Thyreophagus cracentiseta, Barbosa, Marina Ferraz De Camargo, Oconnor, Barry M. & Moraes, Gilberto José De, 2016

Barbosa, Marina Ferraz De Camargo, Oconnor, Barry M. & Moraes, Gilberto José De, 2016, A new species of Thyreophagus (Acari: Acaridae) from Brazil, with notes on species associated with stored food and human habitats and a key to species of this genus, Zootaxa 4088 (2), pp. 279-291 : 280-284

Thyreophagus cracentiseta n. sp.

( Figs. 1–5 )

Diagnosis. Females and homeomorphic males with tarsi III bearing 7 apical spine-like setae [1 dorso-apical and 6 ventral (4 apical, 1 subapical and 1 median)]; prodorsal sclerite ornamented with broken striae on most of its extent, with slightly longer sections near posterior margin, punctate near anterior margin and over rounded anterolateral extensions; dorsal setae cp, e2, h2 and h3 smooth, filiform and slender; ro and ex slightly longer and thicker. Grandjean´s organ anteriorly expanded into membranous finger-like extensions. Base of spermathecal sclerite arched.

Description. FEMALE ( Figs. 1–4 ; n= 6). Dorsum ( Figures 1 A; 2A–2B): Idiosoma elongate, 485 (460–515) long, 195 (170–220) wide at coxa III level; cuticle smooth. Prodorsal sclerite 84 (78–87) long and 75 (68–78) wide at anterior margins, with lateral incisions; ornamented with broken striae on most of its extent, with sections slightly longer near posterior margin and punctate near anterior margin and over rounded anterolateral extensions. Grandjean´s organ anteriorly expanded in 9–10 membranous finger-like extensions; supracoxal seta (elc I) smooth and arched, 16 (12–19) long. Dorsal idiosomal setae smooth, filiform and slender, except rostral (ro) and exobothridial (ex), setiform, thicker than other dorsal setae, tapering from base to tip). Setal lengths: ro 29 (24–36), ex 53 (43–56), cp 31 (23–38), d2 26 (21–32), e2 35 (31–40), h1 24 (21–27) and h2 37 (32–47). Oil gland slightly anteriad of setal base e2.

Venter ( Figures 1 B; 2C): Ventral surface with 4 pairs of coxal setae (1a, 3a, 4a and 4b) and 1 pair of genital setae. Genital region between legs III and IV; genital valves shaped as an inverted V; epigynal apodeme welldeveloped. Anal opening on posterior margin of idiosoma, surrounded by h3 31 (24–38) long and p1 42 (41–44).

Reproductive apparatus ( Figs. 2 D; 3): Copulatory opening, 6 (5–6) in diameter located near the posterior region of opisthosoma. Spermathecal duct, slender tube 60 (51–62) long and uniformly 1 (1–2) wide leading from copulatory opening to spermatheca. Spermatheca, composed of sclerotized, arched base, 15 (13–19) wide, and elliptical vesicle where sperm is stored. Ovaries, where fertilization taking place, paired and connected to sclerotized structure of spermatheca by efferent ducts. Oviducts trident-shaped near ovaries and continuing as thick tube. Considering reduced diameter of visible part of oviducts, especially tube, it seeming that fertilized egg cells rather than developed eggs move through oviducts to uterus. Uterus and final portion of oviduct indistinguishable.

Gnathosoma ( Fig. 2 E, F): Chelicera chelate, 79 (72–83), fixed digit 23 (19–27), with 3 teeth in addition to apical tooth; movable digit 25 (23–27) long, with 2 teeth in addition to apical tooth; cheliceral seta (cha) spine-like, 3 (2–4) long. Subcapitular seta (subc) 22 (18-26) long, palp tibial seta spine-like; lateral palp tibial seta setiform; dorsal palp tarsal seta setiform and terminal palp tarsal solenidion minute; seta elcp setiform, 12 (9–13).

Legs ( Figs. 4 A–K): Leg I 105 (90–110) long; tarsus with 1 apicodorsal and 3 ventral (2 apical and 1 subapical) spine-like setae, 3 solenidia and 4 setiform tactile setae; tibia with 1 solenidion and 2 setiform tactile setae; genu with 2 solenidia and 2 setiform tactile setae; femur with 1 setiform tactile seta; trochanter with 1 setiform tactile seta. Lengths of solenidia: ω1 curved, distally swollen, 12 (10–14), ω2 5 (4–7), ω3 14 (12–18), φ 68 (59–72), σ’ 17 (14–20), σ’’ 12 (9–13). Leg II 96 (87–105) long; tarsus with 1 subapicodorsal and 3 ventral (2 apical and 1 subapical) spine-like setae, 1 solenidion and 4 setiform tactile setae; tibia with 1 solenidion and 2 tactile setae; genu with 1 solenidion and 2 tactile setae; femur with 1 tactile seta; trochanter with 1 setiform tactile seta. Lengths of solenidia: ω curved, distally swollen, 8 (7–10), φ 67 (58–71), σ 3 (2–5). Leg III 66 (58–71) long; tarsus with 1 subapicodorsal and 6 ventral (4 apical, 1 subapical and 1 median) spine-like setae and 3 setiform tactile setae; tibia with 1 solenidion and 1 setiform tactile seta; genu and femur without setae; trochanter with 1 setiform tactile seta. Solenidion φ 60 (58–73) long. Leg IV 69 (60–80) long; tarsus with 1 subapicodorsal and 5 ventral (4 apical and o1 subapical) spine-like seta and 4 tactile setae; tibia with 1 solenidion and 1 setiform tactile seta; genu without setae; femur with 1 setiform tactile seta; trochanter without setae; solenidion φ setiform, 14 (10–19) long.

HOMEOMORPHIC MALE ( Figs. 5–7 ; n= 6; unless otherwise noted, shape of structures similar to females). Dorsum ( Figs 5 A, 6A): Idiosoma nearly ellipsoidal, slightly flattened dorso-ventrally, 270 (265–290 long and 150 (145–165) wide at coxa III level. Prodorsal sclerite 50 (42–60) long and 41 (36–43) wide at anterior margins, with lateral incisions; pattern of punctation and striation similar to female, except that sections of striae longer; supracoxal seta (elc I) 11 (10–15) long. Posterior dorsum without flattened terminal extension, commonly found in males of this genus (e. g. T. entomophagus ). Dorsal idiosomal setae lengths: ro 22 (21–26), ex 32 (27–33), cp 22 (18–24), d2 14 (12–19), e2 20 (16–23), h1 14 (10–16) and h2 28 (22–32). Venter ( Figs. 5 B, 6B): Aedeagus slightly curved, 8 (6–12) long, between coxae IV; h3 44 (38–49) long. Para-anal suckers 10 (9–10) in diameter surrounded by 3 pairs of paraproctal setae: p1, posteriad of each sucker, 5 (4–5) long; p2 laterad of suckers and 5 (4–5) long; and p3, anteriad of suckers and vestigial. Gnathosoma: Chelicera 45 (56–64) long; fixed digit 12 (19–27), with 3 teeth; movable digit 14 (20–23) long, with 2 teeth; cheliceral seta (cha) 3 (2–3) long. Subcapitular seta (subc), 17 (16–29) long; supracoxal seta elcp 7 (6–8) long. Legs ( Figs. 7 A–L): Leg I 71 (67–82) long; tarsus with 1 apicodorsal and 3 ventral (2 apical and 1 subapical) spine-like setae, 3 solenidia and 4 setiform tactile setae; tibia with 1 solenidion and 2 setiform tactile setae; genu with 2 solenidia and 2 setiform tactile setae; femur with 1 setiform tactile seta; trochanter with 1 setiform tactile seta. Lengths of solenidia: ω1 6 (5–9), ω2 4 (4–5), ω3 4 (2– 6), φ 44 (34–47), σ’ 11 (10–16), σ’’ 6 (5–7). Leg II 60 (53–76) long; tarsus with 1 subapicodorsal and 3 ventral (2 apical and 1 subapical) spine-like setae, 1 solenidion and 4 setiform tactile setae; tibia with 1 solenidion and 2 setiform tactile setae; genu with 1 solenidion and 2 setiform tactile setae; femur with 1 setiform tactile seta; trochanter with 1 setiform tactile seta. Lengths of solenidia: ω1 7 (6–7), φ 42 (33–52), σ 3 (3–4). Leg III 51 (42–57) long; tarsus with 1 subapicodorsal and 6 ventral (4 apical, 1 subapical and 1 median) spine-like setae; tibia with 1 solenidion and 1 setiform tactile seta; genu and femur without setae; trochanter with one setiform tactile seta; solenidion φ 43 (40–47) long. Leg IV 57 (53–64); tarsus with 5 ventral (4 apical and 1 subapical) spines, 3 setiform tactile setae and 2 suck-like setae; solenidion φ 5 (4–5) long.

HETEROMORPHIC MALE ( Figs. 7 M–O; n= 20, unless otherwise noted, shape of structures similar to homeomorphic male). Similar to homeomorphic males, except by having tarsus leg III strongly modified, with 2 thick apical and 2 ventral spines, and without pretarsus. In addition, with coxisternal region more sclerotized and with most dorsal and leg setae longer. Idiosoma ellipsoidal, slightly flattened dorso-ventrally, 335 (325–345) long and 180 (165–195) wide at coxa III level. Chelicera 60 (56–64); fixed digit 19 (19–27); movable digit 21 (20–23); cheliceral seta (cha) 3 (2–3). Subcapitular seta (subc) 19 (16–20) long; supracoxal seta elcp 9 (8–9) long. Dorsum: Prodorsal sclerite 66 (62–68) and 49 (44–53) wide at anterior margins; supracoxal seta (elc I) 14 (12–16). Dorsal idiosomal setae lengths: ro 26 (22–29), ex 47 (41–53), cp 37 (29–38), d2 24 (19–26), e2 30 (24–33), h1 22 (18–24) and h2 36 (32–42). Venter: Aedeagus 8 (6–12). Para-anal suckers 11 in diameter, h3 44 (38–49) long, p1 and p2 3 (3–4) long and 5 (4–6) long, respectively, p3 vestigial. Legs ( Figs. 7 M–O): Legs I–II and IV similar to homeomorphic male. Leg I 105 (87–110) long; lengths of solenidia: ω1 10 (9–10), ω2 5 (4–7), ω3 4 (2–6), ε 3 (2– 3), φ 60 (54–67), σ’ 18 (16–20), σ’’ 10 (8–12). Leg II 96 (83– 105) long; lengths of solenidia: ω 8 (6–9); φ 61 (59– 62); σ 3 (2–3). Leg III 71 (63–78) long, with 2 thick apicodorsal spines and 3 ventral (2 apical and 1 subapical) spine-like setae; φ 55 (51–59) long. Pretarsus III absent. Leg IV 67 (61–72) long, φ 4 (3–5).

HETEROMORPHIC DEUTONYMPH. Unknown.

Type material. Holotype female, 15 female, 16 heteromorphic male and 3 homeomorphic male paratypes from chicken feed, BRAZIL: São Paulo state, Piracicaba, 6 April 2012, coll. M. F. C. Barbosa.

Type deposition. Holotype and most paratypes are deposited at the Departamento de Entomologia e Acarologia, Escola Superior de Agricultura “Luiz de Queiroz” (ESALQ), Universidade de São Paulo (USP), Piracicaba. Four females, 4 heteromorphic male and one homeomorphic male are deposited at the University of Michigan Museum of Zoology (UMMZ), Ann Arbor, Michigan, USA.

Etymology. The name cracentiseta is a compound of cracentis (Latin for slender) and seta (Latin for hair), referring to the very thin form of most dorsal setae. The name is a noun in apposition.

Remarks. The genus Thyreophagus is known from adults and heteromorphic deutonymphs. Thyreophagus cracentiseta n. sp. is the second species of this genus reported from Brazil and the first described as new from this country. This new species strongly resembles T. tridens (Fain & Lukoschus 1986) by having similar body length, prodorsal sclerite and having most dorsal setae similar in length. In addition, T. tridens has the spermathecal sclerite arched and the same number of spines on tarsi of legs I–IV as T. cracentiseta . However, T. tridens differs from T. cracentiseta by having a different pattern of punctation on the prodorsal sclerite (punctulate on its anterior two thirds or three quarters and fine striations on the rest of the sclerite) and smaller φ III and φ IV (1.7 and 3.5 times smaller, respectively).

This new species resembles Thyreophagus spinitarsis (Fain, 1982) by having similar patterns on the prodorsal sclerite. The latter differs from T. cracentiseta n. sp. by having the idiosoma about 1.9 times as long, most of the dorsal idiosomal setae about 1.5 times as long and by having the sclerotized base of the spermatheca approximately bell-shaped.

Thyreophagus australis Clark, 2009 is similar to this new species by having Grandjean´s organ anteriorly expanded in membranous finger-like extensions and the male without any projection or sclerite on the posterior opisthosomal region. However, T. australis differs by having females with the idiosoma globose instead of elongate, setae ro and ex more than four times longer and the sclerotized base of the spermatheca as a transverse band.

Thyreophagus gallegoi gallegoi Fain, 1982 resembles this new species by having the idiosoma and dorsal setae of about the same lengths, similar shape of sclerotized base of spermatheca and by producing heteromorphic males. This subspecies differs by having ω1 strongly curved and thin apically and the prodorsal sclerite mostly covered by uniformly fine striae.

Figures

FIGURE 1. Thyreophagus cracentiseta n. sp. (female). (A) Dorsal view. (B). Ventral view.

FIGURE 2. Thyreophagus cracentiseta n. sp. (female). (A) Prodorsal sclerite. (B) Reproductive apparatus (I—Spermatheca; II—Duct of spermatheca; III—Copulatory opening; IV—Sclerite of spermatheca; V—Ovarium; VI—Funnel-shaped structure; VII—Oviduct (C) Genital region. (D) Gnathosoma. (E) Chelicera. (F) Grandjean´s organ.

FIGURE 3. Thyreophagus cracentiseta n. sp. (female). Photomicrography of the reproductive apparatus.

FIGURE 4. Thyreophagus cracentiseta n. sp. (female). (A) Leg I. (B) Tarsus I—dorsal view. (C) Tarsus I—ventral view. (D) Leg II. (E) Tarsus II—dorsal view. (F) Tarsus II—ventral view. (G) Leg III. (H) Tarsus III—dorsal view. (I) Tarsus III—ventral view. (J) Leg IV. (K) Tarsus IV—dorsal view. (L) Tarsus IV—ventral view.

FIGURE 5. Thyreophagus cracentiseta n. sp. (homeomorphic male). (A) Dorsal view. (B). Ventral view.

FIGURE 6. Thyreophagus cracentiseta n. sp. (homeomorphic male) (A) Prodorsal sclerite. (B) Genital region.

FIGURE 7. Thyreophagus cracentiseta n. sp. (A – L homeomorphic male; M – O heteromorphic male). (A) Leg I. (B) Tarsus Idorsal view. (C) Tarsus I—ventral view. (D) Leg II. (E) Tarsus II—dorsal view. (F) Tarsus II—ventral view. (G) Leg III. (H) Tarsus III—dorsal view. (I) Tarsus III—ventral view. (J) Leg IV. (K) Tarsus IV—dorsal view. (L) Tarsus IV—ventral view. (M) Leg III. (N) Tarsus III—dorsal view. (O) Tarsus III—ventral view.