Julolaelaps gigas, Joharchi & Keum & Jung, 2023

Joharchi, Omid, Keum, Seoyoung & Jung, Chuleui, 2023, The first record of the genus Julolaelaps Berlese (Acari, Mesostigmata, Laelapidae) in Republic of Korea and description of a new species on a captive giant African millipede (Spirostreptidae, Archispirostreptus), ZooKeys 1180, pp. 51-65 : 51

Julolaelaps gigas sp. nov.

Figs 1-5 , 6-9 , 10, 11 , 12-16

Material examined.

Holotype. Republic of Korea • ♀; Sangju , Silkworm and Insect Management Center; 36°57'N, 128°15'E; 19 May 2020; S. Keum leg.; on captive giant African millipede, Archispirostreptus gigas ( Spirostreptida : Spirostreptidae ); NIBRIV 0000905722 . Paratypes. Republic of Korea • 2♀ 2♂; same data as for holotype; NIBRIV 0000905723, NIBRIV 0000905724, NIBRIV 0000905725, NIBRIV 0000905726 .

Diagnosis.

Dorsal shield smooth, without reticulation, bearing 22 pairs of minute acicular setae, setae Z5 conspicuously longer than other setae on shield, podonotal and opisthonotal parts of dorsal shield slightly hypotrichous, setae in z - and s/S-series displaced laterally (on soft cuticle) and some missing (z1, z6, J3); posterior margin of shield somewhat truncated; dorsal shield reduced, not covering entire idiosoma, opisthogastric and lateral soft cuticle with 37 pairs of setae, including 23 pairs of r - R - UR setae. Sternal shield reduced, bearing only st1 and st2, eroded posteriorly, st3 and metasternal setae (st4) inserted on unsclerotized cuticle, epigynal shield drop-shaped, parapodal plates broadly thickened, extending behind coxae IV, endopodal plates III/IV broadly thickened, peritreme relatively long and rather broad, extending to anterior level of coxa II, cheliceral fixed digit with 2-3 teeth. Chaetotaxy of legs normal for free-living Laelapidae , except tibia III with nine setae (two posterolateral setae present) and genu IV with 10 setae (with two posterolateral setae). Male with separate sternogenital and anal shields, chelicerae with edentate digits including a regressed fixed digit and a stylet-like movable digit bordered by a very long spermatodactyl.

Description.

Female (N = 3). Figs 1 - 9 , 12-14 . Dorsal idiosoma (Figs 1 , 12 ). Length 906-925, width 620-649. Dorsal shield length 687-696, width 391-395, posteriorly somewhat truncate, reduced, not covering entire idiosoma, some dorsal setae left in the soft cuticle lateral to shield, becoming hypertrichous cuticle surrounding dorsal shield, without distinct reticulate ornamentation over whole surface; with 22 pairs of minute acicular setae, 13 pairs of podonotal setae, plus nine pairs of setae on lateral soft cuticle (s1, s2, s6, r1-6), nine pairs of opisthonotal setae, plus 21 pairs of setae on lateral soft cuticle (including S1-5 and R1-7); Zx, unpaired or asymmetrical setae and z1, z6, J3 absent, setae similar in length (9-15) and thicknesses; clonal setae Z5 (26-31) longer than other setae on shield. Muscle insertions prominent as desclerotised circular patches. Dorsal shield with 22 pairs of discernible pore-like structures, including only five pairs of gland openings (gd1, gd4, gd6, gd8, gd9) and 17 pairs of poroids. Shape, position and relative length and thicknesses of setae shown in Figs 1 , 12 .

Ventral idiosoma (Figs 2 , 13 ). Tritosternum with paired pilose laciniae (105-113), short base 30-35 × 23-27 wide; presternal platelets absent. Sternal shield reduced (59-63 × 134-142 wide), shield with two pairs of smooth sternal setae [st1, st2 (20-26)], and two pairs of poroids (iv1, iv2), eroded posteriorly, surface without reticulate ornamentation, smooth, st3 (30-32) and metasternal setae (st4, 29-31) inserted on soft integument, metasternal poroids (iv3) apparently absent (Figs 2 , 13 ), shield fused anterolaterally to narrow endopodal strip between coxae I and II, endopodal plates III/IV broadly thickened (Figs 2 , 13 ). Epigynal shield drop-shaped, with an obvious (narrow) neck at level of coxae IV, protruding at level between setae st5 and Jv1, width (65-70) and length (228-235), anterior and posterior margins rounded, with some irregular longitudinal and oblique lines, otherwise relatively smooth, bearing a pair of simple setae st5 (20-23) inserted on lateral margins of shield, near level of posterior edge of coxae IV; paragenital poroids iv5 located on soft cuticle lateral to shield near seta st5 (Figs 2 , 13 ). Anal shield subtriangular, rounded anteriorly, length 133-138, width 108-114, surface without reticulate ornamentation, smooth, para-anal setae (23-27) shorter than post-anal seta (30-35), cribrum well developed, with 3-4 irregular rows of spicules, each extending from cribrum to near base of post-anal setae; anal opening located at anterior level of shield; pair of glands gv3 inserted on shield lateral margins, at level para-anal setae (Figs 2 , 13 ). Soft opisthogastric cuticle surrounding epigynal and anal shields with one pair of suboval metapodal plates (38-43 long × 13-18 wide) and seven pairs of smooth setae (Jv1-Jv3, Jv5, Zv1-Zv3), setae more or less same in length (18-24) and thickness (Figs 2 , 13 ). Peritreme relatively long and broad, extending to anterior level of coxa II, peritrematal shield narrow, slightly expanded anteriorly, each shield bearing three discernible pore-like structures, a gland pore gp2 at level of coxa III, a lyrifissures ip3 and a gland pore gp3 on barely developed poststigmatic section (Figs 2 , 13 ), anterior part of shield not fused with dorsal shield; parapodal platelets broadly thickened, extending behind coxae IV, bearing gland pore gv2; exopodal platelets absent (Figs 2 , 13 ).

Gnathosomal structures (Figs 3-5 , 14 ). Epistome triangular, with pointed apex and smooth (Fig. 4 ). Hypostomal groove with six transverse rows of denticles, each row with 3-5 denticles, with smooth anterior and posterior transverse lines (Fig. 3 ). Hypostome with four pairs of smooth setae, pc (24-26)> h1 = h2 (18-21)> h3 (14-16) (Fig. 3 ). Corniculi robust and horn-like, extending slightly beyond palpfemur. Internal malae with one pair of smooth median projections, flanked by lobes with fimbriate anterior margin; labrum with pilose surface; supralabral process not distinct. Chaetotaxy of palps: trochanter 2, femur 5, genu 6, tibia 14, tarsus 15, all setae smooth; palpfemur with seta d3 thickened and al paddle-like; palpgenu with al1 stout, blunt, al2 thickened and spatulate; palptarsal apotele two-tined. Fixed digit of chelicera with 2-3 teeth and long pilus dentilis, dorsal cheliceral seta relatively thick and short, arthrodial membrane with a rounded flap and normal filaments; movable digit with two mid-sized teeth (Figs 5 , 14 ).

Insemination structures. Not seen, apparently unsclerotized.

Legs. (Figs 6-9 ). Legs II and III short (600-650, 625-655), I and IV longer (657-680, 739-755). Chaetotaxy normal for free-living Laelapidae : Leg I (Fig. 6 ): coxa 0-0/1, 0/1-0, trochanter 1-0/1, 1/2-1, femur 2-3/1, 2/3-2, genu 2-3/2, 3/1-2, tibia 2-3/2, 3/1-2. Leg II (Fig. 7 ): 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. Leg III (Fig. 8 ): coxa 0-0/1, 0/1-0, trochanter 1-1/1, 0/1-1, femur 1-2/1, 1/0-1 (ad thickened and inserted on small tubercles), genu 2-2/1, 2/1-1 (ad1 and pd1 inserted on small tubercles), tibia: 2-1/1, 2/1-2. Leg IV (Fig. 9 ): coxa 0-0/1, 0/0-0, trochanter 1-1/1, 0/1-1 (ad thickened), femur 1-2/1, 1/0-1 (ad1 longest, ad1 and ad2 inserted on small tubercles), genu 2-2/1, 3/0-2, tibia 2-1/1, 3/1-2. Tarsi II-IV with 18 setae (3-3/2, 3/2-3 + mv, md); with some ventral and lateral setae thickened. All pretarsi with well-developed paired claws, rounded pulvilli and normal ambulacral stalk.

Male (N = 2). Figs 10 , 11 , 15 , 16 . Dorsal idiosoma. Length 760-768, width 525-530. Dorsal shield length 647-653, width 345-350; ornamentation and chaetotaxy as in female.

Ventral idiosoma. (Figs 10 , 15 ). Sternal, genital, endopodal, ventral shields fused into sternogenital shield, 327-333 long from anterior to posterior margins of shield, 175-180 wide at level of st2, 160-165 at st3 level and 118-123 at st5 level; shield with six pairs of simple sternal setae (st1-5 and Jv1) (19-30), and two pairs of poroids; anal shield free, length 117-123, width 93-98, surface without reticulate ornamentation, smooth, post-anal seta (25-28) slightly longer than para-anals (18-23), cribrum well developed, with 3-4 irregular rows of spicules, each extending from cribrum to near base of post-anal setae; anal opening located at anterior level of shield; pair of glands gv3 inserted on shield lateral margins, at level para-anal setae (Figs 10 , 15 ). Soft opisthogastric and lateral cuticle with 10-12 pairs of setae. Peritremes, peritrematal shields and other ventral structures similar to those in female.

Gnathosoma. (Figs 11 , 16 ). Chelicerae with edentate digits including a regressed fixed digit and a stylet-like movable digit bordered by a long spermatodactyl, pilus dentilis long. Other gnathosomal structures similar to those in female.

Legs. Chaetotaxy as in female.

Etymology.

The name of this species refers to its occurrence on giant African millipede of the species Archispirostreptus gigas ( Spirostreptida : Spirostreptidae ).

Differential diagnosis.

The female of the new species is unique within Julolaelaps because of its conspicuously reduced sternal shield, bearing only two pairs of sternal setae (st1, st2), eroded posteriorly and endopodal plates III/IV broadly thickened. In other features the new species is closest to J. vandaelensis Maes, 1983 in having a genital shield narrower than anal shield, peritreme almost reaching anterior margin of coxae II and dorsal shield with 22 pairs of setae. It is distinguished from this species by the uniform minute acicular dorsal setae and the reduced dorsal shield, not covering entire idiosoma, leaving an unsclerotised cuticle surrounding the dorsal shield.

Figures

Figures 1 - 5. Julolaelaps gigas sp. nov., female, with symbols for chaetotactic notation of idiosomal setae 1 dorsal idiosoma 2 ventral idiosoma 3 subcapitulum 4 epistome 5 chelicera, lateral view.

Figures 6 - 9. Julolaelaps gigas sp. nov., female, with symbols for chaetotactic notation of legs setae 6 leg I (trochanter-tibia, dorsal aspect) 7 leg II (trochanter-tibia, dorsal aspect) 8 leg III (trochanter-tarsus, dorsal aspect) 9 leg IV (trochanter-tibia, dorsal aspect).

Figures 10, 11. Julolaelaps gigas sp. nov., male 10 ventral idiosoma 11 chelicera, lateral view.

Figures 12 - 16. Differential Interference Contrast (DIC) micrographs of Julolaelaps gigas sp. nov., female 12 idiosoma in dorsal view 13 idiosoma in ventral view 14 chelicera in lateral view, male 15 idiosoma in ventral view 16 chelicera in lateral view.