Protogamasellus pantanal, Yamada & De Moraes, 2020

Yamada, Mariana & De Moraes, Gilberto J., 2020, A key to the species of Protogamasellus (Acari: Ascidae), with a new species from the Brazilian Pantanal, Zootaxa 4801 (2), pp. 343-354 : 347-349

Protogamasellus pantanal n.sp.

( Figs 1–6 )

Diagnosis. Fixed cheliceral digit with 11–13 teeth and movable digit with three teeth. Epistome anteriorly rounded, with serrate margin. Podonotal shield with a continuous transverse line slightly posterior to z 6 and with 16 pairs of setae, setae j 2 inserted almost in a transverse line with the insertions of j 1 and z 1; unsclerotised cuticle next to podonotal shield with six pairs of setae (s 1, s 2, r 2– r 5); with a pair of accessory plates anterolaterad of podonotal shield; opisthonotal shield with punctate depressions distributed, a continuous transverse line at the level of J 1 and 15 pairs of setae; with a pair of short transverse lines next to Z 1– S 1 and wavy lines between Z 3 and Z 5; unsclerotised cuticle next to opisthonotal shield with seven pairs of setae (R 1– R 6 and UR); ventrianal shield with two pairs of setae in addition to circumanals (Jv 1, Jv 4, Jv 5 and Zv 1 on unsclerotised cuticle); peritreme short, extending anteriorly almost to the level of r 3.

Adult female ( Figs 1–6 ) Thirteen specimens measured.

Gnathosoma. Chelicera with antiaxial and dorsal poroids, and dorsal setae distinct; fixed cheliceral digit 27 (25–28) long, with 11–13 teeth and setiform pilus dentilis; movable digit 26 (26–27) long, with three teeth ( Fig. 1 ). Epistome anteriorly rounded, with serrate margin (about 12 denticles) ( Fig. 2 ). Deutosternum with a smooth transverse line followed by six denticulate transverse lines, each with 6–8 denticles ( Fig. 3 ); corniculi spine-like, subparallel to each other. Seta h 3 in longitudinal line with h 1 and posteriad of h 2. Setal measurements: h 1 8 (7–9), h 2 5 (3–6), h 3 11 (10–14), pc 8 (7–10); setae aciculate and smooth.

Dorsal idiosoma ( Fig 4 ). Idiosoma 270 (257–280) long and 129 (125–133) wide at level of r 3. Podonotal shield smooth, except for a continuous transverse line slightly posterior to z 6; 124 (118–128) long and 105 (103–107) wide at level of s 3; with 16 pairs of setae, four pairs of poroids and a pair of solenostomes; setae j 2 inserted almost in transverse line with j 1 and z 1. Unsclerotised cuticle next to the podonotal shield with six pairs of setae (s 1, s 2, r 2– r 5). With a pair of accessory sclerites fitting the anterolateral depressions of podonotal shield, between r 2 and z 1. Opisthonotal shield with a continuous transverse line at level of J 1, a pair of short transverse lines next to Z 1– S 1 and wavy lines between Z 3 and Z 5; with a series of punctate depressions distributed in the opisthonotal shield; 134 (128–140) long and 91 (89–94) wide at the level of S 3; with 15 pairs of setae, seven pairs of poroids and three pairs of solenostomes; solenostome between Z 3 and Z 4 large, solenostome between Z 2 and S 3 smaller, and solenostome close to S 5 inserted on a large sclerite. Unsclerotised cuticle next to the opisthonotal shield with seven pairs of setae ( R 1 – R 6 , UR); distinct Rp poroid between R 3 and R 4 . Setal measurements: j 1 24 (22–26), j 2 16 (14–17), j 3 21 (20–23), j 4 20 (16–23), j 5 18 (15–20), j 6 17 (16–19), J 1 26 (23–29), J 2 28 (23–30), J 3 31 (28–33), J 4 32 (30–35), J 5 16 (13–17), z 1 13 (9–16), z 2 20 (18–21), z 3 21 (15–24), z 4 23 (22–25), z 5 22 (21–24), z 6 23 (21–24), Z 1 24 (23–25), Z 2 26 (24–27), Z 3 26 (23–28), Z 4 29 (26–32), Z 5 35 (30–38), s 1 17 (14–23), s 2 14 (12–16), s 3 23 (20–24), s 4 23 (21–24), s 5 23 (21–24), s 6 22 (21–23), S 1 22 (21–24), S 2 23 (20–25), S 3 25 (22–26), S 4 26 (24–28), S 5 22 (20–23), r 2 21 (20–24), r 3 19 (11–21), r 4 12 (10–16), r 5 11 (9–12), R 1 11 (9–13), R 2 11 (10–14), R 3 12 (10–15), R 4 13 (11–16), R 5 16 (11–17), R 6 21 (17–24), UR 7 (9–5); setae aciculate and smooth.

Ventral idiosoma ( Fig. 5 ). Base of tritosternum 14 (13–16) long and 7 (6–9) wide proximally; laciniae 40 (38–42), separated for about 75% of their total length, pilose. Pre-sternal area slightly sclerotised, punctate and with scant, almost indistinguishable diagonal lines. Sternal shield smooth; anterior margin deeply emarginated, posterior margin concave; with a transverse bend anteriad of iv 1 less sclerotised than elsewhere; 72 (70–74) long and 65 (60–68) wide at the middle of coxae II; with three pairs of setae and three pairs of poroids; distances st 1– st 3 56 (55–59), st 2– st 2 43 (40–45). Metaesternal plates indistinguishable, fourth pair of sternal setae (st 4) on unsclerotised cuticle. Genital shield bearing st 5; with a transverse line behind st 5 delimiting a more sclerotised posterior region; 52 (45–57) long and 28 (26–29) wide at widest level; distance st 5– st 5 24 (22–25); poroid iv 5 on unsclerotised cuticle, posterolaterad of st 5. With two pairs of metapodal plates, the anterior rounded and the posterior ellipsoidal. Unsclerotised opisthogastric cuticle with a sclerotised transverse line followed by three platelets between genital and ventrianal shield; with four pairs of setae (Jv 1, Jv 4, Jv 5 and Zv 1), one pair of solenostomes and two pairs of poroids. Ventrianal shield with sparse lines, with anterior margin arched; 81 (75–90) long and 96 (90–100) wide at level of Jv 4; with two pairs of setae (Jv 2– Jv 3) in addition to circumanals; para-anal seta inserted just anteriad of anterior margin of anal opening; post-anal setae outside the shield; with small anal opening, 15 (14–17) long. Anterior region of the endopodal plate fused with sternal shield; posterior region elongate, between coxae III and IV. Exopodal plate reduced to two subtriangular platelets between coxae II–III and III–IV. Setal measurements: st 1 16 (14–18), st 2 15 (13–16), st 3 16 (15–18), st 4 13 (12–14), st 5 10 (9–13), Jv 1 12 (10–13), Jv 2 15 (14–17), Jv 3 16 (14–19), Jv 4 8 (7–10), Jv 5 26 (24–30), Zv 1 10 (7–15), para-anal 20 (17–22), post-anal 36 (35–40); setae aciculate and smooth.

Peritreme and peritrematic plate. Peritreme short, extending anteriorly almost to the level of r 3; peritrematic plate virtually indistinguishable anteriad of stigma; behind each stigma, peritrematic plate continuing as a narrow strip with two poroids and a solenostome.

Spermathecal apparatus. Indistinct.

Legs. Lengths of legs (not including pretarsus): I: 253 (240–260); II: 174 (170–180); III: 156 (150–165); IV: 218 (210–230). Setation (legs I IV): coxae: 2 2 2 1; trochanters: 1 0/1 1/2 1; 1 0/1 0/2 1; 1 0/1 0/2 1; 1 0/1 0/2 1; 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 3/2 3/1 2; 2 3/1 2/1 2; 2 2/1 2/0 1; 2 2/1 3/0 0; tibiae: 2 3/2 3/1 2; 2 2/1 2/1 2; 2 1/1 2/1 1; 2 1/1 3/1 1; tarsi: I not counted 18 18 18. All legs with pretarsus containing claws and pulvillus.

Adult male. Not found.

Material examined. Holotype female from pasture soil, June 12, 2019 ; four paratype females from soil of natural vegetation of the Pantanal , September 12, 2018 ; one paratype female from soil of natural vegetation, March 12, 2019 ; two paratype females from soil of corn field, March 12, 2019 ; one paratype female from soil of corn field, June 12, 2019 ; four paratype females from soil of sorghum field, June 12, 2019 .

Etymology. The specific name pantanal refers to the biome from which the type specimens were collected.

Remarks. This species is most similar to Protogamasellus massula ( Athias-Henriot, 1961) , described from Algeria, which also has long opisthonotal setae, a pair of UR setae, podonotal shield with setae j 2 about in transverse line with j 1 and z 1, and with interconnected wavy lines between Z 3 and Z 5. However, P. massula has: ventrianal shield longer than wide; at least J 4, Z 4, Z 5 and S 5 slightly serrate; two anteriormost opisthogastric setae of each side about in longitudinal line; distinct ornamentation of posterior section of opisthonotal shield (U-shaped line around J 4 connected at the base of each side to a diagonal line that reaches base of Z 4) and ventrianal shield (three lines parallel to margins anteriad of J 5 and other lines around anus). Differences between the new species here described and other species of Protogamasellus species can be seen in the dichotomous key subsequently provided in this publication.

Figures

FIGURES 1–6. Protogamasellus pantanal n.sp. Female. 1. Chelicera; 2. Epistome; 3. Hypostome; 4. Tritosternum; 5. Dorsal view of idiosoma; 6. Ventral view of idiosoma.