Bongotarsonemus unicornus, Mondal & Karmakar, 2021

Mondal, Priyankar & Karmakar, Krishna, 2021, A new genus Bongotarsonemus with two new species of tarsonemid (Acari: Heterostigmata) mites discovered from the Himalayan forests of West Bengal, India, Zootaxa 5072 (6), pp. 575-591 : 580-585

Bongotarsonemus unicornus sp. nov.

( Figs. 2–13 ; 20–27 )

Diagnosis. Female: Both prodorsal stae v1 and sc2 each set on a prominent tubercle; spear shaped anterior prodorsal horn between the base of setal pair v1; median raised section of prodorsum with a pair of sclerotized ridges converging anteriorly to meet near base of prodorsal horn. Seta v1 nearly as long as sc2; c1 nearly as long as c2; d–h of subequal length. Tarsus I with seta tc’’ nearly twice the length of tc’ and tarsus III with tc’ approaching the length of tc’’. Tarsus II with solenidion ω stout, clavate and slightly longer than pl’’. Seta tc’’ on tarsus IV nearly 1.5 times the length of v’ Ti.

Adult female (8 specimens measured).

Gnathosoma: subtriangular, well sclerotized, length 26 (25–29), maximum width 30 (28–32). Seta dgs 12 (9– 13), sparsely barbed and vgs 6 (6–8), smooth; seta pp indiscernible. Palpus short with 2 small subterminal setae and two dentate structures apically. Pharynx well musculated, fusiform, 16 (15–18) long, two thirds the length of gnathosoma and 5 (5–6) wide at widest level, about one fifth width of gnathosomal capsule. Gnathosoma surface faintly punctate dorsally and ventrally.

Idiosoma ( Figs. 2, 3 ): length 184 (180–193), maximum width 118 (113–122) at level of c1. Dorsum: Prodorsal shield covering entire gnathosoma with hood-shaped extension anteriorly and nearly straight posterior margin. Stigma located on lateral margin of prodorsal shield, slightly closer to bases of sc1 than v1. Bothridial seta sc1 globose and spiny, located ventrolaterally, closer to base of sc 2 than to base of v1. Setae v2 vestigial, only pits are visible. setae v1 set on prominent tubercles which conspicuously extend posteriorly to fuse with tubercles of setae sc2 delimiting a medially raised section of prodorsum. Anterior prodorsal horn spear-shaped, 5 (5–7) long, between bases of v1. Prodorsal shield with a pair of sclerotized ridges medially which converge anteriorly to meet near base of anterior horn. Dorsal plates coarsely punctate and margins perpendicularly striate. Length of setae: v1 22 (20–24), sc1 13 (12–14), sc2 21 (20–24), c1 14 (13–16), c2 13 (10–14), d 9 (8–11), e 9 (8–10), f 9 (8–10), h 8 (7–10). All dorsal setae coarsely barbed; setae sc2, d and e blunt ended, others narrowly pointed apically. Distances between setae: v1–v1 18 (16–22), sc2–sc2 46 (42–47), v1–sc2 49 (45–51), c1–c1 43 (41–46) c2–c2 113 (109–116), c1–c2 38 (36–42), d–d 30 (28–32), f–f 13 (12–16), e–f 21 (19–22), h–h 33 (31–36). Venter: coxisternal setae 1a 6 (5–7), near middle of apodemes 1 and at level of point of fusion of apodemes 1 and prosternal apodeme; 2a 10 (8–10) mediad apodemes 2; 3a 9 (7–10) near anterior end of apodemes 3; 3b 6 (5–7) located at distal end of apodemes 4; all ventral setae smooth.Apodemes 1 conspicuous, converging posteriorly, forming a ‘V’ shape but not prominently fused with anterior end of prosternal apodeme. Apodemes 2 long, diffusely meet prosternal apodeme medially. Prosternal apodeme inconspicuous through most of its length, only sclerotized as a small fragment mediad the line of fusion of coxisternal plates I of both sides; diffusely meet with apodemes 1 anteriorly, split in a pair of diffused branches before meeting apodemes 2 medially and sejugal apodeme posteriorly. The latter strongly developed, laterally curved and widely separated medially. Apodemes 3 extending diagonally from anterior end of trochanter III to about longitudinal level of insertion of 3a with proximal end diffused and widened; apodemes 4 with a medial and distal node, inconspicuously meet the anterior region of poststernal apodeme from which it extends diagonally up to base of seta 3b. Poststernal apodeme mostly conspicuous with a pair of medial nodes posteriad junction with apodemes 4; weakly bifurcate anteriorly with a prominent swollen neck immediately behind the bifurcation. Coxisternal plates coarsely punctate; anterior margin of fused coxisternal plates III and IV overlap posterior part of prosternal apodeme and entire sejugal apodeme anteriorly. Tegula tongue shaped, 16 (13–16) long and 13 (11–14) wide at the level of lower margin of trochanter IV. Seta ps slender 7 (6–9), smooth.

Legs ( Figs. 4–7 ): lengths (base of femur to apex of tarsus): leg I 46 (42–49), leg II 47 (43–50), leg III 62 (59– 66), leg IV 45 (41–48). Number of setae (solenidia in parentheses) on femur, genu, tibia and tarsus, respectively: leg I: 4-4-6(2)+8(1), leg II: 3-3-4-7(1), leg III: 1+3-4-5, leg IV: 1+1-1+1. Tibiotarsus I with solenidion ω 3 (3–4) long, stout and clavate; pv’’ 12 (11–14), slightly longer than pv’ 9 (8–10); tc’’ 19 (17–21) nearly twice longer than tc’ 9 (9–11). Sensory cluster of tibia I complete, solenidion φ1 3, clavate; solenidion φ2 2, stout, capitate; famulus k 3 (3–4), inserted at same level. Seta d of tibia I 37 (34–39) long, sparsely barbed, more than 1.5 times longer than the length of tibiotarsus I; seta s of tarsus I 5 (4–6) long, stout, spine like. Seta l’ on genu I 9 (8–11), barbed; l’ on femur I 15 (13–17), plumose and v’’ 17 (15–18), attenuated and sparsely barbed. Claw on leg I fish-hook shaped 7 (6–8) long.Solenidion ω of tarsus II proximal, 3 (3–4) long, stout, clavate; seta pl” spine like, 2 long, inserted at the same level with ω; tc’’ 22 (21–24) nearly twice longer than tc’ 12 (10–13), both sparsely barbed. Seta d of tibia II 7(6–9) long, smooth. Setae l’ on both femur and genu II somewhat thickened and sparsely barbed. Both u’ and u’’ present on tarsi II and III; u’ 5 (4–5) long stout, spine like; u’’ setiform; pv’’ absent from tarsus III; tc’’ 17 (16–18) slightly longer than tc’ 14 (13–15), both sparsely barbed.. Femorogenu IV 31 (28–32); tibiotarsus IV 14 (13–16). Lengths of setae of leg IV: v’ F 10 (8–11), v’ G 17 (15–19), v’ Ti 28 (26–32) and tc” 41 (39–47); v’ Ti thickened and serrate.

Adult male (6 specimens measured).

Gnathosoma: subtriangular, length 27 (25–30), maximum width 26 (24–28). Setae dgs 14 (12–14), sparsely barbed and vgs 10 (8–11), smooth; seta pp indiscernible. Palpus short with 2 small subterminal setae and two dentate structures apically. Pharynx similarly developed as in female, fusiform, 17 (16–18) long, nearly two thirds the length of gnathosoma and 6 (5–6) wide at widest region, near about one fourth the width of gnathosomal capsule. Dorsal apodeme prominently visible with two internal sclerotized ridge like structures converging basally. Gnathosoma faintly punctate both dorsally and ventrally.

Idiosoma ( Figs.8, 9 ): length 128 (120–133), maximum width 87 (81–90). Dorsum: Prodorsal shield trapezoidal, anterior margin nearly straight. Length of setae: v1 32 (28–34), v2 12 (11–14), sc1 27 (25–30), sc2 31 (29–33), c1 15 (14–16), c2 34 (32–37), d 16 (16–18), f 12 (9–13). Dorsal setae v1, v2, c2, f setiform, pointed apically; others thickened, blunt ended; all setae coarsely barbed. Distances between setae: v1–v1 15 (13–16), v2–v2 20 (20–24), v1– v2 12 (11–15), sc1–sc1 36 (34–38), sc2–sc2 51 (48–54), sc1–sc2 13 (13–16), c1–c1 70 (68–74), c 2 –c 2 84 (82–87), c1–c2 32 (30–34), d–d 29 (28–32), f–f 20 (18–24). Seta c1 closer to d than c2. Dorsal plates faintly punctate. Venter: coxisternal setae 1a 5 (4–6) long, posteriad apodemes 1 and slightly below the level of point of fusion of apodemes 1 and prosternal apodeme; 2a 9 (8–10) mediad apodemes 2, on upper half of coxisternal plates II; 3a 21 (19–23), at anterior end of apodemes 3; 3b 10 (8–10), mediad basal half of apodemes 4; all setae smooth. Apodemes 1 conspicuous, converging posteriorly to fuse with anterior end of prosternal apodeme forming a ‘Y’ shape.Apodemes 2 conspicuous, bent downwards proximally but not fused with prosternal apodeme. The latter straight, diffused medially at the level of apodemes 2, again continue prominently to fuse with sejugal apodeme. Sejugal apodeme conspicuous and characteristically indented medially at the junction with prosternal apodeme. Apodemes 3, 4, and poststernal apodeme conspicuous, connected to each other anteriorly by transversal lines, which together make sinuate lobbed margin anteriorly. Poststernal apodeme split in two at upper margin of trochanter IV giving rise to apodemes 5. Coxisternal plates minutely punctate. Genital capsule heart-shaped, slightly longer than wide, anterior half punctate dorsally; seta h (1–2), minute, located dorsolaterally on posterior flap; accessory shafts swollen distally; aedeagus extended beyond posterior margin of genital flap with swollen distal end.

Legs ( Figs. 10–13 ): length (base of femur to apex of tarsus): leg I 54 (52–60), leg II 54 (51–58), leg III 52 (50–57), leg IV 37 (34–41). Number of setae (solenidia in parentheses) on femur, genu, tibia and tarsus: leg I: 4-4- 6(2)-10(1), leg II: 3-3-4-7(1), leg III: 1-3-4-5, leg IV: 1-3-1(1) -3. Solenidion ω of tarsus I 3 (3–4), stout, clavate. Sensory cluster of tibia I complete, solenidion φ1 3, clavate; solenidion φ2 3, capitate; famulus k 3 (3–4) rod like, inserted at same level. Seta d of tibia I 29 (26–31), sparsely barbed; tarsus I with ft’ 2 and ft’’ 3 long, smooth. Seta l’ on femur I 12 (10–13), thickened and plumose; v’’ smooth, 12 (10–14) long. Claw on leg I fish-hook shaped, as long as that of female. Solenidion ω of tarsus II proximal, 12 (11–14) long, stout, rod like, approaching length of tarsus; pl” stout, baciliform, 12 (10–13) long, blunt apically; tc’’ 31 (29–33) nearly twice longer than tc’ 14 (13–16), both sparsely barbed. Seta d of tibia II 13 (11–14), smooth. Setae l’ on genu and femur II somewhat thickened and sparsely barbed. Seta v’ of trochanter IV 12 (10-–13), serrate; femorogenu IV, 28 (25–30) long and 14 (12–15) wide at v’ F level, without flange, posterior margin convex and anterior margin slightly concave at distal half. Setae v’ F 5 (4–6), smooth; v’ G 18 (16–21), serrate; l” G 10 (9–12) smooth; tibia IV 5 (5–7), solenidion φ 23 (20–25), bacilliform, arched anteriorly; v’ Ti 29 (27–32), serrate; tarsus IV 4 (3–5), tc” 6 (5–7), pv” 6 (6–7) and u’ 6 (6–7). Claw well developed, stout, unciform, 9 (8–12) long, 4 (4–5) wide basally.

Larva. Unknown.

Type material. Holotype female (Acarol.lab/ BCKV/31018 /2021) (submitted to NZC, Zoological Survey of India, Kolkata); 8 paratype females and 7 paratype males (Acarol.lab/ BCKV/31019-24 /2020), from leaves of Prunus avium Rock Garden, Darjeeling (27°01’32”N; 88°14’16”E), State of West Bengal, 12/II/2020, coll. P. Mondal.

Etymology. The species name unicornus is derived from two Latin words viz. ‘ uni ’ meaning one and ‘ cornu ’ meaning hornlike projection referring to single sclerotized anterior prodorsal horn characteristic of the females of this species.

Remarks. Bongotarsonemus unicornus sp. nov. was collected from epiphytic fungal colonies on the leaves of Sweet Cherry, Prunus avium L. ( Rosaceae ). Direct feeding on fungus was not observed but the fungal spores were visible clinging to dorsal and ventral sclerites of the slide mounted specimens. The fungus is identified as a species of Fusicladium ( Venturiaceae : Ascomycota). This is the first record of any tarsonemid mite associated with Cherry trees in India.

Figures

FIGURES 2–3. Bongotarsonemus unicornus n. sp., (female). 2. Dorsal surface, 3. Ventral surface.

FIGURES 4–7. Bongotarsonemus unicornus n. sp., (female legs). 4.—leg I, 5.—leg II, 6.—leg III, 7. —leg IV.

FIGURES 8–9. Bongotarsonemus unicornus n. sp., (male). 8. Dorsal surface, 9. Ventral surface.

FIGURES 10–13. Bongotarsonemus unicornus n. sp., (male legs). 10.—leg I, 11.—leg II, 12.—leg III, 13. —leg IV.

FIGURES 20–31. Bongotarsonemus spp., 20–27. Bongotarsonemus unicornus n. sp., 20.—Female dorsal surface, 21.—Female ventral surface, 22.—Female legs III & IV, 23.—Female leg I with claw, 24.—Female legs I & II, 25.—Male dorsal surface, 26.—Male ventral surface, 27.—Male leg IV with claws and solinidia.