Tarsonemus narkelae Karmakar and Mondal

Mondal, Priyankar, Ganguly, Moumi, Karmakar, Krishna & de Moraes, Gilberto J., 2022, Two new species of Tarsonemus (Acari: Tarsonemidae) from the Indo-Gangetic plains of West Bengal, India, with brief notes on their bioecology, Journal of Natural History 55 (41 - 42), pp. 2569-2588 : 2571-2577

Tarsonemus narkelae Karmakar and Mondal sp. nov.

( Figures 1–12, 25–29)

Diagnosis

Adult of both sexes. Gnathosomal capsule subtriangular; pharynx fusiform, with thick muscular walls. Sensory cluster on tibia I complete; Setae pl” inserted anterior to solenidion ω. Female: Gnathosoma with pp as long as dgs. Anterior hood-like extension of prodorsal shield covering nearly half of gnathosoma; setae sc2 more than twice the length of v1; setae c1 slightly shorter than or subequal to c2; seta f conspicuously longer than any other opisthosomal seta. Sejugal apodeme (ap sj) conspicuous, laterally curved upward and characteristically sinuate in middle with inverted ‘w’ shape; fused coxisternites III and IV anteriorly concave and perpendicularly striate covering middle of sejugal apodeme; apodemes 4 (ap 4) inconspicuously meet with poststernal apodeme (ap po); the latter weakly bifurcated anteriorly with a diffused swollen neck immediately posterior to bifurcation. Leg I with strongly curved claw, Seta d of tibia I slightly barbed, nearly 1.5 times longer than the length of tibiotarsus I; seta v” on femur I slightly serrate; tc” twice the length of v’Ti on leg IV, both setae smooth. Male: Dorsal setae barbed except v2 and c2; setae v1 almost equal to sc 2 in length; sc1 2.5 times longer than sc2; setae c1 and c2 of a similar length, d slightly shorter than both. Metapodosomal ventral setae almost twice the length of propodosomal ventral setae. Solenidion ω tarsus I and II similar in length; femorogenu IV 1.8 times longer than wide basally; v’Ti thick, barbed, almost as long as femorogenu IV; length of claw equal to the combined length of tibia and tarsus IV.

Adult female (10 specimens measured).

Gnathosoma: subtriangular, length 22 (20–25), maximum width 23 (22–26). Setae dgs 12 (8–12) and vgs 9 (8–11), both smooth; seta pp slender, smooth 14 (12–16) long. Palpi short with 2 small subterminal setae and a pair of dentate structures apically. Pharynx fusiform, 16 (13–18) long and 6 (5–7) wide at widest level, nearly one-fourth width of gnathosomal capsule.

Idiosoma ( Figures 1, 2): length 179 (173–184), maximum width 108 (102–117) at level of c1. Dorsum: Prodorsal shield covering nearly half of gnathosoma with hood-shaped extension anteriorly and an almost straight posterior margin. Stigma located on lateral margin of prodorsal shield, slightly closer to bases of v1 than sc1; each trachea with 1 lanceoloid sclerotised post-atrial sac. Bothridial seta sc1 globose and spiny, located ventrolaterally closer to base of sc 2 than to base of v1. Dorsal plates with margins perpendicularly striate. Length of setae: v1 32 (29–33), sc1 13 (12–14), sc2 75 (73–77), c1 20 (18–21), c2 24 (22–25), d 11 (9–11), e 9 (8–10), f 18 (17–20), h 9 (8–10). All dorsal podosomal setae setiform, pointed towards end except sc1; setae d, e, f and h moderately barbed, others smooth. Distances between setae: v1–v1 22 (20–23), sc2–sc2 49 (47– 52), v1–sc2 29 (28–31), c1–c1 64 (62–66) c2–c2 95 (91–97), c1–c2 32 (30–34), d–d 28 (27– 31), f–f 16 (15–18), e–f 28 (26–28), h–h 36 (34–37). Venter: coxisternal setae 1a 8 (7–8), near middle of apodemes 1 and at level of point of fusion of apodemes 1 (ap 1) and prosternal apodeme (ap pr); 2a 10 (9–11) mediad apodemes 2 (ap 2); 3a 15 (14–17) near anterior end of apodemes 3 (ap 3); 3b 6 (6–8) located on posterior end of apodemes 4; all setae smooth. Seta 1b and 2b absent, only pits visible. Apodemes 1 conspicuous, converging posteriorly to fuse with anterior end of prosternal apodeme. Apodemes 2 long, clearly separated from prosternal apodeme. The latter conspicuous from point of fusion with apodemes 1 with a submedial node in region between apodemes 1 and apodemes 2, prominent through entire length but weakly fused with sejugal apodeme. Sejugal apodeme conspicuous, laterally curved upward and characteristically sinuate in middle with inverted ‘w’ shape. Apodemes 3 extending diagonally from anterior end of trochanter III to about longitudinal level of insertion of 3a with proximal end blunt and widened; apodemes 4 with a medial and distal node, inconspicuously meeting anterior region of poststernal apodeme from which it extends diagonally up to base of seta 3b. Poststernal apodeme conspicuous with a medial node parallel to nodes of apodemes 4, weakly bifurcate anteriorly with a diffused swollen neck immediately posterior of the bifurcation. Coxisternal plates smooth; fused coxisternal plate III and IV overlap middle of sejugal apodeme anteriorly. Tegula lobe-like, 5 (5–7) long and 10 (9–12) wide at the level of lower margin of trochanter IV. Seta ps slender 8 (7–9), weakly barbed.

Legs ( Figures 3–6): lengths (femur to tarsus): leg I 51 (48–55), leg II 46 (44–50), leg III 53 (51–55), leg IV 33 (32–36). 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- 6, leg IV: 1+1-1+1. Claw of leg I strongly hooked. Tibioarsus I with solenidion ω 7 (6–8) long, stout and clavate; seta pv” 17 (14–18) twice longer than pv’ 7 (6–9); both setae smooth and attenuated; seta pl” 8 (6–9), slender, pointed apically. Sensory cluster of tibia I complete, solenidia φ1 2 (2–3); φ2 2, stout and capitate; famulus k 4 (3–4), inserted at same level as solenidia. Seta d of tibia I 34 (26–30) long, barbed, nearly 1.5 times longer than tibiotarsus I; seta v’ slender, attenuate 12 (10–13) long. Genu I with seta l’ 15 (12–16), smooth, attenuated; v” on femur I slightly serrate, pointed towards end, 20 (18–22) long. Solenidion ω of tarsus II proximal, 5 (4–5) long, stout, capitate; seta pl” 2 (2–3), spine-like, inserted at same level as ω; seta u’ thicker and longer than u”. Seta d of tibia II 18(16–19), smooth; seta l’ of both femur and genu II stiff, smooth with pointed ends. Seta d mediad tibia III, smooth, setiform, 12 (10–13) long; both pv’ and pv” present on tarsus III; both unguinal setae present; u” slender, longer than stiff u’. Femorogenu IV 27 (25–29); tibiotarsus IV 6 (5–17). Lengths of setae of leg IV: v’F 8 (7–9), v’G 11 (10–14), v’Ti 23 (20–25) and tc” 48 (44–50); all setae smooth.

Adult male (5 specimens measured).

Gnathosoma: subtriangular, length 23 (22–26), maximum width 25 (23–26). Setae dgs 10 (8–10) and vgs 9 (7–9), both smooth; seta pp indiscernible. Palpi short with 2 small subterminal setae and a pair of dentate structures apically. Pharynx well muscled, fusiform, 17 (15–18) long and 6 (6–7) wide at widest region, about one-fourth width of gnathosomal capsule.

Idiosoma ( Figures 7, 8): length 136 (128–137), maximum width 82 (77–84). Dorsum: Prodorsal shield trapezoidal, anterior margin slightly concave. Length of setae: v1 24 (22– 26), v2 20 (19–22), sc1 69 (67–71), sc2 25 (23–26), c1 24 (22–25), c2 23 (22–25), d 20 (20–23), f 14 (12–15). Dorsal propodosomal setae setiform, pointed apically; only v2 smooth, others barbed. Only c2 smooth among dorsal hysterosomal setae, others barbed; setae c1 and d stiff and blunt ended. Distances between setae: v1–v1 14 (13–16), v2–v2 24 (22–25), v1–v2 15 (13–116), sc1–sc1 34 (32–36), sc2–sc2 41 (38–43), sc1–sc2 9 (8–10), v2–sc2 19 (17–21), c1–c1 67 (66–71), c2–c2 85 (82–87), c1–c2 28 (27–31), d–d 30 (28–32), f–f 24 (21–25). Seta c1 slightly closer to d than c2. Prodorsal plate smooth, fused dorsal plate CD with wrinkled pattern near lateral margins. Venter: coxisternal setae 1a 10 (8–10) long, posteriad apodemes 1 and below level of point of fusion of apodemes 1 and prosternal apodeme; 2a 9 (7–10), mesad apodemes 2; 3a 19 (18–21), near anterior end of apodemes 3; 3b 18 (17–20), nearly mediad apodemes 4; all setae smooth. Seta 1b and 2b absent, only pits visible. Apodemes 1 conspicuous, converging posteriorly to fuse with anterior end of prosternal apodeme. The latter conspicuous only up to junction with apodemes 2, diffused afterwards and meeting sejugal apodeme inconspicuously. Sejugal apodeme almost straight, conspicuous laterally but interrupted medially. Apodemes 3, 4, and poststernal apodeme conspicuous, connected to each other anteriorly by transversal lines, which together make sinuate lobed margin. Coxisternal plates 3 and 4 with minute longitudinal striae.

Legs ( Figures 9–12): length (femur to tarsus): leg I 48 (47–53), leg II 46 (43–48), leg III 53 (46–53), leg IV 45 (40–46). Number of setae (solenidia in parentheses) on femur, genu, tibia and tarsus: leg I: 4-4-6(2)-8(1), leg II: 3-3-4-7(1), leg III: 1-3-4-6, leg IV: 1-3-1(1)+3. Claw of leg I strongly hooked. Solenidion ω of tarsus I 6 (5–6), stout, clavate; seta pv’ 11 (9–13) nearly as long as pv” 12 (10–14); both setae smooth and setiform; seta pl” 4 (3–6), slender and pointed apically. Sensory cluster of tibia I complete, solenidia φ1 3 and φ2 3, capitate; famulus k 3 (3–4) rod-like, inserted at same level as solenidia. Seta d of tibia I 24 (20–25), smooth; seta v’ 7 (6–8) slender, smooth. Solenidion ω of tarsus II proximal, 6 (6–7) long, stout, widened medially; pl” 2, thorn-like, inserted at same level as ω; seta u’ stiff, as long as u”, both spinose. Seta l’ on genu I 10 (8–11), smooth, tapering towards end; seta v” on femur I 13 (11–15), setiform and smooth. Seta d of tibia II 15 (13–16), smooth. seta l’ on both femur and genu II smooth, stiff and pointed apically. Seta d 15 (13–17), smooth, setiform mediad tibia III; both pv’ and pv” present on tarsus III; both unguinal setae present; u” slender, slightly longer than stiff u’. Seta v’ of trochanter IV 15 (13–16), smooth; femorogenu IV, 35 (33–37) long and 19 (18–20) wide at v’ F level, without flange, inner margin moderately concave and outer margin slightly convex at distal part. Setae v’ F 9 (8– 11), smooth; v’ G 20 (18–22), l” G 21 (18–23) smooth; tibia IV 7 (7–9), solenidion φ 8 (7–8), bacilliform, v’ Ti 38 (35–40), barbed; tarsus IV 3 (2–3), tc” 7 (6–7), pv” 6 (5–7) and u’ 6 (5–7). Claw on leg IV well developed, stout, unciform, 10 (8–11) long, 5 (5–7) wide basally.

Differential diagnosis. This new species is most similar to Tarsonemus confusus Ewing, 1939 , T. caucasicus Sharonov and Mitrofanov, 1986 and T. vasoviensis Kaliszewski, 1993 in having the sejugal apodeme laterally curved upwards and characteristically sinuate in the middle with inverted ‘W’ shape and opisthosomal setae d, e, f and h being coarse in the adult female. However, females of T. narkelae Karmakar and Mondal sp. nov. differ from those of T. confusus and T. vasoviensis by their smooth dorsal and ventral plates (compared to delicate granulations in T. confusus and T. vasoviensis ); posterior margin of plate C convex (compared to concave margin in T. confusus and T. vasoviensis ); poststeranal apodeme with a medial node and weakly bifurcated anteriorly (poststernal apodeme without node and conspicuously bifurcated anteriorly in both T. confusus and T. vasoviensis ); apodemes 4 with medial nodes and weakly fused with poststernal apodeme (apodemes 4 without node and conspicuously fused with poststernal apodeme in both T. confusus and T. vasoviensis ). Females of the new species differ from T. confusus also by longer dorsal setae sc2 (73–77 vs 60), f (17–20 vs 12); shorter ps (7–10 vs 20); and prosternal apodeme conspicuous beyond the level of apodemes 2 (diffused beyond apodemes 2 in T. confusus ). They differ from T. vasoviensis also by smooth dorsal and ventral plates (compared to delicately granulated in T. vasoviensis ); longer dorsal setae sc2 (73–77 vs 64–71); shorter dorsal setae h (8–10 vs 15); and shorter ventral setae 1a (7–8 vs 12–13), 3b (6–8 vs 11–13). Females of T. narkelae sp. nov. differ from those of T. caucasicus by both prosternal and poststernal apodeme entire (vs prosternal apodeme diffused below the level of 1a and poststernal apodeme submedially interrupted in T. caucasicus ); apodemes 4 joined with poststernal apodeme anteriorly at the diffused swollen neck immediately posterior to bifurcation (vs apodemes 4 conspicuously fused with poststernal apodeme near middle of the anterior half in T. caucasicus ); and tibiotarsus I with pl” (absent in T. caucasicus ). Males differ from those of T. caucasicus by dorsal seta v2 slender and smooth (vs v2 sparsely barbed and stiff in T. caucasicus ); prosternal apodeme diffused after level of apodemes 2 (vs prosternal apodeme conspicuous after apodemes 2 in T. caucasicus ); and ventral seta 3a nearly as long as 3b (vs 3a nearly twice the length of 3b in T. caucasicus ). Female of this new species also closely resemble T. lanceatus Lin and Zhang, 1995 with respect to the shape of the sejugal apodeme and dorsal seta f twice the length of h. However, the new species differs by conspicuous prosternal apodeme beyond the level of apodemes 2 (prosternal apodeme diffused after apodemes 2 in T. lanceatus ), apodemes 4 uninterrupted in middle (compared to apodemes 4 interrupted in T. lanceatus ) and poststernal apodeme weakly bifurcated anteriorly (compared to absence of such bifurcation in T. lanceatus ). Males of T. narkelae sp. nov. differ from those of T. lanceatus by sc1 barbed and longer than the length of prodorsum (compared to sc1 smooth and shorter than the length of prodorsum in T. lanceatus ); seta v1, sc2 barbed and c2 smooth (compared to smooth v1 and sc2 but barbed c 2 in T. lanceatus ). Females of this new species also resemble those of T. neotalpae Delfinado, 1976 , with respect to the poststernal apodeme bifurcated anteriorly with a broad cellular neck immediately behind the bifurcation, but differ in the shape of the sejugal apodeme and sclerotisation of the prosternal apodeme.

Type material

Holotype female, male ( Acarol.lab/BCKV/35001-02/2020 ) (submitted to NZC, Zoological Survey of India, Kolkata); 8 paratype females and 5 paratype males (Acarol. lab/BCKV/35003-8/2020), from leaves of Cocos nucifera Mondouri (22.9363o N 88.5086o E) and Jaguli (22°55 ʹ 46”N, 88°32 ʹ 57”E), State of West Bengal, 1 February 2020, P. Mondal and K. Karmakar. 5 paratype females and 4 paratype males (Acarol.lab/BCKV/35008-12/2020) from same host, Kalyani (22.9877o N 88.4572o E), State of West Bengal, 5 February 2020, P. Mondal.

Etymology

The specific epithet narkelae is derived from the Bengali word ‘ narkel ’, which refers to the coconut plant from which this species was first collected.

Remarks

Tarsonemus narkelae Karmakar and Mondal sp. nov. is an interesting tarsonemid mite species which was found to inhabit the clefts of coconut leaf blades, specifically below the waxy filaments secreted by the rugose spiralling whitefly (RSW: Aleurodicus rugioparculatus ). Microscopic observations revealed their colony with all stages from egg to adult living in the longitudinal clefts created by infolding of leaf lamina roofed by waxy material secreted by RSW ( Figure 29). They were also observed to feed on fungal (sooty mould) hyphae and spores grown over the excreted honeydew. We believe they use the waxy filaments as a roof to protect themselves from dehydration, and the microclimate beneath this shelter is favourable for their multiplication. However, any phoretic or mutualistic relationship between T. narkelae sp. nov. and RSW was not observed during the present study, and we suspect that this new species might also be associated with other waxsecreting and sooty-mould-growing homopterans.