with 3 pairs of opisthogastric setae (JV2, JV3, ZV2) in addition to 3 circum-anal setae, all simple; JV2 and JV3 similar in length (23–27 µm), slightly longer than ZV2 (20–21 µm); para-anal seta (15–17 µm) slightly longer than post-anal seta (13–15 µm). Seven pairs of opisthogastric setae on soft cuticle flanking ventri-anal shield, JV1, ZV1 anteriorly and JV4-JV5, ZV3-ZV5 laterally, the latter flanked by posterior 2 or 3 pairs of R -marginals on soft cuticle.

Peritrematal shield and peritreme ( Figs 1–2 ): Peritrematal shields united with dorsal shield at position of paravertical poroids and level of setae j2; peritremes extending to bases of setae z1, their anterior extremities well separated from each other; peritreme not noticeably thickened (width ca. 10 µm), not wavy or crenulated, and lacking poststigmatic extension; exopodal plate strip not consolidated with peritrematal shield alongside coxae II–III, but integrated with it beside and behind coxa IV.

Spermathecal apparatus ( Fig. 3 ): With a short unsclerotized major duct leading from solenostome to a small (greatest dimension ca. 7–10 µm), dense sac-like structure bearing 2 protrusions and an embolus with a minor duct ending in a capitate enlargement.

Gnathosoma ( Figs 4–6 ): Anterior margin of tectum usually 3-tined, mid-tine longer and slenderer than lateral tines. Fixed digit of chelicera with short (ca. 3 µm) pilus dentilis and with large offset subapical tooth followed by short ridge (length ca. 5 µm) with 5–7 fine denticles; movable digit 18–20 µm long, with 2 weakly developed teeth in apposition to denticulate ridge of fixed digit. Deutosternum with 7 free-standing, multidenticulate rows of denticles, fifth and sixth rows slightly wider than others, interval between fifth and sixth rows ca. 1.3 times longer than that between fourth and fifth rows; corniculus normally formed, reaching nearly midlevel of palpfemur; internal mala finely fringed, slightly longer than corniculus. Anterior hypostomatic setae (38–40 µm) and internal palptrochanter seta (48–50 µm) elongated, flagellate, the latter extending nearly to apex of palpgenu; external palptrochanter seta short (ca. 20 µm), poorly tapered.

Legs ( Figs 7–8 ): Leg I (408–432 µm) slightly shorter and legs II (332–342 µm) and III (345 µm) clearly shorter than dorsal shield; leg IV elongated (670–675 µm), ca. 1.7–1.8 longer than dorsal shield, sometimes bowed ventrally (especially the femoral and tarsal segments). Leg I with tarsus (105–110 µm) ca. 1.2–1.3 longer than tibia (80–83 µm) and nearly 1.9 longer than genu (55–60 µm); setae on tarsus I slender, none thickened or greatly elongated (most basal dorsal seta, 30–32 µm, more attenuated and slightly longer than mid-dorsal seta, and one apical pseudosymmetric pair moderately elongated, ca. 50–55 µm, several other subapical ones 35–40 µm), specialized subapical sigmoid seta moderately elongate (ca. 25 µm); claws on short but well developed pretarsus (8–10 µm), claws well developed (length 8–9 µm), nearly as large as those on tarsus IV (10 µm) though smaller than those on legs II–III (12–14 µm). Pretarsi of legs II, III, IV of moderately increasing length (12, 15, 20 µm, respectively), with claws flanked by flagellate paradactyli (20–22 µm), these ca. twice as long as claws; pulvillus with median lobe broadly acute (ca. 15–20 µm), lateral lobes rounded; tarsi II–IV with apical setal processes ad -1, pd -1 moderately elongated (20–25 µm), whip-like, not inflated basally; telotarsus II with generically typical, elongate-flagellate seta ad -3 (ca. 50 µm), pl -2 (ca. 40 µm) and whip-like but not flagellate seta pd -3 (ca. 40 µm), and telotarsus III with typically elongateflagellate setae ad -3 (ca. 45 µm) and pd -3 (ca. 55 µm); telotarsus IV with seta ad -3 whip-like but only moderately long (55–60 µm), shorter than basitarsus, and with mid-dorsal lyrifissure parallel to length of leg, beside base of ad -3; basitarsus IV longer (70 µm) than basitarsi II, III (30, 35 µm). Setation of femora of legs I-II-III-IV, respectively, 11-10-6-6; that of genua, 12-10-8-9; that of tibiae, 13-10-8-10; femora I–II lacking seta v -3, genu I lacking v -3, genua II-III lacking pv. Other than whip-like setae on tarsi II–IV and some apical setae on tarsus I, leg setae generally moderately short (15–30 µm) and smooth, al -1 of telofemur and al -2 of basifemur of leg II bluntly spinelike, very short (5 µm).

Adult male. Dorsal idiosoma: Dorsal shield 270–275 µm long, 200–205 µm wide at level of setae j6, ornamented as in female but with more expansive lateral margins that bear all marginal setae present, such that 22 pairs of setae (including r4-r5) on anterior region and 18 pairs (including 3 pairs of R -setae) on posterior region; R2-R3 absent (one member of most posterior pair of R -setae sometimes on lateral soft cuticle). Form and proportionate size of dorsal idiosomatic setae much as in female, general lengths along with idiosomal length ca. 25 % shorter than in female.

Ve n t r a l idiosoma ( Fig. 9 ): Tritosternum proportionally smaller than in female, with laciniae fused along basal 0.4 of their length (60 µm). Sternogenital shield 125–130 µm long, 65–67 µm wide at narrowest widths between coxae II–IV, with 5 pairs of setae and 3 pairs of poroids, unornamented over most of surface, lineate along lateral margins; setae st4 not suppressed but shorter (10–11 µm) than st1-st3 (15–17 µm). Ventri-anal shield length 87–90 µm, extending over areas occupied by metapodal plates, abutting posterior margin of sternogenital shield and posterior margins of peritrematal-exopodal plates (separation of these structures as shown in Fig. 9 caused by slide-mounting), but not united caudally with dorsal shield; ventri-anal shield transversely lineate-reticulate over nearly entire surface, bearing the only 3 or 4 pairs of opisthogastric setae present, JV1, ZV2, JV5, sometimes JV4 (JV2-JV3, ZV1, ZV3, sometimes JV4 repressed).

Peritrematal shield and peritreme: Peritrematal shields united with dorsal shield at level of setae r3; form and extent of peritreme as in female.

Gnathosoma: Form of tectum and ventral subcapitular structures similar to those of female; distance between fifth and sixth rows of deutosternal denticles ca. 1.3–1.5 longer than that between fourth and fifth rows. Fixed digit of chelicera with file of ca. 12 fine denticles between subapical tooth and pilus dentilis, this file not on elevated ridge as in female; movable digit 32–34 µm long, with one well-formed tooth in apposition to file of denticles on fixed digit; spermatodactyl 32–33 µm long, extending ca. 15 µm beyond tip of movable digit, simple in form, thickened and with slight spur paraxially along midlength, curved slightly downwards apically ( Fig. 10 ).

Legs: Relative to idiosomatic length, leg lengths similarly proportionate to those of female; leg I 330–340 µm, leg II 255–270 µm, leg III 265–280 µm, leg IV 500–515 µm. Leg I with tarsus (90–92 µm) ca. 1.4–1.5 longer than tibia (62–65 µm) and ca. twice longer than genu (44–45 µm). Setation and other structures of legs similar to those of female, no sexual dimorphism evident.

Material examined: Holotype female, paratype male, 1 paratype female and 1 paratype male, 18.iv.2000, from forest litter, Cananéia, State of Sao Paulo, col. A. R. Oliveira, deposited at ESALQ-USP. One paratype female and 1 paratype male, same data as holotype, deposited at Canadian National Collection of Insects and Arachnids, Ottawa, Ontario, Canada ( CNCI).

Remarks: One of us (EEL) is aware of at least four other species, as yet undescribed, from Central America and southern Mexico, whose adults also display the synapomorphic attributes of absences of the ventral setae v -3 on genu I and pv on genua II and III, elongated leg IV, bladelike, anteriorly-projecting vertical setae and whose females usually (in three of the four species) have a relatively small, subtriangular ventri-anal shield. This group of species may be considered to form the phalangioides species group. This is the second record of a member of this species group from South America. Mineiro & Moraes (2001) referred to the occurrence of C. phalangioides in Piracicaba, also in the state of São Paulo, Brazil. A re-examination of those specimens showed that they are actually C. neophalangioides sp. nov.. Cheiroseius phalangioides was originally described and recorded by Evans & Hyatt (1960) from tropical Africa. The subsequent record of it from Japan by Ishikawa (1969) is uncertain, in view of the previous lack of attention given to certain details such as the length of leg IV relative to the length of the dorsal shield, and the relative lengths of some leg setae, particularly on tarsus IV.

Etymology: The name neophalangioides refers to the close similarity between the new species here described and C. phalangioides .

Figures

FIGURES 1 – 10. Cheiroseius neophalangioides n. sp. Adult female, dorsal idiosoma (1), ventral idiosoma (2), spermathecal apparatus (3), tectum (4), chelicera (5), ventral gnathosoma (6), pretarsus III (7) and tibia and tarsus IV (8). Adult male, ventral idiosoma (9) and spermatodactyl (10).