Proctolaelaps paulista, 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 : 22-25

Proctolaelaps paulista sp. nov.

( Figs 51–57 )

Diagnosis: Adult females of this species resemble those of Proctolaelaps intermedius Athias-Henriot 1959 and similar forms (see remarks below) in having usually one or rarely two pairs of opisthogastric setae (JV2, sometimes JV1 or JV4) in addition to the circum-anal setae on a ventri-anal shield that is widest near its anterior margin, a triramous tectum, the anterior hypostomatic setae thickened, and the dorsal shield ornamented with few diagonal lateral striae on the anterior region. The dorsal shield in P. paulista differs in having a pair of deep podonotal incisions between setae s1 and s2 that extend nearly to the bases of setae z2, the opisthonotal region fully ornamented with transverse striae, with 20 pairs of opisthonotal setae including R1-R5, setae Z5 distinctly stouter than neighboring opisthonotal setae, the sternal, genital and ventri-anal shields fully reticulated, the palptarsal apotele 2-tined, the corniculus tricuspidate apically, and the chelicerae with a moderately multidenticulate fixed digit with 12 or 13 teeth, and a tridentate movable digit that lacks a proximal ridge of denticles. Those of P. intermedius and similar forms lack the deep podonotal incisions, have the posterior region of the dorsal shield unornamented, with 19 pairs of opisthonotal setae including R1-R4, setae Z5 similar in form to Z4 and S5, the ventral shields unornamented, the palptarsal apotele clearly 3-tined, the corniculus bicuspidate apically, and the chelicerae with a more finely multidenticulate fixed digit with 18–20 teeth, and a tridentate movable digit that is also provided more basally and paraxially with a ridge of 8 –10 fine denticles that appose similar denticles on the fixed digit (see Remarks).

Adult female. Dorsal idiosoma ( Fig. 51 ): Dorsal shield 305–315 µm long, 182–190 µm wide at level of setae j6, with few diagonal striae laterally on anterior region but fully covered with light, mostly transverse striae on posterior region; antero-lateral margins of shield with pair of deep clefts between setae s1 and s2 that extend nearly to bases of setae z2. Dorsal shield with 43 pairs of setae, 23 pairs including marginals r2-r6 on anterior region, 20 pairs including marginals R1-R5 on posterior region; marginal R6 inserted somewhat ventrolaterally on posterior soft cuticle; submarginal UR setae absent. Most dorsal shield setae moderately short (15–22 µm, except z1, s1, J5 and all R -setae slightly shorter, 11–14 µm), generally shorter than successive distances between their bases, J3 and Z3 reaching 0.6–0.7 of distance to bases of J4 and Z4 respectively, S3 ca. 0.5 as long as interval S3-S4; all setae smooth, slender, except Z5 longer (34–35 µm), thicker, slightly barbed.

Ven t ra l idiosoma ( Fig. 52 ): Tritosternum with slender base (length 10 µm) and laciniae fused along basal 15 µm of their length (50–55 µm). Pre-sternal area transversely lineate, without evident platelets. Sternal shield 80–84 µm in median length by 72–75 µm wide at narrowest width between coxae II, with 3 pairs of setae, 2 pairs of poroids, and nearly straight posterior margin; shield reticulated over entire surface, with prominent endopodal projections between coxae I and II, and fully connected with more densely sclerotized endopodal strips between coxae II and III. Third pair of sternal poroids with sternal setae st4 on small metasternal plates. Sternal setae similar in form, st1 (29–30 µm) slightly longer and st3 slightly shorter (24–25 µm) than st2 and st4 (26–27 µm). Pair of thin endopodal strips alongside coxae III–IV connecting anteriorly with those of sternal shield projecting between coxae II–III. Genital shield reticulated over nearly entire surface, well widened behind level of insertions of genital setae such that greatest width (75–80 µm) at level of slightly convex posterior margin whose corners may touch openings of paragenital gland pores; hyaline anterior margin of shield broadly rounded, overlapping posterior margin of sternal shield. Post-genital furrow without evident platelets. Metapodal plates divided into smaller inner pair (length 5–7 µm) and larger outer pair (15–18 µm). Ventri-anal shield cup-shaped, leaving only narrow transverse strip of soft cuticle bearing setae JV1 and ZV1 between it and genital shield, its greatest width (81–85 µm) at nearly straight anterior margin ca. 0.9 as long as its length (90 µm); shield transversely striated anteriorly, reticulated posteriorly, with enlarged anal opening (length ca. 30 µm); shield with one (JV2) or sometimes asymmetrically 2 (JV4) pairs of opisthogastric setae plus 3 circum-anal setae, all simple, JV2 slightly the longest (26–27 µm); para-anal seta subequally as long as post-anal seta (21–23 µm). Eight or 9 pairs of opisthogastric setae on soft cuticle around ventri-anal shield include JV1, JV3, JV5, ZV1-ZV5 and usually JV4, these similar in size (12–18 µm, except JV1 and JV5 slightly longer, 19–21 µm) and flanked laterally by marginal pair R6 (resembling a submarginal UR -seta); setae SV1 absent. Exopodal plate a continuous strip alongside coxae II–IV, not consolidated with peritrematal shield alongside coxae II–III, but moderately broadly connected with latter beside and behind coxa IV.

Peritrematal shield and peritreme ( Figs 51–52 ): Peritrematal shields fused to dorsal shield at level slightly anterior to setae s1; peritremes extending to bases of setae z1.

Spermathecal apparatus ( Fig. 53 ): Not clearly discernible in specimens at hand; a short unsclerotized major duct leading from solenostome between coxae III and IV to a weakly sclerotized tubular portion (length ca. 10 µm, distal width ca. 8 µm) evident in paratype.

Gnathosoma ( Figs 54–56 ): Anterior margin of tectum triramous, lateral tines slender, slightly serrated apically, medial tine triangular, broader basally, simply pointed apically. Fixed digit of chelicera with row of 12–13 teeth, the more distal ones slightly larger and more spaced than the proximal ones, with hyaline-lobed pilus dentilis, and with hyaline weakly serrated rim near base on paraxial face; movable digit 20 µm long, tridentate, with basal paraxial ridge lacking teeth in apposition to proximal teeth of fixed digit, and with single prominent ventral mucro near base. Deutosternum with 6 rows of denticles, rows 1–5 connected; anterior 4 rows each with 2–5 denticles, fifth row widened with 10–15 denticles, 6th row widened with ca. 20–25 denticles, 7th row vestigial, indicated by concave line without denticles; corniculi slender, nearly parallel to each other, with trifid tips; internal mala fringed laterally, ca. as long as corniculus. Anterior hypostomatic setae very thick, longer (24–25 µm) than slender pairs h2–h3 which are similar in length (17–18 µm); basal palpcoxal pair much longer (25 µm). Palptarsal apotele 2-tined.

Legs ( Fig. 57 ): Legs I (325–337 µm) and IV (390 µm) longer, and legs II (215–230 µm) and III (230–240 µm) clearly shorter than dorsal shield. Pretarsi of legs I–III of similar length (15–17 µm), that of IV longer (25 µm), with normally developed claws; tarsi II–IV with apical setal processes ad -1, pd -1 inconspicuous (12–13 µm), and with ventral and subapical setae not thickened or spinelike. Coxae of all legs lineate ventrally; anterodorsal edge of coxa I with ridge of 6–8 serrations. Setation of genua of legs I-II-III-IV, respectively, 13- 11-9-9; that of tibiae, 13-10-8-10; leg chaetotactic formulae holotrichous for genus and tribe Melicharini as presented by Lindquist & Evans (1965); leg setae slender, smooth, of generally similar size, without evident macrosetae (but see below). Leg IV with tarsal seta md as long as length of tibia (60 µm), and slightly longer than distance from its insertion to base of pretarsus (50 µm); alveoli of setae pd -2 and pd -3 on elevated bases and with diameters slightly larger (3.0–3.5 µm) than those of other setae (2.0–2.5 µm) on tarsus IV, possibly indicating bases of macrosetae (shafts missing on specimens at hand).

Adult male: Unknown.

Material examined: Holotype female, 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. One paratype female, same collection data as holotype, deposited at CNCI.

Remarks: P. paulista is at least facultatively fungivorous, as indicated by the presence of fungal fragments in the gut cavity of the holotype specimen. The apically toothed corniculi, thickened anterior hypostomatic setae and enlarged anal opening are also indicative of fungivory. Our anticipation that setae pd - 2 and pd - 3 may be macrosetae on tarsus IV in P. paulista is supported by our observations of the same setae on leg IV in P. intermedius , in which pd -2 (ca. 40 µm) and pd -3 (ca. 35 µm) are shorter than the tibia (length ca. 50 µm) and lack enlarged alveoli.

One of us (EEL) has examined the type material of P. intermedius as well as that of two other species of Proctolaelaps originally named Neojordensia orientalis ( Chant, 1963) and Neojordensia wenkochingi Samšinák, 1964 . Adult females of these species are alike in all descriptive aspects, including the peculiar dentition of the movable cheliceral digit, which was not noted in the original descriptions for these forms ( Figs 58, 59 ) (see below). The form of the ventri-anal shield among these species varies considerably among females of the same population and in any case does not differ visually between the named species as much as shown by Karg (1985, fig. 10). Among the type specimens of P. intermedius as well as the holotypes of P. orientalis and P. wenkochingi , the ventri-anal shield may carry one pair, or asymmetrically a third seta, or symmetrically two pairs of “pre-anal” setae, due to considerable variation in the position of seta JV1 either on the anterior margin, or touching that margin, or clearly within the margin of the shield. As a result, these species are here placed in synonymy, with P. orientalis , new synonym and P. wenkochingi new synonym treated as junior subjective synonyms of P. intermedius . Proctolaelaps ventrianalis Karg, 1971 is also thought to be conspecific and a junior synonym of P. intermedius , but we have not studied its type material to determine the attributes of the movable digit.

The peculiar nature of the dentition of the movable digit in P. intermedius and related forms was not given attention in the original or subsequent descriptions of those species. The secondarily dentate ridge on the basal paraxial surface of the movable digit in apposition to the similarly fine dentition proximally on the fixed digit ( Figs 58–59 ) may be a further adaptation for fungivory.

Some additional females identified as P. intermedius by Athias-Henriot apparently subsequently to her original description of that species, and deposited as reference specimens with the type material of that species, are clearly of a different, and apparently undescribed, species that is more similar to the one newly described here. Those on slides labeled W383 and V331 have the dorsal, sternal, genital and ventri-anal shields fully reticulated; the dorsal shield setae are collectively long, much longer than the intervals between their bases; the ventri-anal shield is widest at the anus, tapered anteriorly, and bears only pre-anal seta JV2 on its antero-lateral corners; the corniculus is apically tricuspidate; the palpal apotele 2-tined; the fixed cheliceral dentition begins with 2 large coarse teeth basally; and leg IV tarsal setae pd -2 (58 µm) and pd -3 (44 µm) are not conspicuous as macrosetae relative to the tibial length (55 µm).

Karg (1979, 1985, 1988) recognized 3 subgenera of Proctolaelaps , of which Paraproctolaelaps Bregetova (1977) was defined by the female having a ventri-anal shield, and Proctofissus Karg (1979) by its adults having the corniculus divided, or multicuspidate, distally. The phylogenetic value of these distinctions is doubtful and they are not followed here, in part because the nominate subgenus is not defined apomorphically, but also because some species, including P. intermedius , P. wenkochingi and P. orientalis , have the apomorphic attributes of both of the other subgroups. Also, Proctofissus is an unavailable name, according to the International Code of Zoological Nomenclature, as no type species was designated ( Halliday et al. 1998).

Etymology: The name paulista corresponds to “from the State of São Paulo, Brazil ”, and refers to the place where the type specimens of this species were collected.

Figures

FIGURES 51 – 59. Proctolaelaps spp.: P. paulista n. sp. Adult female, dorsal idiosoma (51), ventral idiosoma (52), spermathecal apparatus (53), tectum (54), chelicera (55), ventral gnathosoma (56) and tarsus IV (57). P. intermedius Athias – Henriot. Chelicera (58). P. wenkochingi (Samsinak). Chelicera, holotype female (59).