Gamasellodes lavafesii Castro, Azevedo & Castilho, 2020

De Castro, Matheus C., Barros, Ávyla R. A., De Azevedo, Emiliano B., Britto, Erika P. J., Castilho, Raphael C. & De Moraes, Gilberto J., 2020, A new species of Gamasellodes Athias-Henriot (Mesostigmata: Ascidae) from Brazil and a key to the world species of the genus, Zootaxa 4801 (2), pp. 291-300 : 292-296

Gamasellodes lavafesii Castro, Azevedo & Castilho sp. nov.

Diagnosis. Anterior region of epistome with three pointed, smooth projections of similar lengths; podonotal shield with 16 pairs of setae (s 1 and s 2 on unsclerotised cuticle; in few specimens, s 3 of one side also on unsclerotised cuticle); opisthonotal shield with 15 pairs of setae; unsclerotised cuticle along lateral margins of opisthonotal shield with six pairs of setae (R 1– R 5, UR 3); unsclerotised opisthogastric cuticle with a slender sclerotised line followed by five pairs of setae (Jv 1 and Zv 1– Zv 4) and a pair of tiny transversely elongate platelets; ventrianal shield with four pairs of setae (Jv 2– Jv 5); exopodal plate distinguishable as a pair of aligned elongate structures along coxae II and III, fused distally to area of fusion of dorsal shield and pertirematic plate; peritreme extending anteriorly almost to level of z 1.

Description. Adult female ( Figures 1–12 )—Eight specimens measured.

Gnathosoma. Fixed cheliceral digit 25 (24–28) long, with five teeth in addition to the apical tooth ( Figure 1 ); pilus dentilis aciculate, between second and third tooth; movable cheliceral digit 26 (25–28) long, with two teeth in addition to the apical tooth; arthrodial process of chelicera shaped as a coronet-like fringe; dorsal lyfirissure and dorsal setae distinct; antiaxial lyrifissure undistinguishable. Number of setae on palp trochanter–tarsus: 2–5–6–14– 15, all aciculate and smooth, except al of femur and al 1 and al 2 of genu, stout and blunt; palp tarsal claw 2–tined ( Figure 2 ). Anterior region of epistome with three subequal, smooth projections ( Figure 3 ). Deutosternum with seven roughly transverse rows of 2–4 denticles each and a smooth distal row; rows delimited by lateral lines ( Figure 4 ). Internal malae totally separated from each other, each bifurcate, outer branches fimbriate and inner branches smooth. Corniculus horn-like, about twice as long as its basal width. Seta h 3 about in longitudinal line with h 1 and in transverse line and mesad of h 2. Measurements of setae: h 1 11 (9–13), h 2 9 (8–10), h 3 15 (13–16), sc 13 (13–14); all setae aciculate and smooth.

Idiosoma. Length 312 (298–330), width 180 (157–199). All idiosomatic setae aciculate and smooth, except Z 5, sparsely denticulate.

Dorsal idiosoma ( Figure 5 ). Podonotal shield mostly smooth, except for a punctate band along the posterior margin; with scant marginal lines anteriad of z 2; shield with delineated marginal strip posteriad of z 2; 162 (156–168) long and 128 (119–138) wide; usually with 16 pairs of setae (j 1– j 6, z 1– z 6 and s 3– s 6; s 3 of one side on unsclerotised cuticle in few specimens), four pairs of distinguishable lyrifissures (id 1, id 2, id 5 and id 6) and three pairs of pores (gd 1, gd 2 and gd 5). Unsclerotised cuticle along lateral margins of podonotal shield usually with six pairs of setae (s 1– s 2 and r 2– r 5) and one pair of lyrifissures (is 1); r 1 and r 6 absent. Opisthonotal shield mostly smooth, except for a reticulated region between J 4, J 5 and Z 4 bordered posteriorly by an undulating transverse, arched line; shield with delineated strip along lateral margins, from anterior corner to insertion of S 4; 153 (145–167) long and 129 (121– 139) wide; with 15 pairs of setae (J 1– J 5, Z 1– Z 5 and S 1– S 5), nine pairs of distinguishable lyrifissures (idm 1, idm 2, idm 3, idm 4, idm 6, idl 3, idl 4, idl 5 and idx) and two pairs of pores (gd 8 and gd 9). Unsclerotised cuticle along lateral margins of opisthonotal shield with six pairs of setae ( R 1 – R 5 , UR 3); lyrifissure Rp indistinguishable. Measurements of setae: j 1 14 (13–15), j 2 13 (12–13), j 3 13 (12–15), j 4 13 (12–14), j 5 12 (11–13), j 6 12 (11–13), z 1 8 (8–9), z 2 14 (13–15), z 3 12 (11–13), z 4 14 (13–15), z 5 13 (12–14), z 6 11 (11–12), s 1 11 (11–12), s 2 12 (11–12), s 3 14 (13–14), s 4 14 (13–15), s 5 13 (12–14), s 6 14 (14–16), r 2 12, r 3 14 (14–15), r 4 11 (11–12), r 5 11 (10–12), J 1 11 (10–12), J 2 11, J 3 9 (9–10), J 4 14 (13–15), J 5 9 (9–10), Z 1 13 (12–14), Z 2 14 (13–15), Z 3 18 (16–18), Z 4 22 (21–24), Z 5 38 (33–41), S 1 12 (11–12), S 2 14 (13–15), S 3 15 (14–16), S 4 20 (18–21), S 5 18 (17–19), R 1 10 (9–10), R 2 9 (9–10), R 3 9 (9–10), R 4 9 (8–10), R 5 7 (6–8), UR 3 9 (8–10).

Ventral idiosoma ( Figure 6 ). Base of tritosternum 13 (12–14) long and 9 (9–10) wide proximally ( Figure 7 ); laciniae 40 (38–43) long, separated for about 90% of their total length, pilose. Pre-sternal area weakly sclerotised, represented by two lobes fused with sternal shield, punctate and striate. Sternal shield mostly smooth, with scant faint striae along lateral margins; posterior margin slightly concave; approximately 89 (88–91) long and 75 (72–79) wide; with three pairs of setae and three pairs of lyrifissures (iv 1, iv 2 and iv 3); distances st 1– st 3 70 (69–72), st 2– st 2 42 (42–44). Seta st 4 on unsclerotised cuticle, but very close to posterior margin of sternal shield. Anterior section of endopodal plate fused with sternal shield; section behind sternal shield reduced to a slender, v-shaped platelet between coxae III–IV. Genital shield smooth, posteriorly rounded; bearing st 5; extending posteriorly well behind coxa IV; 76 (75–77) long and 38 (37–39) wide; distance st 5– st 5 34 (32–37). Lyrifissure iv 5 on unsclerotised cuticle, posterolaterad of st 5. Unsclerotised opisthogastric cuticle with a slender sclerotised line followed by five pairs of setae (Jv 1 and Zv 1– Zv 4), a pair of tiny transversely elongate platelets and a pair of lyrifissures (ivo). Ventrianal shield smooth in the anterior half, with rough punctation elsewhere; 90 (84–100) long and 120 (115–130) wide; with four pairs of setae (Jv 2– Jv 5) in addition to circumanals; anal opening small, about 1/6 of shield length; 15 (14–16) long. Cribrum visible as a narrow and elongate band along posterior margin of ventrianal shield. Exopodal plate distinguishable as a pair of aligned elongate structures along coxa II and along coxa III. Two pairs of elongate metapodal plates, the anterior transversely elongate and posterior longitudinally elongate. Pore gv 2 distinct, on unsclerotised cuticle. Measurements of setae: st 1 14 (13–14), st 2 14 (13–15), st 3 13 (12–15), st 4 1 (11–13), st 5 11, Jv 1 14 (12–15), Jv 2 19 (17–21), Jv 3 12 (11–14), Jv 4 13 (11–14), Jv 5 28 (26–31), Zv 1 10 (9–11), Zv 2 13 (12–13), Zv 3 8 (6–9), paraanal 14 (14–15) and post-anal 32 (31–34).

Peritreme and peritrematic plate. Peritreme extending anteriorly almost to level of z 1. Peritrematic plate not fused with exopodal plate and reduced to three sections: between coxae II and III, bearing a lyrifissure (ip 2) and a pore (gp 1), and anteriad of coxa II (both dorsad of peritreme); and between coxae I and II (ventrad of peritreme); anterior end of the plate barely fused with dorsal shield at level of z 1; with two lyrifissures (ip 3 and ip 4) and a pore (gp 2) behind each stigma ( Figure 8 ).

Spermathecal apparatus. Not distinguishable.

Legs ( Figures 9–12 ). Lengths: Leg I: 227 (215–238); Leg II: 183 (178–190); Leg III: 166 (162–176); Leg IV: 214 (200–229). Setation (legs I– IV): coxae: 2, 2, 2, 1; trochanters: 6, 5, 5, 5; femora: 14, 10, 6, 6; genua: 13, 10, 8, 9; tibiae: 13, 10, 8, 10; tarsi: I not counted, 18, 18, 18. Seta ad 2 of tarsus IV 26 (25–28) considerably longer than pd 2 16 (15–17). All legs with pretarsi containing a pair of strongly sclerotised claws; median section of pulvilli of legs I–IV rounded.

Adult male. Not found.

Material examined. Holotype female and three paratype females from soil and litter of a grain production area (soybean and maize rotation) in a transition region between Cerrado and Amazon Rainforest biomes at Sinop (11°50’54” S; 55°22’07”W, 384 m above sea level), Mato Grosso state, Brazil, August 2015 / July 2016, collected by E.P.J. Britto. Four paratypes from soil and litter of an undisturbed area of the Caatinga biome at Olho d’Água das Flores (9°33’38” S; 37°16’08” W, 287 m above sea level), Alagoas state, Brazil, December 2018, collected by A.R.A. Barros. All types deposited at Departamento de Entomologia e Acarologia, Escola Superior de Agricultura “Luiz de Queiroz” ( ESALQ), Universidade de São Paulo ( USP), Piracicaba, State of São Paulo, Brazil.

Etymology. This mite is named for Lasaro Vanderlei Fernandes da Silva (in memorian) for his great professional contribution as a technician of Departamento de Entomologia e Acarologia, Escola Superior de Agricultura “Luiz de Queiroz” (ESALQ), Universidade de São Paulo (USP), Piracicaba, São Paulo state, Brazil.

Remarks. Gamasellodes lavafesii Castro, Azevedo & Castilho sp. nov. is most similar to Gamasellodes magniventris Mineiro, Lindquist & Moraes, 2009 , but females of the latter have posterior margin of genital shield truncate; ventrianal shield broader, incorporating the pair of platelets between genital and ventrianal shields, with anterior margin nearly straight and less densely punctate; setae Jv 1, Zv 1 and Zv 2 in nearly transverse alignment; with a single pair of ellipsoidal metapodal platelets; and Jv 3 in about transverse line with Jv 2. The new species also differs from the similar Gamasellodes novibicolor Ma, 2005 by the different ornamentation of the dorsal idiosomal shield and by having setae r 4 and r 5, and from Gamasellodes plaire Halliday, Walter & Linsquist, 1998 by the different ornamentation of the dorsal idiosomal shields and the straight posterior margin of the genital shield and anterior margin of the ventrianal shield in the latter.

The marginal strip on the dorsal shield of the new species here described is also depicted in the descriptions of some species of Gamasellodes ( Moraes et al. 2016) , namely Gamasellodes andinus Rueda-Ramirez, Varela & Moraes, 2016 ; Gamasellodes insignis ( Hirschmann, 1962) ; Gamasellodes rectiventris Lindquist, 1971 and Gamasellodes vermivorax Walter, 1987 . Differences between these and the new species are mentioned in the key to the separation of the species of the genus.

The type localities of this species are quite distant from each other, about 2,000 km in straight line. These places are quite similar in relation to temperature (annual average of about 25ºC in Sinop and Olho d´Água das Flores), but quite different in relation to rainfall (annual total average of respectively about 2,550 and 640 mm) .

Figures

FIGURES 1–4. Gamasellodes lavafesii Castro, Azevedo & Castilho sp. nov. Adult female. 1. Lateral (antiaxial) view of chelicera; 2. Apotele; 3. Epistome; 4. Hypostome.

FIGURES 5–8. Gamasellodes lavafesii Castro, Azevedo & Castilho sp. nov. Adult female. 5. Dorsal idiosoma; 6. Ventral idiosoma; 7. Tritosternum; 8. Peritrema and peritrematic plate. Lyrifissures and pores enlarged for improved visibility.

FIGURES 9–12. Gamasellodes lavafesii Castro, Azevedo & Castilho sp. nov. Adult female. 9. Leg I, coxa-tibia, dorsal view; 10. Legs II, dorsal view; 11. Legs III, dorsal view; 12. Legs IV, dorsal view.