Cosmolaelaps sejongi, Keum & Jung & Joharchi, 2017

Keum, Eunsun, Jung, Chuleui & Joharchi, Omid, 2017, New species and new records of the family Laelapidae (Acari: Mesostigmata) from Republic of Korea, Zootaxa 4353 (3), pp. 485-505 : 487-488

Cosmolaelaps sejongi sp. nov.

Figures 1–13 .

Specimens examined: Holotype, female, Taehwa River, Ulsan Metropolitan City, Republic of Korea, 35°32' N, 129°17' E, alt. 666 m, 12 May 2015, E. Keum coll., from soil around root of oak tree . Paratypes: two females, same data as holotype (deposited in PMANU) .

Description. Female. Dorsal idiosoma ( Fig. 1 ). Body length 372–401 and width 263–317. Dorsal shield covering entire idiosoma, width 336–340, shield with weak reticulation throughout, more distinct in podonotal section; dorsal shield bearing 39 pairs setae, 22 pairs on podonotal region (j1–6; z1–6; s1–6; r2–5) and 17 pairs on opisthonotal region (J1–5; Z1–5; S1–5; and two pairs of Zx); most dorsal setae elongate (38–45), scimitar-shaped ( Figs. 1, 3 ), except j1 (15–18) and Z5 (25–28) simple but thickened and abruptly tapering apically ( Figs. 2, 4 ) and z1 (10–13) setiform. Almost all setae long enough to reach well past base of next posterior seta, all setae smooth except Z5 lightly barbed ( Fig. 4 ). Shield with 15 pairs of discernible pore-like structures, nine on podonotum ( Fig. 1 ) and four on opisthonotum ( Fig. 1 ). Shape, position and relative length of setae shown in figures ( Figs 1–3 ).

Ventral idiosoma ( Figs 5–7 ). Tritosternal base (27–29 long × 7–9 wide) and pilose laciniae, length 52–54 ( Fig. 5 ). Presternal area with few distinct transverse striae. Sternal shield length 90–93, width 120–125, with slightly concave posterior margin; with three pairs of simple and subequal sternal setae [st1 (30–32), st2 (25–28), st3 (25– 28)] and two pairs of poroids (iv1 and iv2 slit-like, adjacent to setae st1 and between st2 and st3, respectively). Sternal shield smooth, without distinct reticulation. One pair of simple metasternal setae st4 (25–30) and pore-like iv3 inserted on soft cuticle posterior to sternal shield. Genital shield elongate, rounded posteriorly, width (75–78) and length (138–150). Surface with characteristic ornamentation including distinct V-shaped lines, abutting anal shield, and with one pair of simple genital setae st5 (25–28). Paragenital poroids (iv5) located on soft cuticle lateral to shield behind coxae IV. Anal shield subtriangular (length 70–75), width (53–55), bearing a pair of simple paranal setae (15–18), postanal seta (25–28) thickened, barbed, apically bent (hook shaped) and inserted on a small tubercle ( Figs. 5, 7 ) and with a pair of marginal pores (gv3); cribrum small. Soft opisthogastric cuticle surrounding genital and anal shields with one pair of sub oval metapodal plates (17–19 long × 5–7 wide) and 14 pairs of setae (20–28) (Jv1–Jv5, Zv1– Zv 5, UR1-UR4); Jv4, Jv5 and Zv5 thickened, abruptly tapering apically, other setae simple ( Figs. 5, 6 ). Peritreme long, extending to level of anterior margin of coxa I (near z1), peritrematal shield narrow, free from exopodal shields, each shield bearing three discernible pore-like structures, two lyrifissures ip and a gland pore gp on post-stigmatic section and also a small pore-like structure within peritreme at level of coxa III ( Fig. 5 ); anterior part of shield fused with dorsal shield.

Gnathosoma . Hypostome with three pairs of hypostomal setae [h1 (18–20), h2 (18–20), h3 (27–30)] and a pair of palpcoxal setae (pc) (23–25). Hypostomal groove with six rows of 11–14 denticles, and smooth anterior and posterior transverse lines, corniculi horn-like and parallel to each other, almost reaching mid-level of palp femur ( Fig. 8 ). Palp chaetotaxy normal (2–5–6–14 –15), setae uniform in shape; palp tarsal apotele two-tined. Anterior edge of epistome acuminate, irregularly denticulate ( Fig. 9 ). Fixed digit of chelicera with eight teeth (n=3) of various sizes and a setaceous pilus dentilis. Arthrodial brush present at base of movable digit, dorsal cheliceral setae short. Movable digit with two teeth ( Fig.10 ). Internal malae complex, with two pairs of lobes, inner lobes narrow, with serrated edges, outer lobes narrow, pointed, shorter than inner lobes, with strongly serrated edges.

Legs ( Figs 11–13 ).Tarsi I–IV each with a pair of claws and pulvillus. Legs II (238–267) and III (223–243) shorter than legs I (342–348) and IV (344–350). Chaetotaxy normal for free-living Laelapidae : Leg I: 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: coxa 0 0/1 0/1 0, trochanter 1 0/1 1/1 1, femur 2 3/1 2/2 1 (al2 strongly thickened), genu 2 3/1 2/1 2, tibia 2 2/1 2/1 2 ( Fig. 11 ). Leg III: coxa 0 0/1 0/ 1 0, trochanter 1 0/1 1/1 1, femur 1 2/1 1/0 1 (ad1 strongly thickened), genu 2 2/1 2/1 1, tibia 2 1/1 2/1 1 ( Fig. 12 ). Leg IV: coxa 0 0/1 0/0 0, trochanter 2 1/1 0/1 0, femur 1 2/1 1/0 1 (ad1 strongly thickened), genu 2 2/1 3/0 1, tibia 2 1/1 3/1 2 ( Fig. 13 ). Most leg setae relatively thick, with variation indicated in parentheses above. Tarsi II–IV with 18 setae 3 3/2 3/2 3 + mv, md, all setae simple and needle-like; all pre-tarsi with a well-developed ambulacral stalk, a pair of claws and three rounded pulvillar lobes, projecting well beyond claws.

Insemination structures: Not seen, apparently unsclerotised.

Male. Unknown.

Etymology. The species is named in memory of Sejong the Great (15 May 1397 – 8 April 1450), the fourth king of the Joseon-dynasty in Republic of Korea, who encouraged creativity and advancements in scientific technology and under whom the Hangeul (Korean alphabet) was created.

Differential diagnosis. The new species is unique within Cosmolaelaps genus because of the distinctive shape of the post anal seta (thickened, barbed and apically hook shaped), which is inserted on a small tubercle. Additional diagnostic features are the thickened and abruptly tapering setae j1, Z5, Jv4, Jv5 and Zv5. Seta Z5 is also lightly barbed.

Figures

FIGURES 1–10. Cosmolaelaps sejongi sp. nov., female. 1, dorsal idiosoma; 2, dorsal seta j1 enlarged (not to scale); 3, dorsal seta j3 enlarged (not to scale); 4, dorsal seta Z5 enlarged (not to scale); 5, ventral idiosoma; 6, ventral seta Jv5 enlarged (not to scale); 7, post anal seta enlarged (not to scale); 8, subcapitulum; 9, epistome; 10, chelicera.

FIGURES11–13. Cosmolaelapssejongi sp. nov., female.11, femur, genu andtibia II; 12, femur, genu and tibia III; 13, femur, genu and tibia IV.