Dactyloscirus sumatranus Corpuz-Raros and Naredo, 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 : 91-95

Dactyloscirus sumatranus Corpuz-Raros and Naredo , sp. nov.

( Figs. 1 – 3 )

Diagnosis. In both sexes, pedipalps thin, curved and abruptly tapered from near base, 1 spls each on basi- and telofemur, 1 bulbous apophysis on telofemur, and 1 bulbous apophysis on joint of genu and tibiotarsus. Median shield absent in females, but a pair of lateral shields present on hysterosoma; male idiosoma strongly sclerotized, dorsal shield covering up to setae e 1. In both sexes, hysterosomal setae c 1, c 2, d 1 and e 1 minute (7 – 10), f 1 and h 1 2.25 – 2.5 times as long as the aforementioned setae. Genital setae 4 pairs: g 4 longest, 1.5 times longer than g 2, g 3, and 3 times than g 1 in females; all pairs subequally short in males. Chaetotaxy of basal segments of legs I–IV in both sexes: coxae 3-3-3-3, basifemora 5-5-3-2, and telofemora 5-5-4-4 sts.

Description. FEMALE. Relatively large, with light brown idiosoma and slightly darker gnathosoma and legs; total body length 851 [851 – 1051 (945.2, n=15)]; width 399 [339 – 532 (455.0, n=14)];

Gnathosoma ( Fig. 1a ): Relatively long and slender, 279 [266–306 (290.0, n=15)] long, about ½ of total body length, 0.49 [0.36 – 0.55 (0.44, n=15)], surface reticulate; hypostome gradually tapered as a cone; with 4 pairs of hypostomal setae and 2 pairs of adoral setae; hg 1 31, hg 2 31, hg 3 73, hg 4 24. Chelicerae 252 [252 – 265 (260.0, n=15)] long, about ¼ of total body length, basal half inflated to about 4 times its distal width, surface reticulate, and with 1 subapical seta ( Fig. 1b ). Pedipalps thin, curved and abruptly tapered from near base; 372 [372 – 412 (385.7, n=14] long, about ½ of total body length, 0.44 [0.36 – 0.45 (0.41, n=14)], extended beyond hypostome by half its length ( Fig. 1a ); 5-segmented and end in a small claw, surfaces strongly reticulate. Chaetotaxy of pedipalpal segments: trochanter 0; basifemur 1 spls, 27 long, arising dorsosubapically on outer margin; telofemur 1 spls, similar in length (27) to that located on basifemur, and 1 bulbous apophysis on outer margin, 17 long and with hyaline tip; genu 4 sts, 1 apophysis on joint of genu and tibiotarsus, 28 long, distally bulbous and hyaline; tibiotarsus 3 sts, 1 minute rodlike tubercle, and 1 tsl, basal sts on inner margin long (24) and fine, terminal solenidion tsl about as long, remaining setae minute.

Idiosoma: Diamond-shaped, with prominent shoulders and sharply tapered posteriorly; 572 [559 – 771 (657.0, n=15)] long. Dorsum ( Fig. 2a ) with a transversely trapezoidal propodosomal shield and a pair of small lateral hysterosomal shields; median hysterosomal shield absent; surfaces of shields reticulate; lateral shields 54 × 7, more than 5 times as long as seta c 1 and about 2/3 of setal distance c 1 -c 2. Propodosomal shield bearing plumose trichobothria vi and sce, and 2 pairs of sts, ve and sci; vi 258 and sce 330 long and almost reaching anus; ve and sci minute (7 – 10), as long as the anteromedian hysterosomals; setal distances: vi–vi 30, vi–ve 78, vi–sce 97, ve–ve 136, ve–sce 23, sce–sce 140, sci–sci 46, sci–sce 51. Hysterosoma striate, striae densely laden with spine-like papillae, those between median setae coarser than lateral ones; complemented with 7 pairs of setae— c 1, c 2, d 1, e 1 and h 2 which minute (7 – 10), f 1 and h 1 which subequal (20 – 24) and 2.25 to 2.5 times longer than the former setae; setal distances: c 1 –c 1 58, c 1 –c 2 62, c 2 –c 2 168, d 1 –d 1 62, e 1 – e 1 58, f 1 –f 1 53, h 1 –h 1 41, h 2 –h 2 74. Cupule im rounded, mid-lateral to and approximately equidistant from setae e 1 and f 1. Venter ( Fig. 2b ). Coxae I, II and III, IV contiguous, surfaces of coxal plates faintly reticulate; areas in intercoxal and opisthosomal regions that are not covered with ventral plates striate-papillate; with 4 pairs of hysterogastral setae arising between coxal plates III+IV, and 1 pair aggenital (or paragenital) setae lateral to genital shields. Genital plates faintly reticulate, each with 4 setae and 2 oval and unequal papillae; seta g 4 longest (51), 1.5 times longer than g 2 and g 3 (34), and 3 times than g 1 (17). Anal region with 2 pairs of anal setae: ps 1 on striated anal shield, and ps 2 on soft cuticle. Cupule ih conspicuous, slit-like, arising between ps 2 and h 2.

Legs: Long and rather stout, lengths: I 466, II 385, III 492, IV 545; all leg segments strongly reticulate; tarsi ending in a pair of conspicuous lobes, and a pair of smooth claws and 4-rayed empodium between the lobes; tarsal lobes II – IV separated from tarsus, those of leg I continuous with distal margin of tarsus. Chaetotaxy of leg segments ( Fig. 3a – d ): coxae I – IV—3-3-3-3 sts; trochantera I – IV—1-1-2-1 sts; basifemora I – IV—5-5-3-2 sts; telofemora I – IV—5-5-4-4 sts; genu I—4 sts, 4 asl, 1 mst in duplex with one of asl; genu II—5 sts, 2 asl; genu III—5 sts, 1 asl; genu IV—5 sts, 2 asl; tibia I—4 sts, 1 asl, 1 bsl, 1 mst in duplex with the asl; tbia II—5 sts, 1 bsl; tibia III—5 sts,1 bsl; tibia IV—4sts, 1 T; tarsus I—24 sts, 1 fam, 3 bsl, 1 mst in triplex with fam and one of the bsl, 1 dtsl; tarsus II—22 sts, 1 bsl, 1 dtsl; tarsus III—22 sts, 1 dtsl; tarsus IV—20 sts, 1 dtsl. Famulus on tarsus I shorter (44) and about ¾ the length (58) of associated bsl; prongs at tip of famulus not observed. One of dorsal sts on basifemora III, IV and telofemora III, IV, noticeably thicker and longer than all others, spiculiform (macrosetae in: Shiba, 1986).

MALE. Total body length 598 [545 – 598 (571.8, n=2)], about half as long (0.58 – 0.6) as that of female; width 279 [239 – 279 (25.9, n=2)].

Gnathosoma: Length 199–213 (206.2, n=2), about 1/3 (0.36, n=2) the total body length, hypostomal setae as in female. Pedipalps ( Fig. 1c ) as in female, 213 [200 – 213 (206.2, n=2)] long, about as long as gnathosoma and 1/3 of total body length; relatively more sclerotized and with more pronounced reticulations than in female. Chaetotaxy of pedipalpal segments as in female, including shapes, relative lengths and location of apophyses. Chelicera shaped as in female, 160 – 170 (165.5, n=2) long.

Idiosoma: Length 346 – 385 (365.0, n=2) long. Dorsum ( Fig. 1d ) almost entirely sclerotized, covered with a single dorsal shield bearing propodosomal and most of hysterosomal setae except f 1, h 1 and h 2 ( Fig. 1e ); setae f 1 and h 1 about 10 long, only slightly longer than any of c 1 to e 1 and c 2 (7), h 2 minute, relative distances between dorsal setae as in female. Trichobothrium sce 228, slightly longer than vi (204), and not reaching anus. Venter as in female but more sclerotized, coxal plates I+II covering almost entire propodosomal venter and almost contiguous at midline, III+IV more narrowly separated on each side; opisthosoma much shorter, striate-papillate; coxal setae 3-3-3-3, and 3 pairs of hysterograstral setae arising on soft cuticle between coxal plates III+IV. Genital plates ( Fig. 1d ) small, with 4 pairs of subequal short setae, and 2 pairs of unequal, oval papillae. Two pairs of setae in anal region: ps 1 on anal plate, and paranal ps 2 on soft, striated cuticle. Cupule ih conspicuous, slit-like, between ps 2 and h 2.

Legs: Chaetotaxy of leg segments: coxae I – IV—3-3-3-3 sts; trochantera I – IV—1-1-2-1 sts; basifemora I – IV— 5-5-3-2 sts; telofemora I – IV—5-5-4-4 sts; genu I—4 sts, 4 asl, 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—4 sts, 1 asl, 1 bsl; tibia II—5 sts, 1 bsl; tibia III—5 sts, 1 bsl; tibia IV—4sts, 1 T; tarsus I—20 sts, 1 fam, 3 bsl, 1 mst in triplex with fam and one of the bsl, 1 dtsl; tarsus II—19 sts, 1 bsl, 1 dtsl, tarsus III—18 sts, 1 dtsl; tarsus IV—17 sts, 1 dtsl. Length of famulus (44) on tarsus I slightly over ¾ the length of associated asl (51); prongs at tip of famulus not observed. One dorsal sts on basifemora III, IV and telofemora III, IV long, thick and spiculiform as in female.

Type material. Holotype female: unknown village in Langkat Regency (3.86540 o, 98.3088 oE), North Sumatra Province, INDONESIA, 10 Jan. 2014, collected by I.L. Lit, Jr., et al., caught by pitfall trap in corn field (sample LKT2-P4- R1 -PF2) . Paratypes: 1 female, same data as for holotype but from a different sample ; 11 females and 3 males, same data as for holotype but collected on 15 Dec. 2014 from 12 different samples ; 1 male, same locality as for holotype, collected from soil in corn field, date unknown ; 1 male, near Pioneer Learning Center , Tanjung Bintang District (5.3839 oN, 105.3834 oE), South Lampung Regency, Lampung Province, INDONESIA, collected from soil in corn field, date unknown .

Additional material. From unknown village in Langkat Regency (3.86540 o, 98.3088 oE), North Sumatra Province, all collected on 15 Dec. 1963 by I.L.Lit, Jr. et al., by pitfall traps in corn field: 4 females and 1 nymph, from 5 different samples; 1 female, collected 10 Oct. 2014 from a different sample; 1 nymph, same data as preceding but date of collection unknown, from soil in corn field. From near Pioneer Learning Center, Tanjung Bintang District (5.3839 oN, 105.3834 oE), South Lampung Regency , Lampung Province, all collected by I.L. Lit, Jr. : 1 female and 1 male, date unknown, from 2 different soil samples; 1 female, date unknown, caught by pitfall trap; 1 female, date unknown, caught by pitfall trap outside experimental plots.

Etymology. The specific epithet refers to the type locality, Sumatra Island.

Remarks. The new species, Dactyloscirus sumatranus sp. nov. closely resembles D. dolichosetosus Den Heyer, 1979 from South Africa in sharing the following features in females: (1) the median shield is absent and a pair of lateral hysterosomal shields is present and longer than the adjacent setae c 1 and c 2; (2) bulbous apophyses are present on pedipalpal telofemur and on the joint of pedipalpal genu and tibiotarsus; (3) the posterior trichobothria sce on the propodosomal shield are very long and reaching the anus; and (4) the same number of femoral setae are present, namely, 5-5-3-2 on basifemora and 5-5-4-4 on telofemora. It differs from the latter species in the following characterstics: (1) the basal half of chelicera is strongly inflated, about four times wider than the distal part (vs. slender and gradually tapered towards the tip of claw in D. dolichosetosus ); (2) the length of dorsolateral hysterosomal shields is about 2/3 the setal distance c 1 –c 2 (vs. equal); (3) hysterosomal setae f 1 and h 1 are at least twice as long as the anterior pairs c 1 –e 1 (vs. only slightly longer); and (4) the length of famulus on tarsus I is only ¾ the closely associated asl (vs. longer).

Figures

FIGURE 1. Dactyloscirus sumatranus Corpuz-Raros and Naredo sp. nov. a—ventral view of female gnathosoma, b—chelicera of female, c—pedipalp of male, d—genito-anal area of male, e—dorsum of male idiosoma. Scale bar: 100 µm.

FIGURE 2. Dactyloscirus sumatranus Corpuz-Raros and Naredo sp. nov., female idiosoma. a—dorsum, b—venter. Scale bar: 100 µm.

FIGURE 3. Dactyloscirus sumatranus Corpuz-Raros and Naredo sp. nov., legs of female. a—leg I (tarsal lobes enlarged at right side), b—leg II, c—leg III, d—leg IV. Scale bar: 100 µm.