Ceratotarsonemus bengalicus Karmakar and Kayal, 2022

Kayal, Sandipan, Mondal, Priyankar & Karmakar, Krishna, 2022, The first record of Ceratotarsonemus (Acari: Tarsonemidae) from the Oriental region with description of a new species from West Bengal, India, Zootaxa 5182 (3), pp. 238-246 : 243-245

Ceratotarsonemus bengalicus Karmakar and Kayal sp. nov.

( Figs. 1–4 )

Diagnosis. Prodorsal shield of adult female distinctly ornamented with a series of irregular striations medially and several cells compactly arranged in semi-ovate area posteriorly; tergite C with a pair of anterodorsal sickle-shaped sclerotizations and a trapezoidal reticulated area with four rows of irregular quadrangular cells; sejugal apodeme strongly developed, medially with convex lobe and uninterrupted throughout; scapular setae sc2 1.2 times longer than v1. Ventrally coxisternal setae 2a nearly twice longer than 1a, and coxisternal setae 3a more than 2.5 times longer than 3b.

Description. FEMALE (holotype, range for 2 paratypes in parentheses). Gnathosoma ( Figs. 1A , 2B ): Subquadrate in shape, dorsally globose, ventrally flattened, nearly as long as wide, length 21 (19–22), maximum width 24 (22–26). Seta dgs 11 (10–12) long, sparsely barbed; vgs 7 (6–9), smooth; seta pp not observed. Palpi directed anteriorly, parallel, slightly elongate, each with two minute setae and inconspicuous tooth-like processes apically. Cheliceral stylets short, protracted between palpi at rest, coupled to distinct basal levers. Pharynx muscular, fusiform, and 12 (12–15) long, nearly half as long as of gnathosomal length, and 6 (6–8) wide at widest level, nearly one fourth the width of gnathosoma.

Idiosoma ( Figs. 1B , 2B ): Length 174 (171–182), maximum width at level of setae c1 115 (113–122). Dorsum: Prodorsal shield anteriorly hood-like, covering basal one-third of gnathosoma, striated anteriorly and posterolaterally, medially ornamented with a series of irregular striations posteriorly followed by few cells compactly arranged in semi-ovate area. Tergite C ornamented with a pair of sickle like sclerotizations anterodorsally between bases of setae c2 followed by trapezoidal medial area with four rows of irregular quadrangular cells. Tergite C, D and E striated along the posterior margins. Stigma located on lateral notch of prodorsal shield, slightly closer to bases of setae v1 than to sc1. Bothridial seta sc1 globose and spinose, located ventrolaterally, covered by prodorsal shield nearly equidistant from the base of sc 2 and v1. Length of setae: v1 67 (65–70), sc1 17 (15–18), sc2 82 (80–85), c1 88 (86–92), c2 66 (64–68), d 85 (82–86), e 72 (70–74), f 43 (40–44), h 42 (41–44). All dorsal setae coarsely barbed. Distances between setae: v1–v1 30 (28–31), sc2–sc2 60 (58–62), v1–sc2 20 (18–21), c1–c1 67 (64–70) c2–c2 79 (76–82), c1–c2 25 (23–27), d–d 51 (48–53), f–f 12 (10–13), e–f 17 (15–18), h–h 21 (19–23). Venter: coxisternal setae 1a 7 (6–8), situated posterior to junction of apodemes 1 with prosternal apodeme; setae 2a 12 (10–13) nearly mediad apodemes 2; setae 3a 13 (11–14) slightly anterior to proximal ends of apodemes 3; 3b 5 (4–6) located at distal end of apodemes 4; setae ps slender 13 (11–14), barbed; all other ventral setae smooth and pointed.Apodemes 1 conspicuous, converging posteriorly, prominently fused with anterior end of prosternal apodeme. Apodemes 2 proximally diffused and inconspicuously connected to prosternal apodeme. Prosternal apodeme conspicuous through most of its length; diffusedly joined posteriorly with sejugal apodeme. Sejugal apodeme strongly developed, entire, medially with a convex lobe-like extension. Apodemes 3 situated posterior to transverse level of setae 3a, stretching diagonally, slightly curved and extending to anterior end of trochanters III; inner ends of apodemes 4 fused with poststernal apodeme and their outer ends diffused before reaching bases of setae 3b. Poststernal apodeme mostly conspicuous, its anterior end bifurcated and diffused. Tegula much wider than long, tegular margin slightly convex medially and lateral parts with two small angular projections on either side, 4 (3–4) long and 19 (18–20) wide at the level of posterior margin of trochanters IV.

Legs ( Fig. 3A–D ): Lengths (base of femur to apex of tarsus): leg I 42 (40–47), leg II 43 (40–46), leg III 52 (50– 55), leg IV 30 (27–33). Number of setae (solenidia in parentheses) on femur, genu, tibia and tarsus, respectively: leg I: 3-4-6(1φ) + 7(1ω); leg II: 3-3-4-4 (1ω); leg III: 1+1-4-4; leg IV:1+1-1+1.Tibiotarsus I with solenidion ω 4 (3–4) long, stout and clavate; pv” 9 (7–10), barbed; pv’ 21 (20–23), smooth and 2.5 times longer than pv”; tc’ 17 (16–19); tc” 17 (15–18); both smooth. Sensory cluster of tibia I incomplete, solenidion φ1 2, clavate; famulus k 3 (2–3), inserted slightly distal to solenidion φ1. Seta d of tibia I 38 (36–40) long, sparsely barbed, nearly two times longer than tibiotarsus I; seta s of tarsus I 2 (2–3) long, clavate. Seta l” of genu I 12 (11–13), thickened and sparsely barbed, l’ of genu I 6 (5–8), smooth; on femur I, seta l’ 8 (6–8), barbed, d 6 (5–7), smooth, and v” 5 (15–18), - smooth. Claw on leg I distally curved, 5 (5–7) long. Solenidion ω of tarsus II proximal, 5 (4–5) long, clavate and medially widened; tc’ 15 (13–16) nearly 1.5 times longer than tc’ 11 (9–12), both sparsely barbed; pv’ 8 (7–9), barbed. Seta d of tibia II 20 (19–22) long, sparsely barbed. Setae l’ of genu II 21 (20–23) barbed. Seta v” on femur II 14 (11–14) long, sparsely barbed; d 7 (6–8) long, sparsely barbed. Seta u’ present both on tarsi II and III 3 (3–4) long, thickened on tarsi II and thin spine-like on tarsi III. Seta tc” of tarsus III 18 (16–19) long, slightly longer than tc’ 14 (13–15), both sparsely barbed. Femorogenu IV 22(20–24); tibiotarsus IV 8(7–9); lengths of setae: v’ F 8(7–9), v’ G 13 (12–13), v’ Ti 21 (20–22) and tc” 28 (26–29); v’ Ti thickened and serrate.

MALE and LARVA. Unknown.

Type material. Holotype female (Acarol.lab/BCKV/BD22/2021) (submitted to NZC, Zoological Survey of India, Kolkata); 2 paratype females from leaves of Citrus reticulata (Rutaceae) , INDIA, West Bengal, Kalimpong, Rishikhola (27°09'47"N, 88°38'57"E), 22 December, 2021, coll. Sandipan Kayal.

Etymology. The species name bengalicus is derived from the type locality, West Bengal.

Differential diagnosis. Ceratotarsonemus bengalicus sp. nov. is unique in the genus because of having the prodorsal shield with medial irregular striation, several cells posterior to them arranged in semi-ovate area, and the medial part of sejugal apodeme convex posteriorly. Among previously known species of the genus, C. bengalicus sp. nov. is closest to C. amazonicus in sharing the following characters: tergite C has uneven reticulation consisting of four rows of irregular cells, setae c2 and e are long, setae c1 are longer than c2, apodemes 1 are conspicuous and joined to the anterior end of prosternal apodeme, the poststernal apodeme is bifurcate anteriorly, and tibiotarsus of leg IV is about 8 long. The new species differs from C. amazonicus in having the following features: the medial part of tegular margin is convex and lateral parts are with two small angular projections on either side (vs. tegular margin concave in C. amazonicus ); scapular setae sc2 are about 1.2 times longer than setae v1 (vs. setae sc2 nearly twice longer than v1); setae h are considerably longer (41–44 vs. 23–26); coxisternal setae 2a are twice longer than 1a (vs. 1a and 2a subequal), setae 3a are over than 2.5 times longer than 3b (vs. 3a and 3b nearly equal in length); apodemes 3 are diagonally stretched from the anterior end of trochanters III and slightly curved (vs. wavy and median ends slightly bent posterior); on legs I, tarsal solenidion ω is shorter (3–4 vs. 6–7), famulus k is shorter (2–3 vs. 5); on legs II, tibial seta d is considerably longer (19–22 vs. 12–13).

Key to Ceratotarsonemus species of the world

(updated from Ochoa et al. 1997; Rezende et al. 2018)

1. Setae d, e and f coarsely barbed and elongated; tergite C partially reticulated...................................... 2

– Setae d, e and f distinctly leaf-shaped; tergite C smooth................................... C. absurdus ( Suski, 1971)

2. Setae d longer than e, both prodorsal shield and tergite C ornamented........................................... 3

– Setae d shorter than e, only tergite C ornamented......................................... C. scitus De Leon, 1956

3. Tergite C uniformly reticulated, presenting three transverse rows of hexagonal and one row of pentagonal cells............................................................................... C. hexagonalis Ochoa and Walter, 1997

– Tergite C non-uniformly reticulated, posterior margin concave with irregular rows of cells........................... 4

4. Tergite C with two rows of cells, setae c2 and e short (~ 40 and 60 μm, respectively)....... C. alas Ochoa and Vargas, 1997

– Tergite C with 4 rows of cells, setae c2 and e long (~ 65 and 80 μm, respectively).................................. 5

5. Prodorsal shield with posterior hexagonal reticulation pattern, sejugal apodeme medially straight.................................................................................. C. amazonicus Rezende, Lofego and Ochoa, 2018

– Prodorsal shield with medial irregular striation and with posterior cells forming a semi-ovate area, medial part of sejugal apodeme convex posteriorly........................................................... C. bengalicus sp. nov.

Figures

FIGURE 1. Ceratotarsonemus bengalicus sp. nov., dorsal view of female. A—gnathosoma, B—idiosoma.

FIGURE 2. Ceratotarsonemus bengalicus sp. nov., ventral view of female. A—gnathosoma, B—idiosoma.

FIGURE 3. Ceratotarsonemus bengalicus sp. nov., female, dorsal view of legs (right side). A—leg I, B—leg II, C—leg III, D—leg IV.

FIGURE 4. Ceratotarsonemus bengalicus sp. nov., female.A—dorsal view, B—ventral view, C—dorsal view of propodosoma, D—ventral view of anterior part of hysterosoma.