Dactyloscirus ladangjagung Corpuz-Raros and Lit, 2022

Corpuz-Raros, Leonila A., Naredo, Jeremy C. B., Lit, Ireneo L. & Caasi-Lit, Merdelyn T., 2022, Two new species of the genus Dactyloscirus (Acari: Prostigmata: Bdelloidea Cunaxidae) from Sumatra, Indonesia, with a key to known species, Zootaxa 5214 (1), pp. 89-103 : 96-100

Dactyloscirus ladangjagung Corpuz-Raros and Lit sp. nov.

( Figs. 4–7 )

Diagnosis. In both sexes, pedipalps short and thick, about ¼ of body length, 5-segmented, with tibiotarsus almost straight and gradually tapered to the tip of claw; basifemur with 1 thick spls, telofemur with 1 thick spls and bulbous apophysis. Apophysis on joint of pedipalpal genu and tibiotarsus present, short and bulbous in female, not observed in male. Female idiosoma with a large propodosomal shield, without median but with a pair of small lateral shields on hysterosoma, and all dorsal setae arising from soft cuticle of hysterosoma; male idiosoma more extensively sclerotized, and bear setae c 1 –e 1 and c 2 on the dorsal shield. In both sexes, hysterosomal setae c 1, c 2, d 1, e 1 and h 2 minute (7 – 10), f 1 and h 1 2.25 times as long as the aforementioned pairs; g4 longest of genital setae. Chaetotaxy of basal leg segments in both sexes: coxae 3-3-3-3, basifemora 5-5-3-2, telofemora 5-5-4-4.

Description. FEMALE. Moderately large and rather stout, with light brown idiosoma and slightly darker gnathosoma and legs; total body length 738 [738 – 745 (741.5, n=2)]; width 332 [333 – 359 (345.5, n=2)].

Gnathosoma ( Fig. 4a ): Length 232 [226 – 232 (229, n=2)], about 1/3 the total body length; hypostome stoutly conical, with 4 pairs of hypostomal setae of which hg 3 longest, and 2 pairs of adoral setae of which anterior pair slightly longer than posterior one. Chelicerae ( Fig. 4b ) 190 [187 – 190 (188.5, n=2)] long, about ¼ the total body length, basally inflated, basal width six times exceeding distal width, surface reticulate, and with 1 subapical seta. Pedipalps ( Fig. 4a ) rather short, 226 [199 – 226 (212.5, n=2)] long, about ¼ of total body length [0.27–0.31 (0.29)], and with tibiotarsus and distal part of genu extending beyond hypostome tip; 5-segmented and ending in small claw, tibiotarsus thick, almost straight and gradually tapered distally; surfaces of all segments minutely reticulate. Chaetotaxy of pedipalpal segments: trochanter 0; basifemur 1 spls, 17 long, arising dorsosubapically on outer margin; telofemur 1 spls, similar in length and location as the former, and 1 short bulbous apophysis (17) with hyaline tip ventrally near inner margin; genu 4 sts and 1 small ovate apophysis (9) arising distally on inner surface; tibiotarsus 3 sts and 1 rod-like tubercle, basal sts on inner margin long and fine (17), terminal solenidion tsl about as long as wide, remaining setae minute.

Idiosoma: Gradually tapered posteriorly from shoulders, 505 [505–519 (n=2)] long. Dorsum ( Fig. 5a ) with a transversely trapezoidal propodosomal shield and a pair of inconspicuous lateral hysterosomal shields; surfaces of shields reticulate; median hysterosomal shield absent; lateral shields 37 × 3, five times as long as seta c1, and about ½ setal distance c 1 –c 2. Propodosomal shield bearing trichobothria vi and sce and 2 pairs of sts (ve and sci); vi 178, sce 221 long; ve and sci minute like anteromedian hysterosomals, 7 – 10; distances between setae: vi–vi 16, vi–ve 56, vi–sce 72, ve–ve 108, ve–sce 14, sce–sce 114, sci–sci 50, sci–sce 34. Soft cuticle of hysterosoma striate-papillate, striae between median setae coarser than lateral ones which fade out to thickened lateral areas of idiosoma; complemented with 7 pairs of setae— c 1, c 2, d 1, e 1 and h 2 which are minute (7 – 10), and f 1 and h 1 which are about twice longer (20) than the former setae; distances between setae: c 1 –c 1 50, c 1 –c 2 46, c 2 –c 2 140, d 1 –d 1 48, e 1 – e 1 44, f 1 –f 1 40, h 1 –h 1 36, and h 2 –h 2 72. Cupule im oval, mid-lateral to and slightly closer to e 1 than f 1.

Venter ( Fig. 5b ). Coxae I, II and III, IV contiguous, surfaces of coxal plates coarsely papillate to minutely reticulate; intercoxal and opisthosomal cuticle striate-papillate; with 4 pairs hysterogastral and 1 pair of aggenital (or paragenital) setae arising on hysterosomal area between coxal plates III+IV and genital plates. Genital plates minutely reticulate, each plate with 4 setae and two oval, subequal papillae; seta g 4 longest (34), g 2 24, g 3 17 and g 1 shortest (14). Two pairs of setae in anal region, ps 1 on anal plate, and paranal ps 2 on soft cuticle surrounding the plate, the latter 3 times longer than former. Cupule ih conspicuous, rounded, arising close to seta ps 2.

Legs: Rather long and stout, lengths: I 372, II 293, III 359, IV 412, the last about half the length of body; all leg segments strongly reticulate; tarsi ending in a pair of conspicuous lobes, a pair of smooth claws and 4-rayed empodium between lobes; tarsal lobes II – IV separated from tarsus, those of I continue with distal end of tarsus. Chaetotaxy of leg segments ( Fig. 6a–d ): coxae I – IV—3-3-3-3 sts; trochantera I – IV—1-2-1 sts; basifemora I – IV— 5-5-3-2 sts; telofemora I – IV—5-5-4-4 sts; genu I—4 sts, 4 asl, and 1 mst in duplex with one of the asl; genu II—5 sts, 1 asl; genu III—5 sts, 1 asl; genu IV—5 sts, 2 asl; tibia I—5 sts, 1 asl, 1 mst in duplex with the asl; tibia II—5 sts, 1 bsl; tibia III—5 sts, 1 bsl; tibia IV—4 sts, 1 T; tarsus I—23 sts, 1 fam, 2 bsl, 1 asl, 1 mst in triplex with fam and the distal bsl, 1 dtsl; tarsus II—22 sts, 1 bsl, 1 dtsl; tarsus III—21 sts, 1 dtsl; tarsus IV—21 sts, 1 dtsl. Famulus on tarsus I 24 long, almost ¾ the length of associated asl (34), prongs on its tip not observed. One of dorsal sts on basifemora III, IV and telofemora III, IV spiculiform, noticeably thicker and longer than all others.

MALE. Smaller than female, total body length 558 – 567 (562.5, n=2), width 226–253 (239.5, n=2).

Gnathosoma: Hypostome as in female, with 4 pairs of hypostomal and 2 pairs of adoral setae, hg 3 longest ( Fig. 4c ). Chelicerae thin, 150 (n=1), about as long as pedipalp, gradually tapered from distal third, basally reticulate, cheliceral seta present ( Fig. 4d ). Pedipalps short and stout like that of female, 146 (n=1), about ¼ of total body length; 5-segmented, end in a small claw ( Fig. 4c ). Chaetotaxy of palp segments: trochanter 0; basifemur 1 spls, 20; telofemur 1 spls, 20, and 1 short bulbous apophysis, length × width, 7 × 7, arising ventrally on inner margin; genu 4 sts, without apophysis; tibiotarsus 3 short sts, 1 minute tubercle and long tsl.

Idiosoma: Length 359 – 394 (376.5, n=2). Dorsal shield large, covering dorsum up to setae e 1, surface minutely reticulate ( Fig. 6a ). Trichobothria vi and sce 204 and 221 long, respectively, plumose, and not reaching anus; setae ve, sci, c 1, c 2, d 1 and e 1 arising on dorsal shield, all short, 7 – 8 long; f 1 and h 1 arising on soft cuticle of opisthosoma, only slightly longer (10) than anterior pairs of hysteronotal setae situated on shield; relative distances between dorsal setae as in female. Venter ( Fig. 6b ) similar to that of female but opisthosoma much shorter and tapered, genito-anal area more sclerotized, and anal setae ps 1 and ps 2 arising dorsally, along with genital setae g 3 and g 4. Three pairs of hysterogastral setae present on soft intercoxal area between coxal plates III+IV. Genital plates strongly sclerotized and bearing genital setae g 1 and g 2 ventrally, 14 and 17 long, respectively; setae g 3 and g 4 arising dorsally, both 10 long.

Legs ( Fig. 7a–d ): relatively short and stout, lengths: I 282, II 238, III 255, IV 299. Chaetotaxy of I – IV leg segments: basal segments from coxa to telofemur as in female; genu I—4 sts, 3 asl; genu II—6 sts, 1 asl; genu III—5 sts, 1 asl; genu IV—5 sts, 1 asl; tibia I—4 sts, 1 asl and 1 mst in duplex, 1 bsl; tibia II—5 sts, 1 bsl; tibia III—5 sts, 1 bsl; tibia IV—4 sts, 1 T; tarsus I—20 sts,1 fam, 2 bsl, 1 mst in triplex with fam and the distal bsl, 1 dtsl; tarsus II—20 sts, 1 bsl, 1 dtsl; tarsus III—19 sts, 1 dtsl; tarsus IV—17 sts, 1 dtsl. Relative lengths of famulus and associated bsl as in female, prongs at its tip not observed. Long spiculiform setae present on basifemora and telofemora III and IV as in female.

Material. Holotype female: unknown village in Langkat Regency (3.86540 o, 98.3088 oE), North Sumatra Province, INDONESIA, 15 Dec. 2013, collected by I.L. Lit, Jr., et al., caught by pitfall trap in cornfield (sample LKT1-P5- R1 -PF-1) . Paratypes: 1 female, same data as for holotype but from sample taken on 10 Jan. 2014 ; 1 male, same data as for holotype but collected from a different sample; and 1 male, same locality data as for holotype, date unknown .

Etymology. The specific epithet refers to the type habitat, in corn ( Zea mays ) fields, and is a combination of the Indonesian (Bahasa) words “ ladang ” (field) and “ jagung ” (corn); it is treated as a Latinized noun in apposition.

Remarks. The female of Dactyloscirus ladangjagung sp. nov. resembles that of D. hoffmannae Swift, 1996 from Hawaii in having the following characterstics: (1) the pedipalpal tibiotarsus is thick and gradually tapered distally; (2) the apophysis on pedipalpal genu is small and narrowly bulbous; (3) the median dorsal hysterosomal shield is absent; and (4) a pair of lateral hysterosomal shields is present. The females of the two species are separated by the number of setae (sts) on some leg segments, viz., 5-5-3-2 on basifemora in D. ladangjagung (vs. 5-5-3- 1 in D. hoffmannae ), and on tibiae 5-5-5-4 (vs. 4-5-4-2). In addition, seta g 4 is the longest of all genital setae in the female of D. ladangjagung while g 3 is longest in D. hoffmannae .

Figures

FIGURE 4. Dactyloscirus ladangjagung Corpuz-Raros and Lit sp. nov. a—ventral view of female gnathosoma, b—chelicera of female, c—ventral view of male gnathosoma, d—chelicera of male. Scale bar: 100 µm.

FIGURE 5. Dactyloscirus ladangjagung Corpuz-Raros and Lit sp. nov., female idiosoma. a—dorsum, b—venter. Scale bar: 100 µm.

FIGURE 6. Dactyloscirus ladangjagung Corpuz-Raros and Lit sp. nov., legs of female. a—leg I, b—leg II, c—leg III, d—leg IV. Scale bar: 100 µm.

FIGURE 7. Dactyloscirus ladangjagung Corpuz-Raros and Lit sp. nov., male idiosoma. a—dorsum, b—venter. Scale bar: 100 µm.