Vulgarogamasus edurus, Negm & Gotoh, 2018

Negm, Mohamed W. & Gotoh, Tetsuo, 2018, Mites of the family Parasitidae Oudemans, 1901 (Acari: Mesostigmata) from Japan: a new species of Vulgarogamasus Tichomirov, 1969, and a key to Japanese species, Zootaxa 4429 (2), pp. 379-389 : 380-384

Vulgarogamasus edurus sp. nov.

[Japanese name: Ken-yadoridani]

( Figs. 1−22 )

Female (holotype, average for three paratypes in parentheses)

Dorsal idiosoma. Dorsum divided into two shields, podonotal 393 (410) µm length along midline, 436 (420) µm width at level of setae r3, and opisthonotal 320 (300) µm length, 462 (452) µm width, the two shields are overlapping near the centre and gradually separating towards lateral corners. Podonotal shield ( Fig. 1 ) with striations on lateral margins; with 21 pairs of simple setae, of these j1 58 (65), z1 20 (18), j2 66 (70), j3 70 (62), r3 130 (125) the longest, and a pair of distinct lyrifissures posteriad z1; setae z1 distinctly shorter than distance between z1 and j1. Opisthonotal shield ( Fig. 2 ) completely reticulated; with 24 pairs of setae, of approximate length J1 60 (62), J2 63 (60), J3 63 (61), J5 65 (64), Z1 74 (76), R1 55 (54).

Ventral idiosoma. Tritosternum normal in shape, with long narrow base 25 (26) and pilose laciniae 35 (33); presternal region with 3–4 transverse lines and two subtriangular presternal shields ( Fig. 5 ); sternal shield strongly reticulated, with three pairs of setae st1 23 (25), st2 20 (19), st3 19 (20), st1–st3 78 (80), st2–st2 57 (56) and two pairs of lyrifissures, the posterior pair of lyrifissures located equidistant between sternal setae st2 and st3 ( Fig. 5 ). Metasternal shields with one pair of setae st4 16 (18), st4–st4 56 (58) and a pair of lyrifissures; genital shield triangular, with rounded endogynium. Peritremes extend to level between coxae I & II. Opisthogastric shield 156 (160) (length from genital shield base to post-anal seta), completely reticulated ( Fig. 3 ); with eight pairs of setae excluding the para-anals and the post-anal seta.

Gnathosoma . Corniculi short 42 (44); three pairs of hypostomal setae and a pair of palpcoxal setae present, h1 120 (122), h2 88 (85), h3 91 (98), pcx 86 (88) ( Fig. 6 ); anterolateral seta of the palp-femur deeply branched while al1 and al2 of palp-genu entire ( Fig. 7 ); epistome trispinate and stout, with central prong 35 (33) little longer than lateral ones 27 (29) ( Fig. 8 ). Movable digit of chelicera 118 (122) with three teeth; the fixed digit with eight teeth (five large and three small) and a pilus dentilis, one minute tooth located distally and the two proximal teeth broad, with blunt tip ( Figs. 4 , 9 ).

Legs. Leg I 843 (860), leg II 633 (602), leg III 554 (542), leg IV 890 (915).

Deutonymph (average for 3 paratypes)

Dorsal idiosoma. Dorsum divided into two shields, podonotal 306 (320) length, 300 (285) width, and opisthonotal 188 (200) length, 290 (282) width, at widest point. The two shields are well separated with soft integument. Podonotal shield ( Fig. 10 ) with striations along its lateral margins; with 20 pairs of simple setae, of these j1 44 (46), z1 16 (14), j2 42 (45), j3 47 (44), j4 49 (45), j5 45 (46), j6 38 (34), r3 110 (122) the longest; a pair of distinct lyrifissures located posteriad z1; setae z1 shorter than distance between z1 and j1. Opisthonotal shield ( Fig. 11 ) completely reticulated; with 13 pairs of setae, of these J1 35 (34), J2 38 (37), J3 38 (38), J4 40 (37), J5 45 (44).

Ventral idiosoma. Tritosternum normal, with rectangular base 83 (80) length and pilose laciniae 163 (166). Sternal shield ( Fig. 15 ) 224 (230) length along midline, entirely reticulated, with longitudinal lines along lateral edges, slightly concave anteriorly, with three pairs of setae st1 50 (51), st2 35 (37), st3 28 (26), distances between sternal setae st1–st2 82 (80), st2–st3 51 (53), st2–st2 94 (96), setae st4 and st5 off shield, on soft cuticle. Opisthogaster represented by soft cuticle, one pair of small irregular-shaped medapodal shields present, one pair of minute setae directly located posteriad coxae IV, opisthogaster with seven pairs of pre-anal setae in central area posterior to anal shield, setae ZV3 missing but bases distinctly visible ( Fig. 16 ). Anal shield 93 (100) length, 97 (93) width, reticulated and with one pair of simple setae 42 (45) located laterally on shield, in addition to a pair of para-anal setae 18 (20) and a post-anal seta 22 (24).

Gnathosoma . Corniculi short 27 (30). Hypostomal and palpcoxal setae ( Fig. 17 ) present, h1 45 (46), h2 36 (37), h3 40 (42), pcx 40 (45); epistome trispinate, with median prong 27 (28) longer than lateral ones 16 (18) ( Fig. 18 ); anterolateral setae of the palp-femur branched while al1 and al2 entire on palp-genu, as in female. Movable digit of chelicera 88 (90) with three teeth, the fixed digit with 11 teeth (seven large and four minute teeth distally) and a pilus dentilis ( Fig. 12 ).

Legs. Leg I 700 (734), leg II 487 (476), leg III 422 (431), leg IV 654 (662).

Male (average for three paratypes)

Dorsal idiosoma. Dorsum strongly sclerotised and separated into two shields by a transverse suture. Podonotal shield 397 (412) µm length, 430 (422) µm width, with lateral striations, with 21 pairs of normal setae, r3 the longest 116 (122). Opisthonotal shield 345 (333) µm length, 426 (412) µm width, completely reticulated; with 25– 26 pairs of simple setae.

Ventral idiosoma. Tritosternum with a reduced base 10 (12) and pilose laciniae 66 (70); two subtriangular presternal shields present; holoventral shield with five pairs of setae and three pairs of lyrifissures in the area between coxae of legs I-IV, distances between setae st1–st2 94 (97), st2–st3 60 (58), st3–st4 55 (57), st4–st5 71 (77), st2–st2 97 (102), entirely reticulated except the area lateral to the first pair of lyrifissures. The genital orifice opens at the anterior margin of holoventral shield; peritremes extend to level between coxa I & II; opisthogastric shield completely reticulated, with para-anals slightly shorter than the post-anal seta.

Gnathosoma . Corniculi short 27 (30); three pairs of hypostomal setae and a pair of palpcoxal setae present, h1 52 (50), h2 32 (35), h3 48 (51), pcx 44 (47) ( Fig. 19 ); epistome trispinate, with prongs shorter than in female and deutonymph ( Fig. 20 ), central prong 10 (9), lateral prongs 6 (7); anterolateral setae on the palp-femur and palpgenu as in female; movable digits of chelicerae 84 (88) unidentate and with spermatotremes ( Figs 13 , 21 ).

Legs. Leg II with apophyses on femur, genu and tibia ( Figs 14 , 22 ). Leg I 880 (892), leg II 642 (655), leg III 570 (583), leg IV 820 (803).

Etymology. The name of the new species is derived from Latin word edurus meaning hard and refers to its rigid or tough sclerotised body.

Type material. Holotype female and 9 females, 6 males and 7 deutonymph paratypes were collected from a mixture of leaf litter and soil at Ibaraki University, Ami , Ibaraki Prefecture, 36° 02' 09" N, 140° 12' 54" E, 10 November 2017, coll. M. W. Negm. Type specimens will be deposited in the National Museum of Nature and Science ( NMNS), Tsukuba, Ibaraki Prefecture, Japan .

Remarks. The new species is closely related to Vulgarogamasus fujisanus ( Ishikawa, 1972) , originally described as Eugamasus fujisanus Ishikawa, 1972 , from female specimens found in a pit “Kaminari-ana” at Kansuyama, Shizuoka Prefecture. However, the new species was extracted from leaf litter and soil, mostly in association with collembolan insects. Also, the new species is relatively close to V. oligochaetus Gu & Huang (Gu & Huang, 1993) and V. zhenningensis Gu & Wang (Gu et al., 1987) collected from a bird nest and Rattus norvegicus Berkenhout (Mammalia: Rodentia ), respectively. However, the former differs from V. edurus in having only two pairs of sternal setae located on the sternal shield, and in the shape of epistome, while the latter differs in having both setae r3 and cheliceral digits distinctly longer. Table 3 lists the interspecific variations between females of V. edurus and its closely related species described from China.

Since the new species is most similar to V. fujisanus , females of the two species were investigated in detail. By the examination of the holotype female of V. fujisanus (National Museum of Nature and Science, Tsukuba, Japan) and based on the original designation of species, V. fujisanus and V. edurus are similar in having strongly reticulated dorsum and venter, trispinate epistome, and a relatively similar hypostome. However, the following taxonomic features separate their females ( V. fujisanus vs. V. edurus ): the former has distinctly longer idiosomal setae than the latter ( Table 2 shows the differences in some setal measurements between the two comparable species), setae r3 261 µm vs. 130 (125) µm; setae z1 64 µm longer than distance between bases of z1 and j1 vs. z1 20 (18) shorter than distance between z1 and j1; 10 pairs of opisthogastric setae (excluding para-anals and post-anal seta) vs. eight pairs (one pair each of JV and ZV series absent); epistome with central prong much longer and thicker than lateral ones vs. central prong 35 (33) little longer than lateral ones 27 (29), but the same thickness; fixed digit of chelicera with two large and five small teeth vs. five large and three small teeth; anterolateral setae (al1, al2) on palp-genu in same shape and length vs. al1 shorter than al2 and with pointed tip but al2 with blunt tip. Vulgarogamasus fujisanus was described as new and compared with Eugamasus maschkeae ( Willmann, 1936) based on numerical differences of setal pairs on podonotal and opisthonotal shields, and the opisthogaster. Also, the length of the central prong of the trispinate epistome was variable. However, Micherdziński (1969) depicted the epistome of E. maschkeae with two prongs only (Fig. Abb. 378C, D; p. 540), highlighting that according to Willmann (1936) and Holzmann (1955) a short blunt central prong should be present. In the present new species, all female type specimens have a uniform shape of the epistome. Moreover, the fixed digit of the chelicera of E. maschkeae females has more teeth, including a remarkable row of seven adjacent equal teeth ( Micherdziński, 1969; Fig. Abb. 378B; p. 540).

Figures

FIGURES 1–4. Vulgarogamasus edurus sp. nov., female. 1. Podonotal shield. Scale bar = 100 µm. 2. Opisthonotal shield. Scale bar = 150 µm. 3. Opisthogastric shield. Scale bar = 100 µm. 4. Chelicera. Scale bar = 50 µm.

FIGURES 5–9. Vulgarogamasus edurus sp. nov., female. 5. Sternal shield. Scale bar = 50 µm. 6. Hypostome. Scale bar = 100 µm. 7. Anterolateral setae on palp-femur and palp-genu. Scale bar = 50 µm. 8. Epistome. Scale bar = 20 µm. 9. Chelicera. Scale bar = 50 µm.

FIGURES 10–14. Vulgarogamasus edurus sp. nov. 10. Deutonymph, podonotal shield. Scale bar = 100 µm. 11. Deutonymph, opisthonotal shield. Scale bar = 100 µm. 12. Deutonymph, chelicera. Scale bar = 50 µm. 13. Male, chelicera. Scale bar = 50 µm. 14. Male, leg II. Scale bar = 100 µm

FIGURES 15–18. Vulgarogamasus edurus sp. nov., deutonymph. 15. Sternal shield. Scale bar = 50 µm. 16. Central region of opisthogaster. Scale bar = 100 µm. 17. Hypostome. Scale bar = 50 µm. 18. Epistome. Scale bar = 20 µm.

FIGURES 19–22. Vulgarogamasus edurus sp. nov., male. 19. Hypostome. Scale bar = 50 µm. 20. Epistome. Scale bar = 20 µm. 21. Chelicera. Scale bar = 50 µm. 22. Leg II. Scale bar = 100 µm.