Cosmolaelaps trichiurus, Joharchi & Ermilov & Khaustov, 2020

Joharchi, Omid, Ermilov, Sergey G. & Khaustov, Alexander A., 2020, Two new species of Cosmolaelaps Berlese (Acari: Laelapidae) from Sri Lanka, Zootaxa 4743 (2), pp. 151-166 : 159-164

Cosmolaelaps trichiurus sp. nov.

( Figures 25–40 )

Type material: 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 (adult female). Dorsal shield covering most of the idiosoma, with reticulate ornamentation over whole surface, narrowing from level of setae r3, progressively tapering until rounded posteriorly, bearing 39 pairs setae. Most setae long enough to reach well past base of next posterior seta, all setae abruptly taper apically ( Figs 25 , 30, 32 ), except j1, z1, Z5 very short (7–10) and S5 longest (44–46). Sternal shield smooth almost throughout; anterior margin indistinct and posterior margin almost straight, bearing three pairs of setae and two pairs of large slit-shape pore-like structures ( Fig. 33 ), ratio of shield length/width (at broadest level) 1. Genital shield elongated, posterior margin of genital shield almost reaches anterior margin of anal shield≃ ( Figs 26 & 31 ), ratio of length/width (at broadest level) 3.2, surface without any distinct reticulation, almost completely smooth ( Fig. 34 ). Anal shield ratio of length/width≃(at broadest level) 1.8 and cribrum small, length of post-anal seta almost twice ≃

para-anal setae. Peritreme long, extending to posterior of coxa I, post-stigmatal section of peritrematal shield oval, its tip extending to mid-level of coxa IV. Fixed digit of chelicera with six teeth in two rows, dorsal cheliceral setae thickened, arthrodial membrane reduced to a lobe and without filaments. Femur I and genu III with 12 and 8 setae, respectively.

Description. Female (n= 2). Dorsal idiosoma ( Figs 25 , 30 & 32 ). Dorsal shield 316–318 long, 160–162 wide, covering most of dorsal idiosoma, reticulated over whole surface, narrowing from level of setae r3, progressively tapering until rounded posteriorly. Shield with 39 pairs of long setae, 22 pairs of podonotal setae on shield (j1–6; z1–6; s1–6; r2–5), and 17 pairs of opisthonotal setae on shield (J1–5; Z1–5; S1–5; and two pairs of Zx), supernumerary setae Jx between J -series absent, most setae long enough to reach well past base of next posterior seta (28–38 long), all setae smooth and uniform in thickness and abruptly tapered apically ( Fig. 32 ), except j1, z1, Z5 very short (7–10) and S5 longest (44–46). Soft cuticle surrounding dorsal shield with six pairs setae (r6, R2–R4 and UR5–6) setae. Shield with about 14 pairs of discernible pore-like structures, including ten poroids (id1, id2, id4, id5, idm1, idm2, idm3, idm5, idm6, idl1) and four gland openings (gd1, gd2, gd6, gd9), others indistinct ( Figures 25 and 30 ).

Ventral idiosoma ( Figs 26 , 31, 33 & 34 ). Tritosternum with paired pilose laciniae (58–60), fused basally (2–4), columnar base 15–17 × 10–12 wide; presternal area poorly sclerotised, granulate-lineate ( Figs 26 & 31 ). Sternal shield (length 99–102) narrowest between coxae II (73–75), widest (104–106), anterior margin completely indistinct and posterior margin almost straight; bears three pairs of smooth pointed setae (st1 22–24, st2 21–23, st3 21– 23), not reaching base of next setae, one pair of lyrifissures adjacent to setae st1, and a pair of poroids between st2 and st3; sternal shield smooth almost throughout ( Fig. 33 ). Metasternal setae st4 (22–24) and metasternal poroids located on soft integument; metasternal platelets absent. Endopodal plates II/III completely fused to sternal shield, endopodal plates III/IV elongate, narrow and curved. Genital shield tongue-shaped, sides almost parallel, elongated, length 134–136, maximum width 40–42, surface without any distinct reticulation, almost completely smooth ( Fig. 34 ), posterior margin of genital shield almost reaches anterior margin of anal shield ( Figs 26 & 31 ). Shield flanked by pair of minute, slightly elongate paragenital plaetelets; paragenital poroids iv5 located on soft cuticle lateral to shield near seta st5. Anal shield subtriangular, rounded anteriorly, length 52–54, width 36–38, anterior half faintly lineate-reticulate, post-anal seta (20–22) twice as long as para-anal setae (10–12), cribrum small, with 3–4 irregular rows of spicules, limited to region posterior to post-anal seta; anal poroids gv3 on anterolateral margin of anal shield. Soft opisthogastric cuticle with pair of oval and slightly elongate metapodal plates (10–12 long × 2–4 wide), and 12 pairs of smooth setae (Jv1–Jv5, Zv1–Zv 3) and four pairs of poroids including iv5. Exopodal and parapodal platelets not fused, strip-like extending narrowly behind coxae IV. Peritreme extending anteriorly to posterior level of coxa I, peritrematal shield narrow, expanded anteriorly, free from exopodal shields, each shield bearing five pore-like structures, a lyrifissure ip and a gland pore gp at level of coxa III, two lyrifissures ip and a gland pore gp on post-stigmatic section ( Fig. 26 ).

Gnathosoma ( Figs 27–29 , 35–36 ). Epistome subtriangular and irregularly denticulate ( Fig. 28 ). Hypostomal groove with seven transverse rows of denticles, each row with 8–15 small denticles, with smooth anterior transverse lines. Hypostome with four pairs of setae, internal posterior hypostomal setae h3 (30–32), h1 (24–26), h2 (13–15), palpcoxal pc (22–24) ( Fig. 27 ). Corniculi robust and horn-like, extending slightly beyond palptrochanter. Chaetotaxy of palps: trochanter 2, femur 5, genu 6, tibia 14, tarsus 15, all setae smooth and needle-like except except al1 on palp femur and al1, d1 on palp genu thickened and apically spatulate, palp tarsal apotele two-tined ( Fig. 35 ). Fixed digit of chelicera with an offset and most distal large tooth (gabelzhan), followed five variously sized teeth in two rows, a setaceous pilus dentilis, dorsal cheliceral setae thickened prostrate, arthrodial membrane reduced to a lobe and without filaments; cheliceral lyrifissures indistinct ( Fig. 29 ).

Legs ( Figs 37–40 ). Legs II (232–237) and III, (206–195) short, I (306–309) and IV (278–286) longer. Chaetotaxy normal for free-living Laelapidae : Leg I ( Fig. 37 ): coxa 0-0/1, 0/1-0, trochanter 1-0/1, 1/2-1, femur 2-2/1, 3/2-2 (pv3 absent), genu 2-3/2, 3/1-2 (pv slightly thickened), tibia 2-3/2, 3/1-2 (ventral setae slightly thickened). Leg II ( Fig. 38 ): coxa 0-0/1, 0/1-0, trochanter 1-0/1, 0/2-1, femur 2-3/1, 2/2-1, genu 2-3/1, 2/1-2, tibia 2-2/1, 2/1-2 (ventral setae slightly thickened). Leg III ( Fig. 39 ): coxa 0-0/1, 0/1-0, trochanter 2-1/1, 0/1-0, femur 1-2/1, 1/0-1, genu 2- 2/1, 2/0-1 (pv absent), tibia: 2-1/1, 2/1-1 (ventral setae thickened). Leg IV ( Fig. 40 ): coxa 0-0/1, 0/0-0, trochanter 2-1/1, 0/1-1, femur 1-2/1, 1/0-1, genu 2-2/1, 3/0-1, tibia 2-1/1, 3/1-2. Tarsi II-IV with 18 setae (3- 3/2, 3/2-3 + mv, md); some ventral and lateral setae on tarsi II-III thickened. All pretarsi with well-developed paired claws, rounded pulvilli and normal ambulacral stalk.

Insemination structures: Not seen, apparently unsclerotised.

Male and immatures. Unknown.

Etymology. The species name trichiurus (Greek thrix, hair + oura, tail) refers to the tail-like appearance of the setae S5.

Differential diagnosis. Cosmolaelaps trichiurus is similar in general appearance and the shape of the dorsal setae to C. gladii ( Karg, 1993) and Cosmolaelaps dioscorea Joharchi, Fan & Arjomandi, 2017 described from Galápagos Islands and Fiji, respectively. Cosmolaelaps trichiurus can be easily distinguished from these two species by S5 much longer than other dorsal setae (vs. S 5 in the same size with other dorsal setae in both species), genital shield elongated, posterior margin of genital shield almost reaches anterior margin of anal shield (genital shield not elongated in both species), length of post-anal seta almost twice that of para-anal setae (vs. length of post-anal seta shorter or at most subequal of para-anal setae but never longer in both species), fixed digit of chelicera with six teeth, dorsal cheliceral setae thickened, arthrodial membrane reduced to a lobe and without filaments (fixed digit of chelicera with 11 and eight teeth in C. gladii and C. dioscorea , respectively, cheliceral setae not thickened and arthrodial membrane with a rounded flap and normal filaments in both species). According to shape of dorsal setae, C. trichiurus in the classification of Karg (1981), falls into the nasoseta species group of Hypoaspis (Cosmolaelaps) , but C. trichiurus is distinguished easily from all species in nasoseta species group by following combination of unique characters: (1) dorsal shield narrowing from level of setae r3, progressively tapering until rounded posteriorly and most setae long enough to reach well past base of next posterior seta, all setae abruptly taper apically (except j1, z1, Z5 very short) and setae S5 much longer than other dorsal setae; (2) sternal shield smooth almost throughout; anterior margin indistinct and posterior margin almost straight; (3) genital shield elongated, posterior margin of genital shield almost reaches anterior margin of anal shield and surface almost completely smooth; (4) length of post-anal seta almost twice of para-anal setae; (5) fixed digit of chelicera with six teeth, dorsal cheliceral setae thickened and arthrodial membrane reduced to a lobe (filaments absent); (6) Femur I (2-2/1, 3/2-2) and genu III (2-2/1, 2/0-1) with 12 (pv3 absent) and 8 (pv absent) setae, respectively.

Figures

FIGURES 25–29. Cosmolaelaps trichiurus sp. nov., female. 25, dorsal idiosoma; 26, ventral idiosoma; 27, subcapitulum; 28, epistome; 29, chelicera.

FIGURES 30–36. DIC micrographs of Cosmolaelaps trichiurus sp. nov., female. 30, idiosoma in dorsal view; 31, idiosoma in ventral view; 32, general view of some dorsal setae; 33, sternal shield; 34, genital shield; 35, palp; 36, subcapitulum.

FIGURE 37–40. Cosmolaelaps trichiurus sp. nov., female. 31, leg I (trochanter-tibia); 32, leg II; 33, leg III; 34, leg IV.