Leptus sidorchukae, Costa & Klompen & Bernardi & Gonçalves & Ribeiro & Pepato, 2019

Costa, Samuel Geremias Dos Santos, Klompen, Hans, Bernardi, Leopoldo Ferreira De Olivei- Ra, Gonçalves, Luciana Cardoso, Ribeiro, Dante Batista & Pepato, Almir Rogério, 2019, Multi-instar descriptions of cave dwelling Erythraeidae (Trombidiformes: Parasitengona) employing an integrative approach, Zootaxa 4717 (1), pp. 137-184 : 159-168

Leptus sidorchukae sp. nov.

Diagnosis

Larva: Idiosoma bearing 114–118 (N= 5) dorsal setae, ventral surface with a shorter pair of barbed setae between coxae I, four setae between coxae II and nine setae between coxae II and III. Palp setal formula: 0-2B-2B-3B- 4B1N1ζ1ω. Gnathosoma conical, as barbed, long (40–46) and placed laterally; bs shorter (32–37) than as, thin and barbed; tibia and genu I each bearing one piriform microseta (κ1 and κ2). Deutonymph: center eyes 234–296 (N= 5) apart (O —O), dorsal setae 36–66 long, barbed and evenly distributed. Eyes cornea diameter (O) 17–23 (N= 7), eyes relatively small ( Fig. 10A and B ) when compared with the correlated intersensillar distance ISD/O=10.61–12.76 (N= 7). Crista metopica 293–335 (N= 5) restricted to the anterior half of the idiosoma. Sensillar area with 3–4 short (30–46, N= 5) barbed setae, anterior to sensilla. Tibia and genu I each with one microseta (κ) placed at their distal end, shape similar to that in larva ( Fig. 10C and G ). Female: O=24–28; O—O= 369–535 (N= 5). Eyes relatively small ( Fig. 11A and B ) when compared with the intersensillar distance ISD/O= 14.39–15.2, N= 3. Crista metopica 417–490 (N= 5) restricted to the anterior half of idiosoma. Anterior sensillar area with 7–8 short (40–70, N= 5) barbed setae anterior to sensilla. Genital pore 270–302 (N= 5) with two pairs of oval, small, and overlapping genital acetabula, placed at the posterior half of the genital pore. Tibia and genu I each with one microseta (κ) placed at their distal end, shape similar to that in larva. Male: O—O=370–414 (N= 2), O=26–29 (N= 2); Eyes relatively small ( Fig. 13A, B and 22A ) when compared with the intersensillar distance ISD/O=14.17–14.23 (N= 2). Similar to females in most respects. Genital pore 198, with 25 setae on each genital epivalve (N= 1). Internally, operculum composed of two anteriorly articulated longitudinal sclerites of the ejaculatory complex with 11 eugenital setae on each side over protuberances (N= 1).

Type Material. Holotype: Larva UFMG AC 151093 collected at 19°34’36.0”S, 44°01’13.0”W, in an unnamed limestone cave, Pedro Leopoldo municipality, Minas Gerais State, Brazil, between July 22 th and August 18 th of 2015. Larval paratypes: UFMG AC 150875, 151098, 151100 and 151510. Deutonymphal paratypes: UFMG AC 150321 , 150323, 150326, 151101, 151206, 150710, 150711, 150717, 150729, 151208 and 150730. Female paratypes: UFMG AC 150693, 151245, 151107 and 151108. Male paratypes: UFMG AC 150853, 150725 and 150932. The specimens were collected in the entrance, penumbra and aphotic zone from Gruta do Salitre and other unnamed caves (See Table I for detailed collecting data).

Description

Larvae: Measurements summarized in Table II. Idiosoma oval. Dorsal scutum punctate, wider than long, with two pairs of scutella and two pairs of sensilla; anterior sensilla more barbed in distal half, posterior sensilla homogeneously barbed ( Fig. 8C ). Idiosoma bearing 114–118 (N= 5) dorsal setae, ventral surface with a short pair of barbed setae between coxae I (1a), four setae between coxae II and nine setae between coxae II and III, followed by 31–35 barbed setae ( Fig. 8D, E ).

Gnathosoma conical, as barbed, long (40–46; N= 5) and placed laterally; bs shorter (32–37) than as, thin and barbed. Short (16) and smooth galeala (cs) visible in only a few specimens. Palpal setal formula: 0-2B-2B-3B- 4B1N1ζ1ω. Palp tibial claw entire ( Fig. 8A, B ).

Legs with seven segments each, all normal setae barbed ( Fig. 9 ). All tarsi bearing a pair of claws and a claw-like empodium; anterior claw with onychotrichs (tiny spine-like projections), posterior claw lacking a hook element and bearing ventral setules ( Fig. 9D, E, F ). Tibia and genu I each bearing one distally enlarged, piriform, distal microseta ( Fig. 9A ).

Leg setal formula:

Leg I: Ta—23B,1Cp, 2 ζ, 1 ω; Ti—15B, 1κ, 2 φ; Ge—8B, 1κ, 1σ; TFe—5B; BFe—3B; Tr—1B; Cx—1B.

Leg II: Ta—22B, 1 ω, 2 ζ; Ti—15B, 2 φ; Ge—8B, 1κ, 1σ; TFe—5B; BFe—3B; Tr—1B; Cx—1B.

Leg III: Ta—22B, 1 ζ; Ti—15B,1 φ; Ge—8B; TFe—5B; BFe—2B; Tr—1B; Cx—1B.

Deutonymph: Measurements summarized in Table III. Color in life unknown. Idiosoma oval ( Fig. 10A ). Dorsal setae 36–66 (N= 5) long, barbed and homogeneous in shape, size and color ( Fig. 10B ). Short (293–335) crista metopica restricted to anterior half of idiosoma, positioned between a pair of small eyes (O= 17–23, N= 7), eyes relatively distant from each other (center eyes 234–296 apart; N= 5) and 117–148 (N= 5) distant from the center of the crista metopica. To compare the eye development to other species, we introduce the ratio of intersensilar distance to eye cornea diameter, ISD/O=10.61–12.76 (N= 7). This ratio shows the reduction of the eyes in relation to the ISD. Crista with two pairs of filiform sensillary setae with faint setules and two to four short (30–46) barbed setae in anterior sensillar area, inserted anterior to sensilla ( Fig. 10B ). Anal valves weakly developed, bearing 3–8 (N= 5) setae on each valve, asymmetrically distributed ( Fig. 10H ).

Gnathosoma conical bearing two long and stylet-like chelicera ( Fig. 10A ). Palps long, bearing numerous barbed setae, palp tibial claw entire; length similar to that of cylindrical palp tarsus, which carries numerous distal eupathidia ( Fig. 10D, E ).

Relative legs lengths: IV>I> III>II. Leg scobalae, numerous, pointed and barbed ( Fig. 10C and G ). Tibia and genu I each bearing one piriform microseta (κ1 and κ2); shape and position as in larva ( Fig. 10F, E ).

Female: Measurements summarized in Table IV. Color in life unknown. Idiosoma oval ( Fig. 11A ). Dorsal setae similar to deutonymph ( Fig. 10B , 11 A–B). Short crista metopica (417–490 N= 5) restricted to anterior half of idiosoma; positioned between a pair of small eyes, which are 369–535 (N= 5) apart. Crista carries two pairs of filiform sensillary setae with faint setules and 7–8 short (40–70, N= 5) barbed setae in anterior sensillar area, inserted anterior to sensilla ( Fig. 11B ). Genital pore elongated, bearing two pairs of small genital acetabula (G. ac.), both with the same oval shape and inserted in posterior half of genital pore ( Fig. 12B ).

Gnathosoma conical ( Fig 11A ), bearing two stylet-like cheliceral blades. Palps bearing numerous barbed setae of the same shape; palp tibial claw entire, similar in length to the cylindrical palp tarsus ( Fig. 11C, D ); palp tarsus with numerous distal eupathidia ( Fig. 12C ).

Relative legs lengths: I>IV>III>II. Leg scobalae, numerous, pointed and barbed ( Fig. 12A, D ). Tibia and genu I each bearing one piriform microseta (κ1 and κ2, Fig. 12A, D ).

Male: Measurements are summarized in Table V . Color in life unknown, somatic characters similar to females. Dorsal setae barbed ( Fig. 13A, B ). Short (474–560 N= 3) crista metopica positioned between a pair of small eyes and restricted to anterior half of idiosoma. Crista with two pairs of filiform sensillary setae with faint setules and 6–8 short (40–70 N= 3) and barbed setae in anterior sensillar area, inserted anterior to sensilla ( Fig. 13B ). Anal pore positioned ventrally near genital pore ( Fig. 13C ).

Genital pore elongated, bearing 25 setae on each side of the external border. Internally, the operculum is composed of two, anteriorly articulated, longitudinal sclerites of the ejaculatory complex each of which has 11 eugenital setae over protuberances on each side (black arrow on Fig. 13C ). Tips of proximal arms of ejaculatory complex distinguishable and indicated on Fig. 13C .

Gnathosoma conical ( Fig 13E, F ), bearing two stylet-like cheliceral blades. Palps bearing numerous barbed setae with the same shape, palp tibial claw entire; length similar to that of the cylindrical palp tarsus ( Fig 13E, F ); tarsus with numerous distal eupathidia ( Fig. 13H ).

Relative legs lengths: I>IV>III>II. Leg scobalae, numerous, pointed and barbed. Tibia and genu I each bearing one piriform microseta (κ1 and κ2, Fig. 13D, G ).

Figures

FIGURE 8. Leptus sidorchukae sp. nov. larva. A: Gnathosoma ventral view; B: Palp-tarsus; C: Dorsal scutum; D: Idiosoma dorsal view; E: Idiosoma ventral view. Scale: A= 100 µm, B= 20 µm, C= 50 µm; D and E= 200 µm.

FIGURE 9. Leptus sidorchukae sp. nov. larva. A: Leg I; B: Leg II; C: Leg III; D: Distal portion of tarsus I; E: Distal portion of tarsus II; F: Distal portion of tarsus III. Scale: A, B, C= 100 µm; D, E and F= 20 µm.

FIGURE 10. Leptus sidorchukae sp. nov. deutonymph. A: General view; B: Crista metoptica, eyes and dorsal setae (detail); C: Leg I, tibia and tarsus, relative position of micro setae κ1 and κ2 indicated; D: Palp dorsal view; E: Palp ventral view; F: Palptarsus; G: Piriform microseta κ1; H=Anal pore. Scale: A= 400 µm, B and C= 200 µm; D and E= 100 µm; F, G and H= 50 µm.

FIGURE 11. Leptus sidorchukae sp. nov. female. A: General view; B: Crista metopica, eyes and dorsal setae; C: Palp dorsal view; D: Palp ventral view. Scale: A= 1000 µm, B= 200 µm, C and D= 100 µm.

FIGURE 12. Leptus sidorchukae sp. nov. female. A: Tarsus and tibia I; B: Ventral view showing the anal and genital pore; C: Palp tarsus dorsal view; D: Palp ventral view. Scale: A and B= 200 µm, C= 50 µm and D= 20 µm.

FIGURE 13. Leptus sidorchukae sp. nov. male. A: General view; B: Crista metopica, eyes and dorsal setae; C: Genital and anal pore, black arrow pointing internal setae of the ejaculatory complex; D: Leg I, tibia and tarsus, relative position of microsetae κ1 and κ2 indicated; E: Gnathosoma ventral view; F: Gnathosoma dorsal view; G: Piriform microseta κ2; H=Palp tarsus. Scale: A= 400 µm, B and C= 200 µm; D and E= 100 µm; F, G and H= 50 µm.

FIGURE 22. Leptus eyes comparison.A: Leptus sidorchukae sp. nov. male, arrow heads indicating the eyes. B: Leptus sp. male UFMG-AC 1300406, arrow heads pointing the eyes. Scale: 200 µm.

Tables

TABLE V. Metric data for the males of Leptus sidorchukae sp. nov. and Charletonia rocciai Treat & Flechtmann, 1979. Some of the metric characters are not applicable for all species and are marked by (NA).

Character	Mean (n=3)	Le. sidorchukae sp. nov. Range			C. rocciai Value (n=1)
IL	1431.0	1322.0	–	1540.0	1845.0
Overall length	1775.0	1685.0	–	1865.0	2037.0
IW	1020.5	793.0	–	1248.0	1337.0
Sba	20.7	19.0	–	22.0	18.9
Sbp	24.0	22.0	–	25.0	19.1
Asens	110.5	109.0	–	112.0	85.0
Psens	127.0	97.0	–	157.0	117.0
ISD	402.7	370.0	–	427.0	375.6
Crista`s common setae	55.3	47.0	–	74.0	76.7–161.4
pDS I	43.7	34.0	–	54.0	54 –123
pDS II	NA	NA	–	NA	28–46
pVS I	39.0	25.0	–	45.0	89–146
pVS II	NA	NA	–	NA	30–38
ASAW	52.0	49.0	–	58.0	104.3
PSAW	48.0	45.0	–	50.0	61.7
CML	526.0	474.0	–	560.0	581.0
O	27.5	26.0	–	29.0	55.1
OL	38.0	38.0	–	38.0	76.4
O—O	392.0	370.0	–	414.0	489.7
OASns	221.5	212.0	–	231.0	277.0
Cx I	198.3	188.0	–	211.0	403.0
Tr I	128.0	118.0	–	137.0	245.6
BFe I	354.0	305.0	–	411.0	454.0
TFe I	447.0	408.0	–	492.0	655.1
Ge I	484.3	451.0	–	537.0	574.6
Ti I	486.7	449.0	–	536.0	622.1
Ta I (L) (with claw)	383.0	366.0	–	414.0	464.2
Ta I (W)	87.3	82.0	–	95.0	193.1
Leg I (without Cx)	2283.0	2097.0	–	2519.0	3084.8
Cx II	286.3	265.0	–	302.0	407.7
Tr II	121.0	111.0	–	133.0	189.6
Bfe II	159.0	143.0	–	168.0	154.3

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