Leioseius basis Karg
Creators: name: Santos, Jandir C.
name: De Moraes, Gilberto J.
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Mesostigmata
Ascidae
Leioseius
Leioseius basis

description: Leioseius basis Karg
Leioseius basis Karg, 1994: 206.
Specimens examined. Holotype female, one paratype female and two paratype males collected by W. Karg at Bartolome, Galapagos Islands, February 12, 1985 from litter and sand and deposited at Museums fur Naturkunde, Berlin, Germany.
Adult female (Figs. 15–21) (Two specimens measured).
Gnathosoma. Antiaxial and dorsal lyrifissures as well as dorsal seta distinct (Fig. 15); fixed cheliceral digit 40–42 long, with six teeth in addition to apical tooth and a minute setiform pilus dentilis; movable cheliceral digit 38–39 long, with two teeth in addition to apical tooth. Palp setae (trochanter to tibia): 2-5-6-13; all setae aciculate and smooth. Anterior region of epistome with three short extensions, each 1–3-tined (Fig. 16). Deutosternum delimited by lateral lines, with anteriormost transverse line smooth followed by six transverse lines of denticles, about parallel to each other, each with 9–18 denticles; corniculus horn-shaped, about 25–26 long (from median level of base to tip) and 15–16 wide basally; seta h 2 about transversely aligned with h 3 (Fig. 17). Measurements of setae: h 1 20, h 2 20, h 3 18–20, pc 20.
Dorsal idiosoma (Fig. 18). Dorsal shield 355–380 long and 175–225 wide at widest level. Podonotal and opisthonotal shields fused, without lateral incisions at region of fusion. Podonotal region with 23 pairs of setae (j 1– j 6, z 1– z 6, s 1– s 6 and r 2 – r 6) and three pairs of distinguishable lyrifissures. Opisthonotal region with 15 pairs of setae (J 1– J 5, Z 1– Z 5, S 1– S 5), ten pairs of distinguishable lyrifissures and one pair of distinguishable pores. Unsclerotised cuticle along lateral margins apparently with five pairs of setae (R 1– R 5). Setal measurements: j 1 11– 12, j 2 12–13, j 3 13–15, j 4 14–15, j 5 14–15, j 6 13–15, J 1 14–15, J 2 16, J 3 15–16, J 4 15-17, J 5 11–10, z 1 12, z 2 11– 13, z 3 12–13, z 4 12–14, z 5 14–15, z 6 13–15, Z 1 15, Z 2 15, Z 3 15–16, Z 4 16–20, Z 5 20–21, s 1 11, s 2 11 –12, s 3 11– 12, s 4 12–13, s 5 13–15, s 6 14–15, S 1 15–16, S 2 15, S 3 16–20, S 4 20, S 5 18–20, r 2 13–14, r 3 13–14, r 4 13, r 5 11– 12, r 6 12–13, R 1 11–12, R 2 12–14, R 3 11–12, R 4 12–13, R 5 13. Most dorsal setae dagger-shaped and smooth (Fig. 19).
Ventral idiosoma (Fig. 20). Base of tritosternum 10 long and 15 wide proximally (Fig. 21); laciniae 95 (95– 95) long, separated for about 75% of their total length, pilose along about 85% of the divided section. Pre-sternal platelets lightly sclerotised, barely distinguishable in most specimens. Sternal shield 88–90 long at mid-line and 90–98 wide between setae st 1 and st 2, smooth; posterior margin slightly concave; with two pairs of setae (st 2 and st 3) and three pairs of lyrifissures (iv 1– iv 3); st 1 inserted on lightly sclerotised presternal platelets. Seta st 4 inserted on unsclerotised cuticle. Genital shield smooth, apex of hyaline anterior region rounded, posterior margin truncate; widened posteriorly to include st 5 and iv 5, distance st 5- st 5 48-50. One pair of elliptical metapodal plates. Ventrianal shield subtrapezoidal, 107–122 long at mid-line and 144–150 wide at widest level; with six pairs of setae (Jv 2– Jv 5, Zv 2, Zv 3) (one specimen with Zv 3 inserted on unsclerotised cuticle on one side) in addition to circumanal setae; post-anal seta slightly longer than para-anal seta, the latter inserted at about same level as posterior margin of anal opening. Without distinct platelets between genital and ventrianal shields. Usually with two pairs of opisthogastric setae on unsclerotised cuticle flanking ventrianal shield (Jv 1 and Zv 1). Anterior section of endopodal plate fused with sternal shield; posterior section indistinguishable. Measurements of setae: st 1 20–21, st 2 20–21, st 3 17–21, st 4 20–21, st 5 20–22; Jv 1 20, Jv 2 20–21, Jv 3 20–22, Jv 4 12–13, Jv 5 20–21, Zv 1 16–20, Zv 2 17–21, Zv 3 13–15, para-anal 20–21, post-anal 25–30. All setae aciculate and smooth.
Peritreme and peritrematic plates. Peritreme about as wide as stigma, extending forward almost to level of j 1; anterior half visible from a dorsal view. Peritrematic plate fused with dorsal shield distally anteriad of s 1, extending posteriorly behind coxa IV; with one lyrifissure next to coxae II (pore not distinct because of position) and with two pairs of distinguishable lyrifissures behind stigma, probably fused with posterior end of exopodal shield beside and posteriad of coxa IV.
Spermathecal apparatus. Not distinguishable.
Legs. Lengths: I: 340–362; II: 240–245; III: 220–230; IV: 300–305. Chaetotaxy (legs I–IV): coxae—0 0/1 0/1 0; 0 0/1 0/1 0; 0 0/1 0/1 0; 0 0/1 0/0 0; trochanters—1 0/1 1/2 1; 1 0/1 0/2 1; 1 1/1 0/2 0; 1 1/1 0/2 0; femora—2 3/ 1 2/2 2; 2 3/1 2/2 1; 1 2/1 1/0 1; 1 2/1 1/0 1; genua—2 3/1 3/1 2; 2 3/1 2/1 2; 2 2/1 2/1 1; 2 2/1 3/0 1; tibiae—2 3/1 2/1 2; 2 2/1 2/1 2; 2 1/1 2/1 1; 2 1/1 3/1 2; tarsi II–IV, 18, 18, 18. All legs with pretarsi, including a pair of claws and pulvilli with median section rounded. Legs II–IV with elongate and acuminate paradactyli (Fig. 22). Leg setae aciculate and smooth, without macrosetae.
Adult male (Figs 23–26) (Two specimens measured).
Gnathosoma. Chelicera with antiaxial and dorsal lyrifissures distinct (Fig. 23); fixed cheliceral digit 30 long, with six teeth in addition to apical tooth and a minute setiform pilus dentilis; movable cheliceral digit 28 long with one tooth in addition to apical tooth; spermadactyl 29 long, almost straight; palp chaetotaxy, deutosternal region and position of hypostomal setae as in adult female. Anterior region of epistome with three extensions, each 3–4- tined (Fig. 24). Setae h 1, h 2, h 3 not visible, pc 15 long.
Dorsal idiosoma (Fig. 25). Dorsal shield 267–282 long and 140–155 wide at widest level. Podonotal and opisthonotal shields fused, without lateral incisions at region of fusion. Podonotal region with 23 pairs of setae (j 1– j 6, z 1– z 6, s 1– s 6 and r 2– r 6) and three pairs of distinguishable lyrifissures. Opisthonotal region with 19 pairs of setae (J 1– J 5, Z 1– Z 5, S 1– S 5, R 1– R 4), and nine pairs of distinguishable lyrifissures. Unsclerotised cuticle along lateral margins of opisthonotal region with one pair of setae (R 5). Measurements of setae: j 1 10–11, j 2 13, j 3 11–13, j 4 13–14, j 5 11–12, j 6 11–12, J 1 11–12, J 2 13, J 3 12–13, J 4 13–14, J 5 8–9, z 1 10–11, z 2 11–12, z 3 10–11, z 4 12– 13, z 5 12, z 6 11–12, Z 1 11–12, Z 2 13, Z 3 12, Z 4 12–14, Z 5 17–18, s 1 10, s 2 10, s 3 10, s 4 11, s 5 11, s 6 12, S 1 12 –13, S 2 12–13, S 3 13, S 4 12–14, S 5 13–14, r 2 10, r 3 10, r 4 10, r 5 10, r 6 10, R 1 10–11, R 2 10–12, R 3 10–11, R 4 10–11, R 511–12. Shape of setae as in adult female.
Ventral idiosoma (Fig. 26). Tritosternum broken (seemingly as in female). Pre-sternal platelets as in female. Sternogenital shield smooth 120–125 long at mid-line and 60–65 wide between setae st 1 and st 2, posterior margin slightly concave; with four pairs of setae (st 2 and st 4) and three pairs of lyrifissures (iv 1, iv 2 and iv 5). Ventrianal shield subtriangular, 95 long at mid-line and 105 wide at widest point; with seven pairs of setae (Jv 1– Jv 5, Zv 2 and Zv 3) in addition to circumanal setae and one pair of distinguishable lyrifissures. Post-anal seta longer than paraanal seta, the latter inserted slightly anteriad of level of posterior margin of anal opening. Discrete metapodal plates absent. Measurements of setae: st 1 15, st 2 15–17, st 3 15–17, st 4 16 st 5 16–17, Jv 1 17, Jv 2 16–17, Jv 3 16, Jv 4 9, Jv 5 17–20, Zv 2 15, Zv 3 8, para-anal 18, post-anal 25–26. Shape of setae as in adult female.
Peritreme and peritrematic plates. Peritreme similar to female; peritrematic plate indistinguishable.
Legs. Lengths: I: 277–290; II: 212; III: 1 85–190; IV: 235–240. Chetotaxy and shape of setae and pretarsi as in adult female.
Remarks. Because of the very light sclerotisation of the dorsal shield, it was not possible to be absolutely sure about the insertion of the R setae. The collection of additional specimens in the type locality might be required for a definitive conclusion in this regard. In this publication we provide information not given in the original description of the species, for females and males. In our examination of the holotype and a paratype female we could not confirm the presence of the discrete incisions immediately behind S 1, illustrated in the original description.
description: Published as part of Santos, Jandir C. & De Moraes, Gilberto J., 2016, A new species of Leioseius (Acari: Ascidae) from Brazil, redescription of Leioseius basis and a key for separation of the world species of the genus in Zootaxa 4158 (1), DOI: 10.11646/zootaxa.4158.1.2, http://zenodo.org/record/257043