Lasioseius siamensis Silva and Moraes, 2013

da Silva, Renan V., Narita, João Paulo Z., Vichitbandha, Patchanee, Chandrapatya, Angsumarn, Konvipasruang, Ploychompoo, Kongchuensin, Manita & de Moraes, Gilberto J., 2013, Prospection for predatory mites to control coconut pest mites in Thailand, with taxonomic descriptions of collected Mesostigmata (Acari), Journal of Natural History (J. Nat. Hist.) 48 (11 - 12), pp. 699-719 : 705-710

Lasioseius siamensis Silva and Moraes , sp. nov.

Adult female (three specimens measured) ( Figure 1 )

Diagnosis

Adults: Fixed and movable cheliceral digits with about 14 and with four teeth, respectively. Anterior margin of epistome without extensions, convex, with 14–16 denticles in the median region. Seta sc much longer than h1, in turn longer than the subequal h2 and h3. Deutosternal denticles in seven rows. Dorsal shield scantly reticulate, with 16 and 15 pairs of setae on podonotal and opisthonotal regions; with two pairs of setae on unsclerotized cuticle along margins of dorsal shield. Most of J, Z and S setae not reaching the insertion of the next seta in the respective series. All dorsal idiosomal setae ridged and, except for J5, r5 and R1 with distinct lateral barbed flat expansions mostly visible in distal half (usually referred to as tricarinate); J5 with few basal barbs; r5 and r1 smooth. Platelets between genital and ventrianal shield absent. With nine pairs of opisthogastric setae, four of which on ventrianal shield; the latter with a pair of small marginal pores about in transverse line with Jv4. Tibia I with 13 setae.

Gnathosoma ( Figure 1A–C ). Cheliceral shaft length (from base of first segment to apex of fixed cheliceral digit) 91 (85–100) long; dorsal and lateral lyrifissures as well as dorsal seta distinct (the latter stout, slightly paraxial and somewhat appressed to surface of fixed digit, not easily discernable under phase contrast). Fixed digit 31 (30– 33) long, with aciculate pilus dentilis and about 14 teeth, including offset subapical tooth, in addition to apical tooth; movable cheliceral digit 41 (36–47) long, with four teeth in addition to apical tooth. Anterior margin of epistome without extensions, convex and with 14–16 denticles in the median region; apex at level slightly anterior to base of palp trochanter. Corniculi tapered, well separated and subparallel to each other. Deutosternum relatively wide 7.5 (7–8); deutosternal denticles in seven rows; the first five of uniform lengths, delimited by lateral lines, with two to four denticles each; sixth row with 10–18 denticles divided in two separate groups that extend beyond lateral lines; seventh row with four denticles. Palpus 172 (145–200) long; numbers of setae from trochanter to tibia: 2, 5, 6, 14; apotele two-tined. Hypostomal and palp-coxal setae aciculate: h1 31 (27–37), h2 21 (20–22), h3 23 (15–30) and sc 35 (30–39).

Dorsum of idiosoma ( Figure 1D ). Holodorsal shield 401 (347–460) long and 207 (185–245) wide at level slightly posterior to r3; with distinct reticulation between J1 and Z4 and with irregular and scantly reticulation elsewhere. Podonotal region of dorsal shield with 16 pairs of setae (j1–j6, z2–z6, s3–s6, r3), five pairs of lyrifissures and two pairs of pores. Opisthonotal region of dorsal shield with 15 pairs of setae (J1–J5, Z1–Z5, S1–S5), 11 pairs of lyrifissures and two pairs of pores. Lateral unsclerotized cuticle with two pairs of marginal setae (r5 and R1 ), a pair of lyrifissures and no pores. Lengths of dorsal setae: j1 28 (25–35), j2 17 (13–23), j3 28 (25–33), j4 21 (19–25), j5 21 (20–24), j6 22 (20–24), J1 21 (20–24), J2 22 (20–25), J3 22 (20–25), J4 22 (20–25), J5 12 (10–15), z2 23 (21–26), z3 23 (21–28), z4 23 (21–27), z5 21 (19– 24), z6 21 (19–25), Z1 23 (20–27), Z2 22 (20–26), Z3 28 (25–32), Z4 44 (43–45), Z5 65, s3 24 (23–25), s4 28 (27–30), s5 25 (23–27), s6 28 (27- 30), S1 24 (20–29), S2 26 (23–32), S3 29 (25–37), S4 35 (29–44), S5 37 (31–50), r3 37 (30–47), r5 19 (16–25), R1 17 (15–20). Most of J, Z and S setae not reaching the insertion of the next seta in the respective series. All dorsal idiosomal setae ridged and, except for J5, r5 and R1 with distinct lateral barbed flat expansions mostly visible in distal half (usually referred to as tricarinate); J5 with few basal barbs; r5 and r1 smooth.

Venter of idiosoma ( Figure 1E ). Setae aciculate and smooth, except Jv5 ridged, stout and barbed, and post-anal seta, stout and barbed. Base of tritosternum 13 (12–15) long and 12 (10–13) wide at its median length; laciniae fused for about 60% of their total length [74 (87–58)]. Sternal shield smooth, lineate along lateral margins, bearing setae st1–st3, and two pairs of lyrifissures. Metasternal plate rounded, bearing st4 and a pair of lyrifissures. Genital shield 113 (112–115) long, including hyaline anterior flap, lateral margins moderately concave such that narrowest width between coxae IV [50 (45–55)] about 0.7 its posterior width [72 (70–75)]; truncate posteriorly, smooth, bearing genital seta (st5); paragenital lyrifissure on unsclerotized cuticle posterolaterad of genital seta. Platelets between genital and ventrianal shields absent. Two pairs of metapodal plates, the anterior elongate and smaller than the posterior, which is oval to subtriangular. Ventrianal shield subtriangular, transversely reticulate with few diagonal connections between striae laterally, about as long [134 (122–152)] as wide [137 (125–155)], with four pairs of opisthogastric setae (Jv1–Jv3, Zv2) in addition to circumanal setae and with a pair of minute pores positioned on the margin of the shield, about in transverse line with insertion of Jv4; postanal seta about 1.5 times as long as para-anal seta, anal opening not enlarged, its length (24–30 including frame) about 0.2 the length of ventrianal shield. Unsclerotized cuticle around ventrianal shield with five pairs of opisthogastric setae (Jv4, Jv5, Zv1, Zv3 and Zv5) and three pairs of lyrifissures. Lengths of ventral setae: st1 34 (30– 42), st2 29 (28–32), st3 27 (26–28), st4 25 (20–30), st5 25 (20–32), Jv1 15 (13–18), Jv2 16 (14–28), Jv3 16 (15–17), Jv4 16 (14–18), Jv5 35 (30–40), Zv116 (13–19), Zv2 15 (13–18), Zv3 12 (10–16), Zv5 19 (18–20), para-anal 20, post-anal 30. Endopodal plate distinct between coxae III and IV. Exopodal plate distinct, running from posterior margin of coxa IV to region between coxae I and II.

Peritreme and peritrematic shield. Peritreme extending anteriorly to region between j1; peritrematic shield fused to dorsal shield at level between s3 and s4 and to exopodal shield at level of coxa IV.

Spermatheca ( Figure 1F ). Major duct inflated in a pouch immediately after solenostome, follows as a narrow duct that flares towards a pronounced curve and then as a complex section that apparently corresponds to the vesicle, which is viewed as a variously shaped structure according to position in mounted specimens, seemingly with side projections and with a needle-like blind-ended structure.

Legs ( Figure 1G–I ). Pretarsi of legs I–IV consisting of elongate stalk, a pair of claws and pulvillus with three rounded lobes. Leg I shorter than, and leg IV about as long as, dorsal shield; lengths of legs: I, 356 (332–400); II, 313 (275–370); III, 280 (245– 350); IV, 385 (320–475). All setae aciculate. Chaetotaxy of legs I–IV: coxa 2, 2, 2, 1; trochanter 6 (1-0/1, 1/2-1), 5 (1-0/1, 0/2-1), 5 (1-1/1, 0/2-0), 5 (1-1/1, 0/2-0); femur 12 (2-2/1, 2/3-2), 11 (2-3/2, 2/1-1), 6 (1-2/1, 1/0-1), 6 (1-2/1, 2/0-0); genu 12 (2-3/1, 3/1-2), 10 (2-3/1, 2/0-2), 7 (2-2/0, 2/0-1), 9 (2-2/1, 3/0-1); tibia 13 (2-3/2, 3/1-2), 10 (2-1/1, 3/1-2), 8 (1-2/1, 2/1-1), 10 (2-1/1, 3/1-2); tarsus II–IV 18, 18, 18.

Adult male (one specimen measured) ( Figure 2 )

Gnathosoma ( Figure 2A, B ). Lyrifissures, dorsal seta and pilus dentilis of cheliceral shaft as in adult female; fixed cheliceral digit 19 long, and seven or eight teeth, including offset subapical tooth, in addition to apical tooth; movable cheliceral digit 23 long, with apparently one tooth in addition to apical tooth. Spermatodactyl 32 long, sinuate, tapering distally, with a small subapical heel. Anterior margin of epistome without extensions, denticulate as in adult female. Corniculi tapered, well separated and subparallel to each other. Deutosternum relatively wide, 4 (4–5); deutosternal denticles in seven rows; number of denticles in the first five rows not possible to determine; sixth row with 8–12 denticles; seventh row with four denticles. Hypostomal and palp-coxal setae aciculate: h1 23, h2 16, h3 18 and sc 25.

Dorsum of idiosoma ( Figure 2C ). Holodorsal shield 290 long and 172 wide at level of r3; with distinct reticulation on opisthonotal region of the shield and with irregular and scant reticulation elsewhere. Podonotal region of dorsal shield with 17 pairs of setae (j1–j6, z2–z6, s3–s6, r3, r5), four pairs of lyrifissures and two pairs of gland pores. Opisthonotal region with 16 pairs of setae (J1–J5, Z1–Z5, S1–S5, R1 ), eight pairs of lyrifissures and one pair of pores. Form and relative lengths of dorsal shield setae as in adult female. Unsclerotized cuticle laterad of dorsal shield without setae but with a pair of lyrifissures. Lengths of dorsal setae: j1 20, j2 13, j3 22, j4 16, j5 16, j6 17, J1 16, J2 17, J3 17, J4 15, J5 9, z2 16, z316, z417, z5 15, z6 16, Z1 17, Z2 18, Z3 23, Z4 38, Z5 45, s3 16, s4 19, s5 20, s6 20, S1 18, S2 20, S3 20, S4 20, S5 21, r3 29, r5 14, R1 10. Shape and relative length of dorsal idiosomal setae as in adult female.

Venter of idiosoma ( Figure 2D ). Base of tritosternum 10 long and 10 wide at its median length; laciniae fused for about 50% of their total length (45). Sternogenital shield 127 long and 63 wide at level of st 2, smooth, lineate along lateral margins, bearing st1–st5 and three pairs of lyrifissures. Ventrianal shield subtriangular, transversely striate with few diagonal connections between striae laterally, 130 long, 162 wide at anterolateral corners, covering most of opisthogaster, not fused with peritremal and sternogenital shields, bearing (Jv1–Jv3, Zv1–Zv3) in addition to circumanal setae, five pairs of lyrifissures and a pair of pores next to the margin of the shield, about in transverse line with Zv5. Postanal seta about 1.2 times as long as para-anal seta. Unsclerotized cuticle around ventrianal shield with two pairs of opisthogastric setae (Jv5, Zv5) and a pair of lyrifissures. Lengths of ventral setae: st1 25, st2 22, st3 20, st4 15, st5 16, Jv1 15, Jv2 12, Jv3 13, Jv5 16, Zv1 15, Zv2 12, Zv3 10, Zv5 10, para-anal 17, post-anal 20. Setae aciculate and smooth, except post-anal seta, barbed. Exopodal plates as in adult female.

Peritreme and peritrematic shield. Peritremal shield fused to dorsal shield at level of r3 and to exopodal shield at level of caxa IV; peritreme as in adult female.

Legs. Pretarsi of legs I–IV, shape of setae and chaetotaxy as in adult female. Lengths of legs: I, 282; II, 237; III, 225; IV, 312. Setae aciculate. Leg chaetotaxy as in female.

Material examined

Female holotype, two female and one male paratypes, on coconut palm leaves, Cocos nucifera L. ( Arecaceae ), Don Sak, Thailand. All collected in March 2011, by Gilberto J. de Moraes. Holotype female, paratype male and paratype female deposited in the Insect Museum, Department of Entomology, Kasetsart University, Bangkok, Thailand. Paratype female deposited in the Acarology Collection of Departamento de Entomologia e Acarologia, Escola Superior de Agricultura “Luiz de Queiroz”, Universidade de São Paulo, Piracicaba, São Paulo, Brazil.

Etymology

The name of the species was given after the former name ( Siam) of the country where the types were collected.

Remarks

This new species is closely related to Lasioseius cuppa Walter and Lindquist, 1997 . Female of L. siamensis sp. nov. differs from L. cuppa by having: 13 setae on tibia I (instead of 12; with two instead of three ventral setae); no platelets between genital and ventrianal shield (instead of with fragmented strip); pre-anal pores on the margin of the ventrianal shield, in transverse line with insertion of Jv4 (instead of anterolaterad of and slightly anterior to insertion of Jv4). Male of L. siamensis differs from L. cuppa by having pre-anal pores next to the margin of the shield, well posterior and laterad of insertion of Jv3 (instead of away from the margin, slightly posterior and mesad of insertion of Jv3).

Figures

Figure 1. Lasioseius siamensis Silva and Moraes, sp. nov. female. (A) Hypostome. (B) Chelicera. (C) Epistome. (D) Dorsum of idiosoma. (E) Venter of idiosoma. (F) Spermatheca. (G) Tarsus II. (H) Tarsus III. (I) Tibiotarsus IV.

Figure 2. Lasioseius siamensis Silva and Moraes, sp. nov. male. (A) Hypostome. (B) Chelicera and spermatodactyl. (C) Dorsum of idiosoma. (D) Venter of idiosoma.