Gaeolaelaps lankaensis, Joharchi & Khaustov & Ermilov, 2019

Joharchi, Omid, Khaustov, Alexander A. & Ermilov, Sergey G., 2019, Two new species of Gaeolaelaps Evans & Till (Acari: Laelapidae) from Sri Lanka, Zootaxa 4615 (3), pp. 563-576 : 564-569

Gaeolaelaps lankaensis sp. nov.

( Figures 1–17 )

Type material examined: Holotype, female, Sri Lanka, Sabaragamuwa Province, Polgampola , 06°27’ N, 080°12’ E, alt. 42 m, 24 January 2019, O. Joharchi, S.G. Ermilov & A.A. Khaustov coll., from forest soil-litter near the Thambadola Ella waterfall (in TSUMZ) . Paratype, one female, same data as holotype (in TSUMZ) .

Diagnosis (female). Dorsal shield without distinct reticulate ornamentation over whole surface, narrowing from level of setae r3, progressively tapering until s6, then subparallel from S1 to level of S4 until rounded posteriorly, bearing 35 pairs of moderately long and simple setae (22 pairs of podonotal setae on shield and 13 pairs of opisthonotal setae on shield, Z5 & S5 outside the shield). Tritosternum with pair of very long pilose laciniae, Sternal shield smooth almost throughout; bearing two pairs of smooth pointed setae, st1 outside the shield, metasternal poroids (iv3) located on minute platelets, ratio of shield length/width (at broadest level) 1.1. Genital shield ratio of length/ width (at broadest level) 2.8, with irregular longitudinal lines in anterior half≃enclosing two diagonal lines forming an inverted-V in posterior ≃ part of surface. Anal shield ratio of length/width (at broadest level) 1.1, cribrum small. Peritreme thin and short, barely reaching anterior margin of coxa II, post-stigmatal section well≃reduced. Palp tarsal claw three-tined, fixed digit of chelicera with four teeth distally and a larger proximal tooth, femur II with 10 setae.

Description. Female (n = 2)

Dorsal idiosoma ( Figs 1 , 6, 10 ). Idiosoma length 266–270, width 151–158. Dorsal shield 253–257 long, 120– 127 wide at r2 level, covering most of dorsal idiosoma, 80–85 wide at level of S1; without distinct reticulate ornamentation over whole surface, narrowing from level of setae r3, progressively tapering until s6, then subparallel from S1 to level of S4, until rounded posteriorly. Shield with 35 pairs of moderately long and simple setae, 22 pairs of podonotal setae on shield (j1–6; z1–6; s1–6; r2–5), r 6 in lateral soft cuticle, and 13 pairs of opisthonotal setae on shield (J1–5; Z1–4; S1–4), Z5 & S 5 in soft cuticle posterior to shield ( Fig. 10 ), Zx setae and unpaired supernumerary seta (Jx) absent ( Fig. 10 ). All setae smooth and uniform in length (podonotal setae 18–22; opisthonotal setae 15–18) and thickness, except Z5 (27–29), S5 (24–26), z1 (15–17) and J5 (22–24, with one or two barbs, Fig. 10 ), dorsal setae decreasing slightly in length from anterior to posterior. Shield with about eight pairs of discernible porelike structures, five on podonotum (id1, id4, id5, gd1, gd6) and three on opisthonotum (idm6, idl3, idl4), others indistinct, see Figures 1 and 6 .

Ventral idiosoma ( Figs 2 , 7–9 ). Tritosternum with pair of very long pilose laciniae (68–71), fused basally (4–6), columnar base 20–22 × 9–11 wide; presternal area lightly sclerotised, with a few transverse curved lines. Sternal shield (length 95–99) narrowest between coxae II (60–63), widest between coxa II–III (84–86), with straight anterior and posterior margin, with two pairs of smooth pointed setae (st 2 24–26, st 3 25–27), st1 (20–22) outside the shield ( Fig. 8 ), setae never reaching base of next posterior setae, one pair of lyrifissures (iv1) adjacent to anterior margin, and a pair of sub-oval poroids (iv2) between st2 and st3, surface of sternal shield without reticulate ornamentation, almost smooth, except some irregular longitudinal lines laterally ( Fig. 8 ), lateral margins alongside coxa II–III fused with endopodal plates. Metasternal setae st4 (18–20) inserted on soft cuticle posterior to sternal shield and metasternal poroids (iv3) located on minute platelets (Fig, 9). Endopodal plates III/IV elongate, narrow and curved. Genital shield tongue-shaped, length 89–93, maximum width 31–33, posterior margin slightly tapered, surface reticulated with irregular longitudinal lines in anterior which enclosing two diagonal lines forming an inverted-V in posterior part and a pair of simple setae st5 (13–15) ( Fig. 9 ). Shield flanked by a pair of minute narrow platelets; paragenital poroids located on soft cuticle lateral to shield near seta st5. Anal shield subtriangular, anterior margin rounded and triangular posteriorly, length 34–36, width 30–32, anterior half with lineate ornamentation, with a pair of lateral pores (gv3), para-anal setae (14–16) slightly shorter than post-anal seta (15–17), cribrum small. Opisthogastric cuticle with six pairs of smooth and uniform in length setae (15–18) (Jv1–Jv4, Zv1– Zv 2), except Jv3 (24–26) and Jv4 (31–33). Exopodal and parapodal platelets strip-like behind coxae IV. Peritreme short, barely reaching anterior margin of coxa II, peritrematal shield with small protrusion on outer margin, peritrematal shield narrow, free from exopodal shields, each shield bearing five discernible pore-like structures, a lyrifissure ip and a gland pore gp at level of between coxae II and III, two lyrifissures ip and a gland pore gp on post-stigmatic section ( Figs 2 , 7–9 ).

Gnathosoma ( Figs 3–5 , 11–13 ). Hypostomal groove with six transverse rows of denticles, each row with about 8–19 small teeth, and smooth anterior and posterior transverse lines ( Fig. 3 ). Hypostome with four pairs of setae, internal posterior hypostomal setae h1 longest (29–31), h2 (13–15), h3 (22–25), palpcoxal setae (pc) (17–19) ( Fig. 3 ). Anterior margin of epistome undulating, convex central part with few denticles, almost smooth, lateral processes densely denticulate ( Figs 4 , 11 ). Corniculi robust and horn-like, reaching mid-level of palp femur. Internal malae with median and lateral projections, fringed, inner lobes touching with outer lobes; labrum with pilose surface. Chaetotaxy of palps: trochanter 2, femur 5, genu 6, tibia 14, tarsus 15, all setae smooth and needle-like except al on palp femur and al, d1 on palp genu thickened and apically spatulate, palp tarsal claw three-tined ( Fig 12 ). Fixed digit of chelicera with four teeth of varying sizes distally and a larger proximal tooth, a setaceous pilus dentilis, dorsal cheliceral seta prostrate, arthrodial membrane with a rounded flap and normal filaments, cheliceral lyrifissures distinct, movable digit with two teeth ( Figs 5 , 13 ).

Legs ( Figs 14–17 ). Legs II and III short (223–229, 161–167), I and IV longer (322–329, 266–273). Chaetotaxy normal for free living Laelapidae : Leg I ( Fig. 14 ): coxa 0 0/1, 0/1 0, trochanter 1 0/1, 1/2 1, femur 2 2/1, 3/3 2, genu 2 3/2, 3/1 2, tibia 2 3/2, 3/1 2. Leg II ( Fig. 15 ): coxa 0 0/1, 0/1 0, trochanter 1 1/1, 0/2 0, femur 1 3/1, 2/2 1, genu 2 3/1, 2/1 2, tibia 2 2/1, 2/1 2 (all ventral setae thickened). Leg III ( Fig. 16 ): coxa 0 0/1, 0/1 0, trochanter 1 0/1, 0/2 1, femur 1 2/1, 1/0 1, genu 2 2/1, 2/1 1 (all ventral setae thickened), tibia: 2 1/1, 2/1 1. Leg IV ( Fig. 17 ): coxa 0 0/1, 0/0 0, trochanter 1 0/2, 0/1 1, femur 1 2/1, 1/0 1, genu 2 2/1, 3/0 1 (av thickened), tibia 2 1/1, 3/1 2 (all ventral setae thickened). Tarsi II IV with 18 setae (3 3/2, 3/2 3 + mv, md). All pretarsi with well developed paired claws and rounded pulvilli and a long thin stalk, ventral and lateral setae on tarsus II and III thickened.

Insemination structures: Not seen, apparently unsclerotised.

Male and immatures. Unknown.

Etymology. The specific name is derived from the type locality.

Differential diagnosis. The new species is unique within Gaeolaelaps by the following combination of characters: palp tarsal claw three-tined ( Fig. 12 ), st1 located outside sternal shield ( Fig. 8 ), dorsal shield with 35 pairs of moderately long and simple setae, Z5 & S5 on soft cuticle posterior to shield, without Zx setae and unpaired supernumerary seta (Jx) ( Figs 1 , 6 ), tritosternum with pair of very long pilose laciniae ( Fig. 2 ), peritreme short (barely reaching anterior margin of coxa II) and femur of leg II with ten (1 3/1, 2/2 1, al2 absent) setae instead of the usual 11. In the key to Gaeolaelaps species with short peritremes provided in Vatankhah et al. (2016), this species came to couplet 11, but the uncommon character state of 35 pairs of dorsal shield setae, makes couplet choice problematic. In the classification of Karg (1982), G. lankaensis falls into the angusta species group of Hypoaspis (Gaeolaelaps) , because its dorsal shield narrows from level of setae r3, and the shield lacks Zx setae on the opisthonotal region. Gaeolaelaps lankaensis is similar to G. tarsalis ( Bhattacharyya, 1968) and G. queenslandicus ( Womersley, 1956) (we followed here Nemati et al., 2018 and consider G. angustus ( Karg, 1965) as a junior synonymy of G. queenslandicus ) in general appearance and also having a three-tined palp tarsal claw, but Gaeolaelaps lankaensis can be easily distinguished from these two species by having 35 pairs of setae on the dorsal shield, short peritreme (barely reaching anterior margin of coxa II), without spine-like seta on femur of leg II, and with ten seate (al2 absent) (vs. 37 or 38 pairs in G. queenslandicus and 39 pairs in G. tarsalis , peritreme long in both species (reach well to coxa I) and also femur II armed with spine-like setae in both species, with 11 setae, (al2 present).

The new species also resembles G. atomarius ( Berlese, 1917) (sensu Van Aswegen & Loots, 1970) and G. khajooii Kazemi et al., 2014 which have a similar dorsal shield, but it can be easily distinguished from both species by having 35 setae on dorsal shield (38 in G. atomarius , z3 absent and 39 in G. khajooii ).

Figures

FIGURES 1–5. Gaeolaelaps lankaensis sp. nov., female. 1, dorsal idiosoma; 2, ventral idiosoma; 3, subcapitulum; 4, epistome; 5, chelicera.

FIGURES 6–13. DIC micrographs of Gaeolaelaps lankaensis sp. nov., female. 6, idiosoma in dorsal view; 7, idiosoma in ventral view; 8, sternal shield; 9, genital shield and opisthogastric area; 10, opisthonotal region; 11, epistome; 12, palp; 13, chelicera.

FIGURE 14–17. Gaeolaelaps lankaensis sp. nov., female. 14, leg I (trochanter-tibia); 15, leg II; 16, leg III; 17, leg IV.