Protogamasellus sigillophorus, 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 : 26-29

Protogamasellus sigillophorus sp. nov.

( Figs 60–67 )

Diagnosis: Adult females of this species are similar to those of Protogamasellus massula ( Athias-Henriot, 1961) and P. scuticalis Genis et al., 1967 in having opisthogastric setae ZV1 inserted behind, and in longitudinal alignment with, JV1 on soft cuticle and in having a pyriform ventri-anal shield that is longer than wide, with 3 pairs of opisthogastric setae (JV2, JV3 and JV5) in addition to the circum-anal setae. They differ from the latter two in a variety of aspects, particularly the opisthonotal shield having setae J4 relatively short (i.e., only 1.3 instead of 2.0 longer than J5), and the simply bidentate movable digit, with the proximal tooth much larger than the subapical tooth.

Adult female. Dorsal idiosoma ( Fig. 60 ): Dorsal shields collectively 270–305 µm long and unornamented other than podonotal shield having an uninterrupted transverse line at level of setal bases z6 and s6, behind which shield desclerotized, and opisthonotal shield having an uninterrupted transverse line at level of setal bases J1, followed by a couple of short transverse lines laterally near bases of setae Z1 and S1 and a median sigillar scar between bases of setae J1 and J2. Podonotal shield 130–148 µm long, 98–102 µm wide at level of setae j5, with 17 pairs of setae, opisthonotal shield 138–152 µm long, 65–68 µm wide at level of setae J2, (ca. 2.1–2.2 times as long as wide) with 15 pairs of setae; 12 pairs of setae on lateral soft cuticle, including s2 and r2-r5 anteriorly (r6 absent) and R1-R6 and one submarginal UR seta posteriorly. Podonotal shield with vertical setae j1 prominent, stouter and longer (25–27 µm) than other setae (11–16 µm) which shorter than successive distances between their bases; on opisthonotal shield J3 (12–14 µm) ca. 0.3–0.4 times as long as alveolar interval J3-J4, J5 (9–10 µm) shorter than other members of J -series (12–16 µm), Z1-Z4 similar in length (15–18 µm) and 0.6–0.7 as long as alveolar interval to next seta in series, Z5 conspicuously longer (28–30 µm); S1-S4 similar in length (11–12 µm) and 0.4–0.5 as long as interval to next seta in series, S5 slightly longer (14 µm); all setae smooth except J4, Z5 and S5 sparsely barbed. Setae j2 transversely aligned with j1 and z1. Setae on lateral soft cuticle short (10–13 µm, except r3 15 µm), simple.

Ve n t ra l idiosoma ( Fig. 61 ): Tritosternum normal in shape, with trapezoidal base and slender, pilose laciniae fused along basal one-fifth of their length (60–70 µm). Pre-sternal area weakly sclerotized, microtuberculate, without platelets. Sternal shield ca. 75 µm in median length by 45 µm wide at narrowest width between coxae II, with 3 pairs of setae and 3 pairs of poroids; shield with anterior margin deeply emarginated medially, faintly lineated along lateral margins, smooth over rest of surface, and with posterior margin gently concave. Setae st4 inserted on soft cuticle closely behind postero-lateral corners of sternal shield, st4 and genital setae st5 (10–12 µm) slightly shorter than sternal setae st1-st3 (14–16 µm). Endopodal plates formed as weak strips alongside coxae III–IV, not discernible in some specimens. Genital shield smooth, not widened at level of insertions of genital setae, with posterior margin truncate, and hyaline anterior margin broadly rounded, reaching posterior margin of sternal shield. Post-genital groove without discernible sigillar platelets. Metapodal plates hardly discernible as short, narrow strips (length 10 µm) laterad JV1. Ventri-anal shield pyriform, ca. 1.2 as long (87–97 µm) as wide (65–75 µm), with anterior margin arched; with 2 or 3 transverse lines arched anteriorly between bases of setae JV2 and para-anals (lines sometimes interrupted medially), and sparsely punctate on post-anal region; shield with 3 pairs of ventral setae (JV2, JV3, JV5) plus 3 circum-anal setae; post-anal seta and JV5 sparsely barbed and considerably longer (33–36 µm and 21–23 µm, respectively) than smooth para-anals (14–16 µm) and JV2-JV3 (11–14 µm); para-anals inserted at level of anterior margin of anus. Three pairs of ventral setae (JV1, ZV1, JV4) on soft cuticle anterior and lateral to ventri-anal shield; ZV1 nearly aligned vertically behind JV 1 in front of anterior margin of shield. Exopodal plate strips reduced to triangular fragments between coxae II and III, and between coxae III and IV, not discernible in some specimens.

Peritrematal shield and peritreme ( Fig. 60–61 ): Peritrematal shield interrupted between levels of setal alveoli r3 and s2, with separate triangular anterior piece abutting but not fused to dorsal shield at level of paravertical poroids and setae z1; peritrematal shield narrow posteriorly, not fused to exopodal fragments alongside coxae II–IV; peritremes extending to bases of setae r3.

Spermathecal apparatus: Unsclerotized, not discernible in specimens at hand.

Gnathosoma ( Figs 62–64 ): Anterior margin of tectum denticulate, irregularly triangular. Fixed digit of chelicera with pilus dentilis, with large offset subapical tooth and row of 11–13 evenly sized and spaced teeth; movable digit 35 µm long, with 2 well separated, slightly retrorse teeth, the proximal larger than subapical one. Deutosternum with 7 narrow, connected rows of denticles, anteriormost 2 or 3 rows with single median denticle, other rows with 2–4 denticles; corniculus stout, reaching to mid-level of palpfemur; internal mala slender, with lateral margin slightly fimbriate, hardly widened basally, extending to tips of corniculus. Hypostomatic setae h1 (20 µm) similar in slender form to, but longer than, h2 (15 µm). Palptrochanter with apical seta slightly stout, rigid, inserted on low prominence.

Legs ( Figs 61, 65–67 ): Leg I (268–275 µm) nearly as long as combined length of the 2 dorsal shields; legs II (163–168 µm), III (132–140 µm) and IV (200–212 µm) considerably shorter, with III notably smaller than II. Coxa I with cluster of 2–4 small spine-like processes on dorsal distal margin, and sparsely lineate ventrally; coxa II with 2 lines posteroventrally; coxae III–IV unornamented (processes and lines of coxae I and II not shown in Fig. 61 ). Legs I–IV with normally developed pretarsi (length ca. 5 µm on I, 8–11 µm on II–IV) and claws. Tarsi II–IV with apical setal processes ad -1, pd -1 inconspicuous, thin (length ca. 10 µm). Leg IV with tarsus (47–50 µm) ca. 2.3 as long as tibia (35–38 µm); tarsus IV with seta ad -2 (also denoted as md) (22 µm) and ad -3 (27–30 µm) erect and longer than other setae on same segment ( Fig. 67 ). Setation of femora of legs I-II-III-IV, respectively, 12-11-6-6; that of genua, 13-11-8-8 (pv -1 absent on genu III, pl -1 absent on genu IV); that of tibiae, 13-10-8-9 (pl -2 absent on tibia IV); leg setae smooth, mostly slender, except ad -3 on femur I, ad -2, ad -3 on femur II, and ad -2, pd -1, pl -1 of femur IV short, spine-like, and av -2, to lesser extent other ventral setae on tarsus II ( Fig. 65 ) and av -2, pv -2, mv on tarsus IV thickened, spinelike ( Fig. 67 ).

Adult male: Unknown.

Material examined: Holotype female collected, 2.x.1998, from soil of a corn field, ESALQ-USP, Piracicaba, State of São Paulo, col. J.L. de C. Mineiro, deposited at ESALQ-USP. Three paratype females including two with same data as holotype and one with same data except that collected on 21.xii.1998, two deposited at ESALQ / USP and one deposited at CNCI.

Remarks: Our description of this species as distinct from P. massula is based in part on notes taken by one of us (EEL, unpublished, 1972) during a study of Athias-Henriot’s type material as well as on the subsequent redescription of that species by Evans (1982). The setal deficiencies noted for genua III–IV and tibia IV in the above description are typical for the leg chaetotaxy of the genus Protogamasellus as indicated by Lindquist & Evans (1965) and further noted by Evans (1982).

Etymology: The name sigillophorus refers to the presence of median sigillar scar between the bases of setae J1 and J2.

Figures

FIGURES 60 – 67. Protogamasellus sigillophorus n. sp. Adult female, dorsal idiosoma (60), ventral idiosoma (61), tectum (62), chelicera (63), ventral gnathosoma (64), ventral tarsus II (65), dorsal tarsus II (66) and tibia and tarsus IV (67).