Hypoaspis longicaudus, 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 : 495-498

Hypoaspis longicaudus sp. nov.

( Figures 22–31 )

Specimens examined: Holotype female, Uiseong-gun, Gyeongbuk province, Republic of Korea, 36°27' N, 128°23' E, alt. 148 m, 27 April 2012, E. Keum coll., from soil of organic apple orchard . Paratype: One female, same data as holotype (deposited in PMANU) .

Description. Female. Dorsal idiosoma ( Fig. 22 ). Length 871–880, width at level of r5 574–585. Dorsal shield oval, without lateral incisions, length 705–710, width at level of r5, 396–401 (n = 2), shield with weak reticulation, indistinct anteriorly, more distinct in opisthonotal region. Dorsal shield with 39 pairs of smooth and pointed setae, 22 pairs on podonotal shield (j1–6; z1–6; s1–6; r2–5), plus r6 off the shield, 17 pairs on the opisthonotal shield (J1–5, Z1–5, S1–5), including two pairs of Zx setae between J and Z setae; S5 longest (126–128) and not wavy, j3 (116–118) long, reaching past base of j4, j4 (110–112) reaching past of base of j5 (105–107). Setal lengths: j1 80– 82, j2 102–104, j6 106–108, z1 47–49, z5–6 104–107 and J1 93–95, J2 97–99, J3 102–105, J4 82–85 J5 48–50, Z5 123–125, Z4 75–77, S4 112–115. Shield with eight pairs of discernible pore-like structures; lyrifissures near the base of j1 large and slit-like, others smaller and ovoid. Six and three pairs of setae in R and UR series, respectively, on soft skin surrounding shield.

Ventral idiosoma ( Fig. 23 ). Tritosternal base length 52–56, width 22–25 wide, and pilose laciniae, length 117– 120; pre-sternal plates present, weakly reticulated. Sternal shield (length 277–280) narrowest between coxae II (115–118), widest between coxae II–III (225–230), with slightly concave anterior and posterior margins and three pairs of long, smooth pointed setae (st 1–3 65–67), reaching well past base of next posterior setae, one pair of lyrifissures adjacent to setae st 1, and a pair of poroids between st 2 and st 3; lateral surface of sternal shield with weak reticulation and central region without reticulation. Metasternal platelets absent, metasternal setae st4 (58– 60) and metasternal poroids located on soft cuticle. Endopodal plates II/III completely fused to sternal shield, endopodal plates III/IV roughly triangular and curved. Genital shield tongue-shaped, length 225–227, maximum width 105–107, posterior margin rounded, surface with lineate ornamentation, genital setae st5 (58–60) on edge of shield. Circular paragenital poroids located on soft cuticle close to st5. Anal shield rounded, subtriangular, length 115–118, width 100–103, anterior half with lineate ornamentation, unpaired post-anal seta (112–114) almost thrice as long as para-anal setae (45–47), cribrum small, a pair of circular lateral gland pores located on oval (25–27 long × 9–11 wide) sclerotised plates close to anal shield (labelled gv 3 in Figure 23 ). Opisthogaster with one pair of oval metapodal plates (39–41 long × 8–10 wide) and seven pairs of smooth setae (70–80) on weakly sclerotised cuticle. Exopodal plates behind coxa IV long and narrow. Peritrematal shield free posteriorly, post-stigmatal section conspicuous and narrow, with three pairs of discernible pore-like structures (apparently two lyrifissures ‘ ip’, and one gland pore ‘ gp’; see Fig. 23 ), peritreme extending from posterior margin of coxa III to near posterior margin of coxa I.

Insemination structures: Insemination ducts opening on posterior margin of coxa III, sacculus indistinct, apparently unsclerotised.

Gnathosoma . Epistome irregularly denticulate laterally, with median pointed projection ( Fig. 24 ). Hypostomal groove with six rows of 15–28 denticles, and smooth anterior and posterior transverse lines. Hypostome with four pairs of setae, internal posterior hypostomal setae h3 longest (77–79), h1 (45–47), h2 (27–29), palpcoxal (pc) (48– 50) ( Fig. 25 ). Corniculi robust and horn-like, reaching mid-level of palp femur. Palp setal numbers: trochanter 2, femur 5, genu 6, tibia 12, tarsus 15, all setae smooth and pointed, palp tarsal apotele two-tined. 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. Fixed digit of chelicera with nine small subterminal teeth, tooth level with pilus dentilis largest ( Fig. 26 ); pilus dentilis short, dorsal seta short, semi-erect, movable digit with two large subterminal teeth, arthrodial membrane a rounded flap with corona.

Legs ( Figs. 27–31 ). Legs II and III shortest (564–584, 594–604), I and IV both longer (693–703, 802–810) (excluding pretarsus). Chaetotaxy normal for free-living Laelapidae . Leg I: 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: coxa 0 0/1, 0/1 0, trochanter 1 0/1, 0/2 1, femur 2 3/1, 2/2 1 (macroseta pd1 110–112, pd2 68 70 long, Fig. 27 ), genu 2 3/1, 2/1 2 (pd2 longer 80–82, Fig. 27 ), tibia 2 2/1, 2/1 2. Leg III: coxa 0 0/1, 0/1 0, trochanter 1 1/1, 1/1 0, femur 1 2/1, 1/0 1 (ad1 longer 100–102, Fig. 28 ), genu 2 2/1, 2/1 1 (pd2 inserted on a small tubercle, ventral setae all thicker, Fig. 28 ), tibia 2 1/1, 2/1 1. Leg IV: coxa 0 0/ 1, 0/0 0, trochanter 1 1/1, 0/1 1, femur 1 2/1, 1/0 1 (macroseta ad1 125–127, ad2 95 97 longer, pd and ad2 inserted on small tubercles, Fig. 29 ), genu 2 2/1, 3/0 1 ( Fig. 29 ), tibia 1 2/1, 3/1 2. Tarsi II–IV with 18 setae 3 3/2, 3/2 3 + mv, md. On tarsus II, al1, pl1 and all ventral setae thicker ( Fig. 30 ). Tarsus IV with four macrosetae, ad2 (113–115), pd2 (125–127), pl2 (140–143) and pl3 (138–142) ( Fig. 31 ). All pretarsi with a pair of claws and a long thin membranous ambulacral stalk.

Males & immatures. Unknown.

Etymology. The name longicaudus (Latin longus, long and caudus, tail) refers to the very long post anal seta.

Differential diagnosis. Hypoaspis longicaudus has the following five unique character states for the genus: post anal seta very long, being almost 2.5 times longer than the para anal setae, S5 are the longest dorsal setae, gv3 is located on oval sclerotised plates close to the anal shield, and four long macrosetae on tarsus IV (ad2, pd2, pl2 and pl3) and some other leg setae are inserted on small tubercles (genu III pd2 and femur IV ad2, pd).

Notes. Hypoaspis sensu stricto is defined by the following character states: dorsal shield oval, without lateral incisions, bearing 35–40 pairs of setae including one or more pairs of Zx setae; some opisthonotal setae greatly elongated, especially Z4 (at least three times as long as J5); post-anal seta distinctly shorter than para-anals; hypostomal setae h3 distinctly longer than other hypostomal setae; greatly elongated macrosetae present on femora II and III and tarsus II with two subterminal blunt spines (setae al1 and pl1).

Our new species, Hypoaspis longicaudus sp. nov., has some character states that define Hypoaspis sensu lato and Hypoaspis sensu stricto. The characters that cause difficulties are: post-anal seta distinctly longer than paraanals (never seen before among species of Hypoaspis s. s.), S5 longest dorsal setae (versus Z4 longest dorsal setae among species of Hypoaspis s. s.) and Z4 not three times as long as J5 (Z4 about three times as long as J5 among species of Hypoaspis s. s.). In all other respects, H. longicaudus belongs to Hypoaspis sensu stricto. Therefore, if we do not use these characters states to define Hypoaspis s. s. then we have too small number of diagnostic character states of this genus. In the other hand at the present time, we do not think to create a new monotypic genus to accommodate the new species would help to clarify the taxonomic problems existing within the family Laelapidae . Therefore, we provisionally place this species in Hypoaspis sensu lato until a comprehensive revision of all these genera resolves its relationships.

Figures

FIGURES 22–26. Hypoaspis longicaudus sp. nov., female. 22, dorsal idiosoma; 23, ventral idiosoma; 24, epistome; 25, subcapitulum; 26, chelicera.

FIGURES 27–29. Hypoaspis longicaudus sp. nov., female. 27, femur, genu and tibia II; 28, femur, genu and tibia III; 29, femur, genu and tibia IV.

FIGURES 30–31. Hypoaspis longicaudus sp. nov., female. 30, tarsus II; 31, tarsus IV.