Rykellus mineiroi, Santos, Jandir C., Castilho, Raphael C., Silva, Edmilson S. & De Moraes, Gilberto J., 2015

Santos, Jandir C., Castilho, Raphael C., Silva, Edmilson S. & De Moraes, Gilberto J., 2015, Two new species of Rykellus (Acari: Mesostigmata: Ologamasidae) from Brazil and a key to the world species of the genus, Zootaxa 3926 (1), pp. 111-121 : 116-119

Rykellus mineiroi n. sp.

Material examined. From litter of a disturbed natural vegetation at ESALQ-USP (22°42’30’’S; 47°38’30’’W), Piracicaba, State of São Paulo: holotype female, one paratype female and one paratype male, 5 April 1999; one paratype female, 21 December 1998; three paratype females, 4 January 1999; two paratype females and two paratype males, 2 July 1999. From litter at base of E. edulis at margin of road between Piracicaba and Anhembi, State of São Paulo: one paratype female, 11 November 2000. All types collected by J.L.C. Mineiro. Holotype female, five paratypes females and two paratypes males 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; two paratypes females and one paratype male deposited at Departamento de Fitossanidade, Faculdade de Ciências Agrárias e Veterinárias ( FCAV), Universidade Estadual Paulista ( UNESP), Jaboticabal, State of São Paulo, Brazil.

Adult female ( Figs 12–19 ) (Five specimens measured). All setae aciculate and smooth.

Gnathosoma. Fixed cheliceral digit 65 (62–68) long, with six teeth in addition to apical tooth and a setiform pilus dentilis ( Fig. 12 ); movable cheliceral digit 63 (61–65) long, with three teeth in addition to apical tooth; dorsal lyrifissure and dorsal seta distinct, antiaxial lyrifissure not visible. Arthrodial process of chelicera shaped as a short coronet-like fringe. Number of setae on palp: (trochanter to tarsus) 2-5-6-14 -15; apotele 3-tined ( Fig. 13 ); setae al 1 and al 2 of palp genu spatulate and smooth ( Fig. 14 ); other palp setae aciculate and smooth. Epistome with an anteromedian extension wider basally and rounded distally, flanked by shorter shoulders, subdivided to varying degrees ( Fig. 15 ). Deutosternal denticles in eight transverse rows contained by the deutosternal lateral lines, which are parallel to each other along the six distal rows of denticles and divergent posteriorly; each row with 5 (most anterior row) to 14 (most posterior row) denticles; first, fourth and seventh rows continuing as smooth lines outside of lateral lines ( Fig. 16 ). Internal malae separated from each other; external margin fimbriate. Seta h 3 about in longitudinal line with h 1, mesad of and slightly posterior to h 2. Measurements of setae: h 1 28 (26–30), h 2 29 (29–30), h 3 27 (25–30), sc 27 (25–29).

Dorsal idiosoma ( Fig. 17 ). Idiosoma 467 (460–475) long and 357 (350–365) wide at widest point. Podonotal and opisthonotal shields fused, completely covering idiosoma and extending to its ventrolateral region, smooth; line of fusion v-shaped. Podonotal region with 22 pairs of setae (s 1 and r 1 absent) and one pair of distinguishable lyrifissure and three pairs of pores. Unsclerotised integument along lateral margins of podonotal region without setae (visible in the ventrolateral regions). Opisthonotal region with 19 pairs of setae and five pairs of distinguishable lyrifissures and five pairs of pores. Unsclerotised integument along lateral margins of opisthonotal region with two pairs of setae (R 1 and R 2) (visible in the ventrolateral regions). Measurements of setae: j 1 15 (12–17), j 2 32 (30–34), j 3 36 (34–38), j 4 33 (32–35), j 5 24 (20–27), j 6 27 (25–28), z 1 11 (10–12), z 2 31 (29–33), z 3 41 (40–41), z 4 40 (38–42), z 5 27 (25–30), z 6 29 (28–31), s 2 25 (24–26), s 3 25 (23–26), s 4 34 (33–36), s 5 33 (31–35), s 6 33 (32–35), r 2 14 (13–15), r 3 11 (10–12), r 4 11 (10–12), r 5 12 (10–13), r 6 26 (24–28), J 1 30 (30–31), J 2 28 (27–30), J 3 33 (32–35), J 4 33 (31–35), J 5 24 (22–26), Z 1 32 (31–33), Z 2 28 (25–32), Z 3 31 (30–32), Z 4 30 (28–32), Z 5 30 (28–31), S 1 25 (23–28), S 2 27 (25–30), S 3 26 (22–30), S 4 22 (21–24), S 5 32 (30–34), R 1 9 (9–10), R 2 9 (8–10), R 3 21 (20–22), R 4 23 (21–25), R5 26 (25–27), UR 4 27 (23–31).

Ventral idiosoma ( Fig. 18 ). Base of tritosternum 10 (9–10) long and 21 (20–22) wide proximally ( Fig. 19 ); laciniae 104 (103–104), separated for about 60% of their total length, pilose. A pair of presternal plates present, each with a transverse line. Sternal shield smooth; 126 (123–129) long at mid-line and 87 (85–90) wide between coxae II and III; with four pairs of setae and three pairs of lyrifissures; with a triangular process laterad of lyrifissure iv 1; posterior margin concave, not fused with section of endopodal plate behind middle of coxae III. Genital shield smooth; extending posteriorly slightly behind coxa IV; posterior margin slightly concave; distance between st 5– st 5 78 (77–80). Genital lyrifissures distinct, placed between genital and ventrianal shields. A pair of elliptical platelets present, each with a transverse line, posterior to coxa IV, perhaps remnant of posterior end of endopodal or exopodal plate (more mesad than usual for metapodal platelets of other Rhodacaroidea). Ventrianal shield almost totally smooth, except for weak striae along anterior margin; 246 (240–252) long at mid-line and 200 (195–205) wide at widest level; with six pairs of setae (Jv 1– Jv 3, Jv 5, Zv 1 and Zv 2) in addition to circum-anal setae and one pair of distinguishable lyrifissure and two pairs of pores; para-anal seta about 1.1 times as long as post-anal seta and inserted between anterior margin and mid-length of anal opening. Unsclerotised integument along margins of ventrianal shield with a pair of setae (Zv 3). Peritreme extending anteriorly to level of region between coxae I and II. Peritrematic shield fused antero laterally to dorsal shield, expanded near coxa IV; with a pair of lyrifissures dorsal of peritreme and at median level of coxa II and a pair posterior to stigma. Exopodal shield distinct from region between coxae I–II to median level of coxa IV, but interrupted at median level of coxa III, forming an anterior elongate plate and a posterior triangular plate. Measurements of setae: st 1 28 (26–30), st 2 23 (22–24), st 3 20 (20–21), st 4 24 (23–25), st 5 25 (23–26), Jv 1 22 (21–22), Jv 2 23 (21–24), Jv 3 24 (23–25), Jv 5 22 (22–23), Zv 1 25 (25–26), Zv 2 25 (24–26), Zv 3 23 (21–25), para–anal 22 (20–24), post-anal 20 (19–22).

Spermathecal apparatus. Not distinguishable.

Legs. Lengths: I: 425 (415–435); II: 315 (305–325); III: 265 (255–274); IV: 341 (328–355). Numbers of setae on legs I–IV: coxae: 2, 2, 2, 1; trochanters: 6, 5, 5, 5; femora: 13, 11, 6, 6; genua: 13, 11, 9, 9; tibiae: 14, 10, 8, 10; tarsi II–IV: 18, 18, 17. Pretarsi I–IV similar in shape, with an elongate ambulacral stalk, a pair of strong claws and three rounded pulvillar lobes; pretarsus I about half as long as other pretarsi.

Adult male ( Figs 20–22 ) (three specimens measured). Shape of setae as in adult female, except for two spurlike ventral setae on femur II and one spur-like ventral seta on each of genu and tibia II.

Gnathosoma. Fixed cheliceral digit 53 (52–55) long, with six teeth in addition to apical tooth and a setiform pilus dentilis ( Fig. 20 ); movable cheliceral digit 55 (52–58) long, with one tooth in addition to apical tooth; spermatodactyl 33 (32–35) long, uniformly arched; dorsal lyrifissure and dorsal seta distinct, antiaxial lyrifissure not visible. Arthrodial process of chelicera, palp chaetotaxy, apotele, epistome, deutosternum and position of hypostomal setae as in adult female. Measurements of setae: h 1 28 (27–29), h 2 24 (23–25), h 3 26 (25–28), sc 24 (23–25).

Dorsal idiosoma. Idiosoma 420 (415–425) long and 345 (340–350) wide at widest point; dorsal shield similar to that of adult female. Measurements of setae: j 1 9 (8–10), j 2 36 (34–38), j 3 28 (27–30), j 4 32 (28–35), j 5 25 (23–27), j 6 25 (24–25), z 1 9 (8–10), z 2 29 (29–30), z 3 33 (32–35), z 4 37 (35–40), z 5 30 (29–30), z 6 29 (29–30), s 2 19 (16–23), s 3 25 (24–27), s 4 33 (30–36), s 5 32 (30–35), s 6 33 (31–35), r 2 14 (13–14), r 3 12 (12–13), r 4 12 (11–13), r 5 11 (11–12), r 6 28 (27–29), J 1 31 (28–34), J 2 30 (30–31), J 3 27 (26–28), J 4 31 (27–35), J 5 27 (25–29), Z 1 33 (31–35), Z 2 33 (31–34), Z 3 32 (31–33), Z 4 26 (23–30), Z 5 30 (27–34), S 1 26 (25–28), S 2 32 (30–33), S 3 29 (28–30), S 4 30 (30–31), S 5 25 (25–26), R 1 10 (10–11), R 2 9 (9–10), R 3 27 (26–29), R 4 25 (25–26), R 5 31 (29–33), UR 4 26 (25–27).

Ventral idiosoma ( Fig. 21 ). Base of tritosternum 15 (15–16) long and 22 (21–22) wide proximally; laciniae 70 (69–70), other characteristics as in adult female. With a pair of presternal plates, each with a transverse line. Sternogenital shield smooth, 124 (123–125) long and 117 (114–120) wide between coxae II and III; with five pairs of setae and three pairs of lyrifissures; posterior margin concave. Ventrianal shield with transverse striae connected by weak diagonal lines along anterior margin, 222 (220–225) long at mid-line and 185 (175–195) wide at widest point; with six pairs of setae (Jv 1– Jv 3, Jv 5, Zv 1 and Zv 2) in addition to circum-anal setae and three pairs of distinguishable lyrifissures; para-anal seta about 1.1 times as long as post-anal seta and inserted about in line with anterior margin of anal opening. Unsclerotised integument along margins of ventrianal shield with a pair of setae (Zv 3). Peritreme, peritrematic and exopodal shields as in adult female. Measurements of setae: st 1 23 (21–25), st 2 25 (23–28), st 3 22 (20–23), st 4 25 (21–29), st 5 21 (20–23), Jv 1 20 (20–21), Jv 2 22 (21–22), Jv 3 21 (21–22), Jv 5 23 (21–24), Zv 1 24 (23–26), Zv 2 22 (20–23), Zv 3 21 (20–22), para-anal 21 (21–22), post-anal 19 (17–22).

Legs. Lengths: I: 425 (415–435); II: 315 (305–325); III: 264 (255–274); IV: 341 (328–355). Numbers of setae of leg segments similar to those of adult female. With two ventral spur-like structures on femur II (occupying same position as setae av 1 and av 2 of female) and one ventral spur-like structure on each of genu and tibia II (occupying respectively same position as setae av 2 of female) ( Fig. 22 ). All legs with pretarsi similar to those of adult female.

Etymology. The name mineiroi is used in honour of Jeferson Luiz de Carvalho Mineiro of Instituto Biológico, Campinas, State of São Paulo, Brazil, collector of the type specimens of this species.

Remarks. Rykellus mineiroi n. sp. is most similar to Rykellus anibali n. sp., but females of the latter have anterolateral extensions of epistome rounded distally; there is a platelet between the paired presternal plates; and the reticulation of the region next to the anterior margin of the ventrianal shield more extensive, reaching the anterolateral corners. In addition, in males of R. anibali Zv 3 is inserted on the ventrianal shield. The following characteristics distinguish other Rykellus species from Rykellus mineiroi : epistome without extensions laterad of stout spines laterad of anteromedian extension; sternal shield fused with section of endopodal plate near coxa IV; and peritrematic, exopodal and metapodal shields fused in R. darglensis and R. nkandhlaensis . Podonotal and opisthonotal regions with 19–20 and 16–17 pairs of setae respectively in R. brevipellitus and R. ovalis . Setae J 2, J 3 and J 4 at least as long as distance between their bases and bases of respective subsequent setae of J series in R. ubatubaensis and R. longopilus .

Figures

FIGURES 12 – 19. Rykellus mineiroi sp. n. Female. 12. Antiaxial view of chelicera; 13. Apotele; 14. Palp genu; 15. Epistome; 16. Hypostome; 17. Dorsal idiosoma; 18. Ventral idiosoma; 19. Tritosternum. Lyrifissures and pores enlarged for improved visibility.

FIGURES 20 – 22. Rykellus mineiroi sp. n. Male. 20. Antiaxial view of chelicera; 21. Ventral idiosoma; 22. Anterolateral view of femur, genu and tibia of leg II. Lyrifissures and pores enlarged for improved visibility.