Cornigamasus allotritosternus, Yao & Guo & Yi & Jin, 2020

Yao, Mao-Yuan, Guo, Jian-Jun, Yi, Tian-Ci & Jin, Dao-Chao, 2020, Description of Cornigamasus allotritosternus sp. nov. (Mesostigmata: Parasitidae) from China, with an emphasis on the ontogenetic development of setae, Zootaxa 4821 (3), pp. 462-486 : 463-474

Cornigamasus allotritosternus sp. nov.

( Figures 1–64 )

Material examined. Holotype, female (slide no. 201703041701), found in cow dung, Qingyan Town (height 1103 m a.s.l., E 106°40′41.79″, N 26°20′23.18″), Guizhou Province, China, on 3 April, 2017, coll. Mao-Yuan Yao and Yan Shen. Paratypes, 13 females (slide no. 201703041702–201703041715), ten males (201703041716–201703041725), 25 deutonymphs (201703041726–201703041750), 12 protonymphs (201703041751–2017030417562), four larvae (201703041763–201703041766), one molting larva (2017030417a), one molting protonymph (2017030417b) and two molting deutonymphs (2017030417c), the data same as the holotype. All specimens are deposited in Institute of Entomology, Guizhou University , Guiyang, P. R . China ( GUGC) .

Description

Larva ( Figures 1–11 )

Dorsum ( Figure 1 ). Idiosoma very weakly sclerotized, length 335–378, width 285–342. Without discernible shields and ornamentation. Podonotal region bearing ten pairs of simple setae, smooth (j1, j3, j5, j6, z2, z4 and s6) or weakly pilose distally (j4, z5 and s4), and three pairs of poroids (idj4, gdj4, idj6) visible. Seta z5 much longer than other setae and two times longer than setae j5 and j6. Opisthonotal region bearing eight pairs of simple, smooth setae (J2, J3, Z3, J4, S3 and S4) or weakly pilose distally (J4 and Z4), and two pairs of poroids (idZ3, gdS3) visible. Lengths of dorsal setae: j1 24–27, j3 24–26, j4 29–32, j5 23–25, j6 23–25, z2 24–26, z4 26–29, z5 51–54, s4 40 –43, s6 24 –27, J2 28–30, J3 29–33, J4 28–31, J5 29–32, Z3 25–28, Z4 27–39, S3 26 –30, S4 27 –30.

Venter ( Figure 2 ). Without discernible shields. Tritosternum with a stalk-like base (length 39–45), two laciniae (length 48–60) and two subapical barbs ( Figure 3 ). Sternal area bearing three pairs of setae (st1, st2 and st3). Opisthogastric region with four pairs of setae (JV1, JV2, JV5 and ZV2), of which setae JV2 obviously longer than others, and two pairs of poroids (ivo4, ivp) visible. All setae set on opisthogastric membrane around anal opening. Setae pa and po present, po very long. Anal valves with a pair of minute euanal setae. Lengths of setae: st1 24–26, st2 25–27, st3 27–30, JV1 22–24, JV2 39–42, JV5 22–24, ZV2 17–20, pa 52–58, po 172–189.

Gnathosoma. Gnathotectum ( Figure 4 ) with three prongs, medial prong slightly shorter than lateral prongs, emerging from nude base, tips of prongs with some intraspecific variation. Fixed and movable digits of chelicera subequal in length (34–38), fixed digit with four teeth, an acicular pilus dentilis and club-shaped dorsal seta; movable digit with three teeth, base of movable digit with arthrodial brush ( Figure 5 ). Palpus length 115–142, form as in Figure 6 ; trochanter devoid of setae; femur with a club-shaped (al) and three simple setae (d1, d2 and pl); genu bearing a distally spatulate (al1) and four simple setae (d1, d2, d3 and pl). Tibia with 12 simple setae. Tarsus with 11 setae and 3-tined apotele. Subcapitulum ( Figure 7 ) length 98–116, with two pairs of simple setae (h1 length 40–42, h2 length 41–43) and 10–12 rows of denticles medially; corniculus (length 18–23), horn-shaped, reaching midpoint of palp trochanter. Salivary stylus distinct and located lateral to base of seta h2. Fringed internal malae distinct.

Legs. Leg Ⅰ ( Figures 8, 9 ) length 372–398, slenderer than legs II and III. Tarsus Ⅰ with five discernible solenidia, clavate and shorter than tactile setae. Leg II 365–382 ( Figure 10 ), leg III 369–384 ( Figure 11 ). Most tactile setae of legs simple, a few with pilose ends. Setal formulae and number of legs Ⅰ –III shown in Table 1.

Protonymph ( Figures 12–23 )

Dorsum ( Figure 12 ). Idiosoma weakly sclerotized, length 561–584, width 385–413. Podonotal and opisthonotal regions medially with a weak transverse suture not reaching lateral margins. Podonotal region with 15 pairs of setae, of which 11 pairs smooth and nearly equal in length, four pairs (j1, j4, z5 and r3) with finely pilose ends and relatively long, and five pairs of poroids visible. Setae z5 two times as long as setae j5 and j6. Opisthonotal region bearing 13 pairs of setae, which of setae J5 and Z3 with finely pilose ends, and 11 pairs of poroids visible. Lengths of dorsal setae: j1 32–36, j2 23–26, j3 28–32, j4 38–42, j5 25–29, j6 27–31, z2 24–26, z4 26–28, z5 45–48, s4 30 –34, s5 30 –32, s6 21 –24, r2 28–31, r3 45–47, r5 22–25, J1 28–31, J2 23–25, J3 24–26, J4 25–27, J5 48–51, Z1 34–36, Z2 24–26, Z3 37–40, Z4 23–25, S2 25 –27, S3 23 –26, S4 22 –26, R1 25–27.

Venter ( Figure 13 ). Tritosternum ( Figure 14 ) with slightly pilose laciniae laterally, length 105–121, base of tritosternum length 58–71. Sternal area bearing four pairs of setae (st1–st3 and st5) and two pairs of poroids. Opisthogastric region with five pairs of setae on soft cuticle (JV1, JV2, JV5, ZV1 and ZV2) and four pairs of poroids visible. Anal shield triangular and weakly sclerotized. Setae pa shorter than po. All ventral setae simple. Peritreme (49–58) short and located posterior level of coxa III. Lengths of setae: st1 24–26, st2 22–25, st3 22–24, st5 13–15, JV1 24–26, JV2 29–31, JV5 23–25, ZV1 11–13, ZV2 25–27, pa 18–21, po 32–34.

Gnathosoma. Gnathotectum ( Figure 15 ) trispinate, median triangle prong slightly wider and distally more pointed than lateral prongs. Lateral margins of tectum nude. Chelicera ( Figure 16 ) as in larva, fixed and movable digits subequal in length (86–90). Palpus ( Figure 17 ), length 175–192, with one seta (v1) on trochanter. Setation of femur, genu and tibia as in the larva. Tarsus with 15 setae and 3-tined apotele. Subcapitulum ( Figure 18 ), length 156–165, with four pairs of setae (h1, h2, h3 and pcx) and 10–12 rows of denticles. Lengths of setae: h1 50–52, h2 29–31, h3 61–64, pcx 33–35. Corniculus length 48–55, reaching anterior margin of palp trochanter.

Legs. Leg Ⅰ ( Figures 19, 20 ) 562–584, slenderer than legs II –IV. Tarsus Ⅰ with six discernible solenidia. Lengths of other legs: leg II 399–408 ( Figure 21 ), leg III 389–402 ( Figure 22 ) and leg IV 502–519 ( Figure 23 ). Most tactile setae of legs simple, a few with pilose ends, seta al2 very long on tarsus IV. Setal formulae and number of legs Ⅰ –IV shown in Table 1.

Deutonymph ( Figures 24–36 )

Dorsum ( Figure 24 ). Idiosoma well-sclerotized, length 741–874, width 507–618. Podonotal and opisthonotal shields with distinct reticulations and usually yellowish-brown alive. Posterior margin of podonotal shield convex, fitted closely with concave anterior margin of opisthonotal shield. Podonotal shield, length 440–563, width 411–436, distinctly broader than opisthonotal shield, length 199–214, width 319–342. Podonotal shield with 18 pairs of setae, of which four pairs (j1, j4, z5, r3) relatively stout with pilose ends, and nine pairs of poroids visible. Opisthonotal shield with 11 pairs of poroids visually and 12 pairs of setae, of which three pairs (Z3 and J5) relatively longer, stout and with pilose ends. The membranous cuticle bearing and three pairs of poroids and 17 pairs of setae (s2, r2, r4, r6, r6, J6, Z5–Z6, S4–S6, R1–R6), which of setae Z6 long, stout and pilose distally, the remainder setae simple. Lengths of setae on the shields: j1 35–39, j2 27–29, j3 29–34, j4 38–42, j5 27–29, j6 27–30, z1 23–26, z2 23–25, z3 24–26, z4 27–29, z5 40–42, z6 26–28, s2 24 –26, s3 11 –14, s4 28 –30, s5 28 –30, r3 41–45, r5 29–31, J1 28–30, J2 24–26, J3 24–25, J4 24–26, J5 39–42, Z1 38–42, Z2 28–29, Z3 39–42, Z4 23–25, S1 24 –26, S2 26 –28, S3 25 –29.

Venter ( Figure 25 ). Tritosternum with long laciniae ( Figure 26 ), length 105–142, base length 62–79, flanked by two pairs of presternal platelets. Sternal shield bearing four pairs of setae (st1–st4) and three pairs of poroids, length 258–292, width 159–182, strongly sclerotized and reticulated, lateral cells longer than middle cells. Sternal seta st5 off sternal shield, at level of coxae IV. Opisthogastric region with 10 pairs of setae and six pairs of poroids visible. Gland pores gv2 well-developed and with three openings. One pair of metapodal shields present at level of setae JV1 and ZV1. Anal shield reticulated and elliptical. Setae pa and po subequal in length. All ventral setae simple. Stigma at level of coxae IV or between coxae III–IV, peritreme extending to level of coxae I. Lengths of setae: st1 33–36, st2 28–30, st3 28–30, st4 24–27, st5 24–26, JV1 28–30, JV2 34–36, JV3 34–36, JV5 46–49, ZV1 18–20, ZV2 33–34, ZV3 30–32, ZV4 24–26, UR5 20–21, pa 26–28, po 28–31.

Gnathosoma. Gnathotectum ( Figure 27 ). Distal end of medial prong intraspecifically variable: round, forked or truncate, 54–65 in length, emerging from denticulate base. Fixed digit of chelicera ( Figure 28 ), length 125–135, with four teeth, pilus dentilis and dorsal seta; movable digit 128–141, with three teeth. Palpus ( Figure 29 ) length 239–266, trochanter bearing setae v1 and v2, seta v2 pilose distally and set on tubercle; femur with five pairs of setae, seta al rod-shaped, lateral end of femur with a small tubercle; genu with six pairs of setae, setae al1 and al2 spatulate distally; tibia with 14 pairs of setae; tarsus with 15 setae and 3-tined apotele. Subcapitulum ( Figure 30 ), length 216–242, width 192–225, with four pairs of setae (lengths of setae: h1 68–72, h2 38–45, h3 96–112, pcx 46–53). Corniculus (82–96), long, slender and reaching midpoint of palp femur; salivary styli run from outside bases of corniculus, beginning lateral and below base of seta h1; corniculus grooved to accommodate salivary styli. Deutosternal groove with 10–12 rows of denticles.

Legs. Leg Ⅰ ( Figures 31, 32 ) 626–770 in length. Tarsus Ⅰ with seven discernible solenidia. Length of leg II 589–623 ( Figure 33 ), leg III 551–599 ( Figure 34 ) and leg IV 714–782 ( Figures 35, 36 ). Coxa III with a small tubercle bearing seta pv. Most tactile setae simple, a few with pilose ends, setae al2 very long on tarsus IV. Setal formulae and number of leg setae shown in Table 1.

Female ( Figures 37–50 )

Dorsum ( Figure 37 ). Idiosoma length 984–1238, width 706–791. Podonotal and opisthonotal shields strongly reticulated. Podonotal shield, length 498–556, width 542–593, bearing nine pairs of poroids visually and 21 pairs of short, fine setae, excepting j1, j4, z5 and r3 brush-like. Seta r4 off shield. Posterior margin of podonotal shield and anterior margin of opisthonotal shield closely aligned, each with undulating margins. Opisthonotal shield length 439–472, width 499–564, with 13 pairs of poroids visually and 12 pairs of setae, of which three brush-like (Z1, Z3 and J5). Membranous cuticle bearing one pairs of poroids visibly and 14 pairs of setae (r4, r6, J6, Z5–Z6, S4–S6, R1–R6), which of only seta Z6 pilose distally. Lengths of dorsal setae on shields: j1 57–60, j2 23–25, j3 29–31, j4 64–68, j5 20–25, j6 20–23, z1 22–24, z2 20–23, z3 18–23, z4 22–24, z5 68–71, z6 20–22, s1 20 –23, s2 19 –23, s3 19 –23, s4 22 –25, s5 19 –24, s6 19 –23, r2 19–24, r3 96–101, r4 20–24, r5 26–30, J1 24–27, J2 25–29, J3 24–28, J4 26–30, J5 90–95, Z1 83–86, Z2 28–33, Z3 88–92, Z4 25–29, S1 21 –24, S2 27 –32, S3 25 –29.

Venter ( Figure 38 ). Tritosternum with pilose laciniae, length 131–148. Base of tritosternum, length 64–72, flanked by two or three pairs of presternal shields close to each other, of which one near to median evidently larger than other two and anterolateral shield sometimes fragmented. Sternal shield (126–137 long, 193–209 wide) reticulated, with three pairs of setae (st1–3), of which st2 slightly thicker and shorter than st1 and st3, and two pairs of poroids (iv1–iv2). Anterior margin of sternal shield slightly concave, posterior margin deeply notched. Metasternal shield clearly detached from sternal shield, bearing st4 and poroids iv3.

Genital shield (265–289 long, 272–285 wide) bearing a pair of simple epigynal setae (st5), the anterior half narrow and pointed at end and the posterior separated from the opisthogastric shield. Genital shield fused with region of opisthogastric shield at gv2 glands. Endogynium ( Figures 39, 40 ) length 183–218, width 130–154, with lateral lines forming a curtain-shaped decoration on inside of each side, base conchoidal, nearly equal to distance between bases of setae st5 (in ventral view). Opisthogastric shield gradually narrowed, fused posteriorly with small perianal plate and bearing three pairs of poroids visually and seven pairs of setae, of which JV2, JV3, JV4, ZV2 and ZV3 with slight pilose ends. Anal region with gland pores gv3 and setae pa and po. Seta JV5 brush-like, on soft cuticle. Peritreme length 472–487, extending anteriorly to level of coxa I. Lengths of ventral setae: st1 55–58, st2 46–51, st3 57–61, st4 56–59, st5 62–65, JV1 49–53, JV2 57–61, JV3 63–66, JV4 77–62, JV5 86–92, ZV1 33–36, ZV2 53–56, ZV3 43–47, ZV4 33–36, UR5 33–35, UR6 32–34, po 28–32, pa 17–19.

Gnathosoma. Gnathotectum as in figure 41, central prong smooth, length 69–73. Fixed digit of chelicera ( Figure 42 ), length 128–138, with four teeth and a pilus dentilis, movable digit length 139–153, with three teeth. Palpus ( Figure 43 ) as in deutonymph, length 245–289, distolateral palp femur with hook-like projection. Subcapitulum ( Figure 44 ) as in deutonymph, length 257–273, width 220–235; deutosternal groove with 10–12 visible rows of fine denticles. Lengths of setae: h1 73–80, h2 95–103, h3 28–32, pcx 43–47. Corniculus length 106–118.

Legs. Leg Ⅰ 884–956 ( Figures 45, 46 ), tarsus Ⅰ with seven discernible solenidia. Length of leg II 716–771 ( Figure 47 ), leg III 638–709 ( Figure 48 ), leg IV 907–963 ( Figures 49, 50 ). Coxa III with a small tubercle bearing seta pv. Femur IV with a long seta av1. Most leg tactile setae simple and a few with pilose ends. Setal formulae and number of legs setae shown in Table 1.

Male ( Figures 51–64 )

Dorsum ( Figure 51 ). Idiosoma length 949–982, width 665–698. Dorsal shield covering nearly entire dorsum, although a complete transverse suture present between podonotal and opisthonotal shields. Podonotal region with seven pairs of poroids visually and 22 pairs of setae, of which j1, j4, z5, r3 brush-like. Opisthonotal region with seven pairs of poroids visually and 23–25 pairs of setae, of which four brush-like (Z1, Z3, J5 and Z6).

Venter ( Figure 52 ). Tritosternum bearing pilose laciniae (62–76), the base of tritosternum reduced and covered by genital lamina ( Figure 53 ). Genital lamina length 97–104, width 48–56, flanked by two pairs of presternal shields, posterior shield subtriangular and obviously larger than anterior shield, which is sometimes fragmented into two shields. Sternogenital shield (length 246–281), with five pairs of setae (st1–5) and three pairs of poroids, separated from opisthogastric region by a narrow transverse suture and coalescing in region of gv2 glands. Opisthogastric region with 13 pairs of setae, of which six pairs (JV2, JV3, JV4, JV5, ZV2 and ZV3) stout and with pilose ends. Peritreme length 411–482.

Gnathosoma. Central prong of gnathotectum smooth, length 69–76 ( Figure 54 ). Fixed digit of chelicera with three teeth, movable with one tooth, spermatotreme distally fused with movable digit ( Figure 55 ). Palpus as in the female, length 246–283 ( Figure 56 ). Corniculus length 102–113. Palp chaetotaxy, corniculus and venter of gnathosoma ( Figure 57 ) similar to female. Lengths of setae: h1 76–80, h2 31–35, h3 103–107, pcx 44–47.

Legs. Leg Ⅰ 887–949 ( Figures 58, 59 ), leg II ( Figure 60 ) 704–779, leg III 622–689 ( Figure 61 ), leg IV 882–969 ( Figures 62, 63 ). Leg II stouter than others. Setae v1 and v2 on femur II modified, tubercle-shaped, their bases fused ( Figure 64 ), av1 on genu II and tibia II reduced to spur-like processes. Seta pv on a small tubercle of coxa III. Most tactile setae of legs simple, a few with pilose ends. Setal formulae and number of setae shown in Table 1.

Etymology. This species is named after the tritosternum of male, which is different in the form from the female.

Remarks. To date, eight species of Cornigamasus have been described worldwide ( Witaliński 2014). The deutonymph is known for all species except C. karachiensis . The deutonymph of C. allotritosternus sp. nov. is distinguished by having dorsal idiosomal setae j1, j4, r3, z5, Z3, J5, Z6 thick and distally pilose, while all other idiosomal setae are smooth and pointed. No other species in the genus has this combination of character states in the deutonymph.

The female is known only for C. karachiensis , C. lunaris , C. ocliferius and C. oulaensis . The adult female of C. allotritosternus sp. nov. is distinguished from C. ocliferius by having an ambulacrum on the tarsus, which is present in all other Cornigamsus species except C. ocliferius ; C. allotritosternus sp. nov. is distinguished from C. oulaensis and C. karachiensis by the form of the dorsal setae, of which eight pairs are brush-like (j1, j4, z5, r3, Z1, Z3, J5, Z6) in C. allotritosternus sp. nov. rather than all dorsal setae or 19 pairs brush-like or club-shaped and distally ornamented; C. allotritosternus sp. nov. is distinguished from C. lunaris by the shape of endogynium, which comprises lateral lines forming a curtain-shaped decoration on the inside of each side and a conchoidal base rather than a transversely situated granular band with a forward-protruding tooth on one side only.

The male is known only for C. lunaris , C. ocliferius and C. oulaensis . The males of all of these other species lack a tritosternum, while it is retained in C. allotritosternus sp. nov.. The new species further differs from the other species by the same ambulacral and dorsal setae differences observed in the females of the respective species. Further, C. allotritosternus sp. nov. differs from C. lunaris by the shape of spurs on genu II a nd tibia II, which are similar, but located close to a middle position rather than on the distal margin as in C. lunaris .

Figures

FIGURE 1. Cornigamasus allotritosternus sp. nov., larva. 1. Dorsum.

FIGURE 2. Cornigamasus allotritosternus sp. nov., larva. 2. Venter.

FIGURES 3–7. Cornigamasus allotritosternus sp. nov., larva. 3. Tritosternum; 4. Gnathotectum; 5. Chelicera; 6. Palpus; 7. Hypostome.

FIGURES 8–11. Cornigamasus allotritosternus sp. nov., larva. 8–9. Leg I; 10. Leg II; 11. Leg III.

FIGURE 12. Cornigamasus allotritosternus sp. nov., protonymph. 12. Dorsum.

FIGURE 13. Cornigamasus allotritosternus sp. nov., protonymph. 13. Venter.

FIGURES 14–18. Cornigamasus allotritosternus sp. nov., protonymph. 14. Tritosternum; 15. Gnathotectum; 16. Chelicera; 17. Palpus; 18. Hypostome.

FIGURES 19–23. Cornigamasus allotritosternus sp. nov., protonymph. 19–20. Leg I; 21. Leg II; 22. Leg III; 23. Leg IV.

FIGURE 24. Cornigamasus allotritosternus sp. nov., deutonymph. 24. Dorsum.

FIGURE 25. Cornigamasus allotritosternus sp. nov., deutonymph. 25. Venter.

FIGURES 26–30. Cornigamasus allotritosternus sp. nov., deutonymph. 26. Tritosternum; 27. Gnathotectum; 28. Chelicera; 29. Palpus; 30. Hypostome.

FIGURES 31–36. Cornigamasus allotritosternus sp. nov., deutonymph. 31–32. Leg I; 33. Leg II; 34. Leg III; 35–36. Leg IV.

FIGURE 37. Cornigamasus allotritosternus sp. nov., female. 37. Dorsum.

FIGURE 38. Cornigamasus allotritosternus sp. nov., female. 38. Venter.

FIGURES 39–40. Cornigamasus allotritosternus sp. nov., female. 39–40. Showing of endogynium.

FIGURES 41–44. Cornigamasus allotritosternus sp. nov., female. 41. Gnathotectum; 42. Chelicera; 43. Palpus; 44. Hypostome.

FIGURES 45–50. Cornigamasus allotritosternus sp. nov., female. 45–46. Leg I; 47. Leg II; 48. Leg III; 49–50. Leg IV.

FIGURE 51. Cornigamasus allotritosternus sp. nov., male. 51. Dorsum.

FIGURE 52. Cornigamasus allotritosternus sp. nov., male. 52. Venter.

FIGURES 53–57. Cornigamasus allotritosternus sp. nov., male. 53. Tritosternum; 54. Gnathotectum; 55. Chelicera; 56. Palpus; 57. Hypostome.

FIGURES 58–64. Cornigamasus allotritosternus sp. nov., male. 58–59. Leg αʹ; 60. Leg βʹ; 61. Leg γʹ; 62–63. Leg δʹ; 64. Showing of spurs on the femur II.