Alloscopus sago Jantarit & Manee, 2025

Jantarit, Sopark, Manee, Nongnapat, Nilsai, Areeruk, Mitpuangchon, Natrada & Pimsai, Awatsaya, 2025, Two new species of the genus Alloscopus Börner, 1906 (Collembola, Orchesellidae, Heteromurinae) from southern Thailand, ZooKeys 1245, pp. 357-381 : 357-381

Alloscopus sago Jantarit & Manee sp. nov.

Figs 1 , 2 , 3 , 4 , 5 , 6 , 7 , Table 1

Material examined.

Holotype: • female on slides: sample # THA_SJ_PLG 08 ; Thailand: Phatthalung: Khuankhanun district , 7°44'02.7"N, 99°59'46.2"E, 25 m asl, sago palm forest, by aspirator, coll. S. Jantarit, 25 viii 2020 . Paratypes: • collection data same as holotype; on slides: • four samples, • one female and • three subadults, by aspirator (2 specimens) and funnel Berlese extraction (2 specimens) .

Description.

Habitus (Fig. 2 A, B ). Medium sized Orchesellidae . Body length (head + trunk) up to 1.5 mm. Scales present on both sides of Ant. I and II, head, body, legs (coxa to femur), ventral tube and furca. Color whitish on all parts of the body without dotted pigments (Fig. 2 A ). Ocular patch present with small red dark spot (Fig. 2 A ). Antennal length shorter than the body. Eyes absent. PAO shape irregular (three overlapping ovals) located just below antennal mac (Figs 4 E , 5 A ). Body slender, not bent nor humped at Th. II level.

Pseudopores (Figs 5 A , 6 C ). Present as round flat disks, as large as mac sockets, on various parts of body. Antennae, with psp on tip of Ant. II and III (2 on each segment). Head with 1 + 1 psp laterally, anterior to PAO; tergites, 1 + 1 psp near axis, from Th. II to Abd. IV; sternite of Abd. IV with one psp near tenaculum (Figs 5 A , 6 C ). Coxae of legs I and II with 1 + 1 psp near longitudinal rows of chaetae. Manubrium with 2 + 2 dorso-apical psp.

Antennae (Fig. 2 ). Elongated, ~ 1.8–2.5 × cephalic diagonal, 0.35–0.41 × body length (head + trunk) (n = 4). Ant. I subdivided, Ant. III and IV annulated, except proximal and distal part (Fig. 3 A – D ). When Ant. II and III fused, segments not annulated. Antennal segment ratio as I (a + b): II: III: IV = 1: 1.13: 1.60: 1.81. Antennal chaetae diverse: ordinary chaetae, S-chaetae (as described in Jantarit and Sangsiri 2020) and scales. Scales oval to rounded, of medium size (7–13 × 14–28 μm), with dense cover of short spicules arranged in more or less regular longitudinal lines; numerous dorsally on Ant. Ib and Ant. II, few on Ant. Ia dorsally; absent on Ant. III and IV (Fig. 3 A, B ). Sens and sens - like chaetae present on all antennal segments, of 13 morphological types similar to that described by Jantarit and Sangsiri (2020), not re-described in detail here.

Ant. I subdivided into Ia and Ib (Fig. 3 A ). Ant. Ia shorter than Ib. Ant. Ia dorsally with 2–4 basal mic (type g) and a row of three or four of thick ciliated chaetae (type b); ventrally with four or five pointed smooth mes (type e), a few thick ciliated chaetae (type b) and one hyaline, smooth mic (type m) (Fig. 3 A ). Ant. Ib dorsally densely covered with scales and ciliated chaetae (types a and b), with a smooth basal mic (type g); apical row with one hyaline, smooth mic (type m), three or four pointed smooth mes (type e) and two or three thin, long, hyaline S-chaetae (type l). Ventrally with a dense cover of ciliated chaetae (type a and b); apical row with three pointed smooth mac (type d) and 8–10 pointed smooth mes (type e or f); lateral side with three or four large swollen, blunt S-chaetae (type h), four or five thin, long hyaline mes (type l) mixed with another three types of S-chaetae (types e, i, k) variously interspersed (Fig. 3 A ).

Ant. II dorsally with scales mixed with many thick ciliated chaetae (types a and b), distally with 5–7 pointed smooth mes (types e or f); one or two swollen S-chaetae (type h); three thin, long hyaline mes (type l); and six thin hyaline rather short chaetae (type k); basally with three pointed smooth mic (type g). Ventrally with a dense cover of thick ciliated mes (type b) with two pointed smooth mic (type g) basally, mixed with three pointed smooth mac (type d), two large swollen S-chaetae (type h), 10–12 thin, long, hyaline S-chaetae (type l), and 12–15 pointed smooth mes (type e or f) (Fig. 3 B ).

Ant. III without scale, chaetotaxy with tendency to form whorls of chaetae. Dorsally dense cover with many thick ciliated mes (types b and c) with two pointed smooth mic (type g) basally, mixed with six types of S-chaetae (types e, f, h, i, k, l) variously interspersed. Ventrally with a dense cover of many thick ciliated mes (type b) with two pointed smooth mic (type g) basally, mixed with four types of S-chaetae (types e, f, h, l) variously interspersed (Fig. 3 C ). Ant. III organ with five sens; sens 1 (type m) longest, hyaline, and acuminate; sens 4 (type i) hyaline, rather long, blunt apically; sens 5 (type j) dark, shortest; sens 2 and 3 (type h) swollen curving rods (Figs 3 C , 4 A ). Antennae sometimes asymmetrical due to the fusion of Ant. III and IV, Ant. III distal chaetae strongly modified when Ant. III and IV fused.

Ant. IV annulated except at tip, without apical bulb, chaetotaxy with tendency to form whorls of chaetae. Dorsally dense cover of many thick ciliated mes (types b and c) mixed with four types of S-chaetae (types e, f, k, l) variously interspersed. Ventrally same as dorsal: dense cover of many thick ciliated mes (types b and c) mixed with four types of S-chaetae (types e, f, k, l) variously interspersed (Fig. 3 D ). Pin projection on apex absent (Figs 3 D , 4 B ). Subapical organite not distinctly knobbed, apical not enlarged, inserted dorsally near tip of Ant. IV with apical guard chaetae (Figs 3 D , 4 B ).

Mouthparts (Fig. 4 C, D ). Prelabral and labral chaetae 4 / 5, 5, 4, all smooth, acuminate, subequal; except chaetae of proximal row slightly longer than others. Four labral papillae, conical, minute (Fig. 4 D ). Ventral complex of labrum with two slightly asymmetrical multi-toothed combs and a pair of thin, sinuous, unequal tubules below. Maxillary outer lobe with one basal chaeta, simple maxillary palp, four sublobal appendages, all smooth (Fig. 4 C ). Labial palp with five smooth, acuminate proximal chaetae, five papillae (A = 0, B = 5, C = 0, D = 4, E = 5) and hypostomal chaeta (H) with two accessory appendages (h 1 and h 2) (Fig. 4 C, D ). Labial papilla E with lateral process subcylindrical apically, not reaching papilla apex (Fig. 4 C ). Mandible asymmetrical (right with 4 and left with 5 teeth) on all examined specimens. Molar plate with three or four strong pointed basal teeth. Maxilla with strong tridentate claw, four or five stout ciliated lamellae with two or three well-developed sharp beaks each side opposite to maxilla capitulum, and thin rod, long, bent inwards towards capitulum.

Ventral head chaetotaxy (Fig. 4 C ). Labial basis as M 1 m 2 rel 1 l 2: chaetae M 1 ciliated, m 2, e and l 2 subequal and longest, r and l 1 subequal and shortest (Fig. 4 C ). Postlabial quadrangle (PLQ) with 2 + 2 weakly serrated chaetae (Fig. 4 C ). Ventral head densely covered with scales and weakly serrated chaetae.

Dorsal head chaetotaxy (Figs 4 E , 5 A ). Dorsal cephalic chaetotaxy with stable chaetae arrangement (Figs 4 E , 5 A ). ‘ An’ series with 8 + 8 chaetae, all mac; ‘ A’ series with 5 + 5 mac (A 0, A 2 – A 5), A 1 as mic; ‘ M’ series with 3 + 3 mac (M 1 – M 3), sutural mac with 7 + 7 mac (S 0, S 1, S 3–6, S 6 i), and three unnamed mic between series ‘ M’ and ‘ S’; interocular series with 3 + 3 chaetae (p as mac, t as mes, r as mic); postsutural area with 3 + 3 mic (Ps 2, 3, 5); postoccipital anterior area with 1 + 1 mac (Pa 5), 1 + 1 short cephalic tric (Pa 6) and 1 + 1 unnamed mic laterally; postoccipital posterior area with 3 + 3 mic (Pp 3, 5, 6); head laterally with several unnamed mac.

Tergites (Fig. 5 A ). Dorsal chaetotaxy in Fig. 5 A . Formulas for Th. II – Abd. V: psp formula as 1, 1 / 1, 1, 1, 1, 0; tric formula as 0, 0 / 0, 2, 3, 2, 0; ms formula as 1, 0 / 1, 0, 1, 0, 0; sens formula as 2, 2 / 1, 3, 3, 3, 3; mac formula as 9, 7 / 3, 1, 3, 6, 4. Mac arrangement stable; multiplets sensu Szeptycki (1979) present only anterior on Th. II.

Th. II with 4 + 4 anterior central mac (a 5, m 2, m 4, m 4 p) and 5 + 5 posterior mac (p 1–3, p 5, p 2 e); with 6 + 6 mic (m 1, m 5, 6 pi, 1 p 2, p 4, acc. p 6), 2 + 2 mes (p 64, p 6) and two unnamed mes laterally.

Th. III with 6 + 6 central mac (p 1–3, p 1 a, a 4–5) and 1 + 1 lateral mac (a 6); 6 + 6 mic (a 2, m 4, p 4–6, m 6 p) and 4 + 4 mes (a 7, m 7, m 6 and unnamed mes).

Abd. I with 3 + 3 central mac (m 2–4) and 7 + 7 mic (a 1–3, a 5–6, m 5, p 6) and a row of 2–3 + 2 – 3 unnamed mes laterally (only one chaeta shown in Fig. 5 A ).

Abd. II with 1 + 1 central mac (m 3); 13 + 13 chaetae (a 1–3, a 6–7, m 3 e, m 5–6, p 4, p 6–7 as mic; a 5 and m 2 as tric) and two unnamed mic laterally, not shown in Fig. 5 A .

Abd. III with 1 + 1 central mac (m 3) and 2 + 2 lateral mac (p 6, pm 6); 14 + 14 chaetae (a 1–3, a 6–8, m 3 e, m 4, p 4–6 as mic; a 5, m 2, m 5 as tric); with one unnamed mic and three unnamed mes laterally not shown in Fig. 5 A .

Abd. IV with 2 + 2 central mac (A 6, B 5); 4 + 4 lateral mac (E 3, E 4, Ee, F 1); with at least 16 + 16 chaetae (A 2–3, A 5, C 1, F 2, T 1, T 3 as mic; A 6, C 4, D 3, D 4 p, T 6–7, F 3 a as mes; T 2 and T 4 as tric); and at least 12 + 12 S-like chaetae.

Abd. V with 3 + 3 central mac (m 2–3, p 1) and 1 + 1 lateral mac (m 5); with 12 + 12 chaetae (a 1, a 3, a 5, p 1 p, p 3 pi, 3 pe, 5 pi as mic, a 6, ap 6, m 4–5, m 5 a as mes); with at least three unnamed mes laterally, not shown in Fig. 5 A .

Abd. VI with at least 24 + 24 ciliated mac mixed with mes, all chaetae not shown in the illustration (Fig. 5 A ). Dorsal anal valve with two strong and long smooth chaetae, at least 17 chaetae (serrated mes mixed with mac), mic not seen.

Legs (Fig. 6 A – D ). Covered with ordinary ciliated chaetae (mes – mac), smooth chaetae, and scales; mic not observed.

Subcoxa of leg I with 3 + 3 mac, subcoxa of leg II with 4–5 + 4 – 5 mac and 4 + 4 mes, subcoxa of leg III with 3–4 + 3 – 4 mes anteriorly and 3–4 + 3 – 4 mac posteriorly.

Coxa of leg I with two proximal psp, four or five anterior mes and four posterior mac; coxa of leg II with six mac in anterior row, four or five mac in posterior row and one proximal psp in between, at least row of two or three mes posteriorly; coxa of leg III with at least seven chaetae (3 mes anteriorly, 3 mac posteriorly, 8–10 mes in between, psp not seen. Trochanteral organ with 18–21 smooth, straight, unequal spine-like chaetae (Fig. 6 D ).

Tita of leg III slightly longer than tita of legs I and II. Distal whorl of tita with ten subequal ciliated chaetae, irregularly arranged, and a thin, acuminate, smooth tenent hair. Tita with rows of nine or ten long smooth chaetae internally, two smooth chaetae latero-distally (Fig. 6 A, B ). Ventro-distal smooth chaeta of tita III thin, erected, pointed, longer than tenent hair or unguiculus. Pretarsal mic minute on anterior and posterior sides.

Ungues outer teeth present; inner edge with paired basal teeth, unpaired teeth absent. Unguiculus ~ 1 / 2 as long as inner edge of ungues, slightly swollen baso-internally, pointed apically, with large outer tooth (under light microscope), devoid of inner teeth (Fig. 6 A, B ).

Ventral tube (Fig. 7 A, B ). Ventral tube ~ 1.5 × longer than wide; with scales on posterior side (Fig. 7 A ). Anteriorly with 7 + 7 subequal ciliated chaetae and one weakly serrated chaeta, (Fig. 7 B ). Posteriorly with 2 + 2 smooth chaetae, and 3 + 3 row of ciliated chaetae mixed with two or three weakly serrated chaetae proximally (Fig. 7 A ). Lateral flaps with 11 + 11 smooth chaetae (Fig. 7 A, B ).

Furcal complex (Figs 6 C , 7 C – E ). Tenaculum with one smooth chaeta and four large teeth of decreasing size from the basal to distal one on each ramus (Fig. 6 C ).

Ratio of manubrium: dens: mucro = 4.2: 6.44: 1 (n = 6).

Mucrodens 1.5–2.0 × longer than manubrium (n = 6). Manubrium dorsally densely covered with ciliated mes, row of 5 + 5 smooth chaetae on each side (Fig. 7 C ). Manubrial plate with 2 + 2 psp and four ciliated chaetae. Manubrium ventrally densely covered with medium size scales, one short smooth chaeta basally. Dens curved, tapering, constituted of a rather short basal part hardly crenulated, long medial part with well-defined dorsal crenulations and short, thinner, smooth distal part, ~ 4 × mucro length. Dens basally with 1 + 1 row of four or five finely ciliated spines on inner side (normally with 4 + 4), sometimes asymmetrical and 1 + 1 long smooth chaetae latero-externally (Fig. 7 C ). Laterally dens covered with ciliated mes (Fig. 7 C ), ventrally with medium-sized elongated scales mixed with ciliated mes; scales absent on distal non-crenulated part (Fig. 7 C, E ). Mucro bidentate, without basal spine (Fig. 7 E ).

Genital plate as in A. whitteni Jantarit & Sangsiri, 2020 . Female with 2 + 2 smooth mic, one pair on anterior and posterior lobes. Type series without adult males.

Remarks.

Alloscopus sago sp. nov. shows morphological similarity to A. whitteni that is found in a cave environment in Phang Nga Province, southern Thailand. Both species share several morphological traits, including the presence of a red dark red eye patch; the absence of an apical pin chaeta on Ant. IV; number of “ An ” (= 8), “ A ” (= 5), “ M ” (= 3) and “ S ” (= 7) series on dorsal head; labial basis formula (M 1 m 2 rel 1 l 2); number of processes of papilla E (5); number of spiniform labral papillae (4); number of mac on Th. III (7 + 7); number of lateral mac on Abd. III (2 + 2); ungual inner side without unpaired teeth; and presence of smooth chaetae on tibiotarsi. However, A. sago sp. nov. differs from the all other blind Alloscopus species, including A. whitteni , by number of mac on Th. II with only nine mac (vs 10–13 mac) and the presence of 5 + 5 smooth chaetae on manubrium (vs 3–4 + 3 – 4). This new species can also be distinguished from A. whitteni by a combination of the following characters: longer antennae (1.8–2.1 vs 1.5); body without pigment (vs orange pigment); 9 + 9 mac on Th. II (vs 10 + 10); small number of chaetae on posterior face (7–8 vs 12); and smooth chaetae on manubrium (5 + 5 vs 4 + 4). The habitat of the new species is distinctly different, as it is found exclusively within the bark of the sago palm tree, whereas the latter species is confined to cave environments. Diagnostic characters of this new species and all seven closely related blind species are provided in Table 1 .

Etymology.

The species name is derived from the habitat in which this new species was found, the sago palm ( Metroxylon sagu Rottb. ), a true sago palm typically found in lowland freshwater swamps. The name emphasizes the presence of springtails in the sago palm forests, which are native to southern Thailand, and underscores the ecological significance of the sago palm that serves not only as a major source of starch for commercial purposes but also as a habitat for numerous species, including the newly described Collembola species.

Ecology.

The new species is exclusively found on the old bark of the sago palm ( Metroxylon sagu Rottb ) at the lower trunk level (Figs 1 B , 2 F ). The sago palm population in this area is dense and is located within a protected zone managed by the local community at Ban Huay Pru, Khaun Khanun Subdistrict, Khaun Khanun District, Phatthalung Province, designated for the cultivation and harvesting of sago palm. The sago palm patch spans approximately 4.75 hectares (47,500 square meters) and is surrounded by agricultural areas, including rice fields, orchard plantations, and residential communities.

Figures

Figure 1. The map of Thailand (top right) shows a rectangle outlining the southern region, with the arrow indicating an enlarged view of this area, illustrating the distribution of the new species of Alloscopus described in this study: Alloscopus jantapasoae sp. nov. (1); A. sago sp. nov. (2); A. Photograph of the cave habitat where A. jantapasoae sp. nov. was collected, showing a human figure for scale, and B. Photograph of the bark of sago palm tree, the habitat where A. sago sp. nov. was discovered.

Figure 2. Habitus of Alloscopus in this study: A, B. A. sago sp. nov. photographs from the stereomicroscope and SEM and C, D. A. jantapasoae sp. nov. photographs from stereomicroscope and SEM; E. The patch of sago palm trees (Metroxylon sagu Rottb); F. Enlarged detail of sago palm barks. Scale bars: 500 μm (B, D).

Figure 3. Alloscopus sago sp. nov. A. Dorso-lateral side of Ant. Ia + Ib; B. Dorso-lateral side of Ant. II; C. Dorso-lateral side of Ant. III; D. Dorso-lateral side of Ant. IV; E. Antennal chaetae type as per Jantarit and Sangsiri (2020). Scale bars: 40 µm (A – C); 50 µm (D); 10–20 µm (E).

Figure 4. Alloscopus sago sp. nov. continued, A. Antennal Organ III (AOIII) (right side) with its typical 5 chaetae; B. Tip of Ant. IV with subapical organite (green arrow) and guard chaeta (red arrow); C. Head ventral chaetotaxy anteriorly, focusing on labial basis and PLQ chaetae; D. Labial palp of left side, marked with red labels, displays five papillae (A – E), while yellow arrows highlight four labral papillae. Scale bars: 40 µm (A); 20 µm (B, D); 100 µm (C).

Figure 5. Head and body chaetotaxy of A. Alloscopus sago sp. nov. and B. A. jantapasoae sp. nov. Scale bars: 200 µm.

Figure 6. Alloscopus sago sp. nov. continued, A. Claw complex, with red arrow indicates smooth chaetae distally; B. Tibiotarsi, showing rows of smooth chaetae and claw morphology; C. The tenaculum and psp in close proximity to each other.; D. Trochanteral organ. Scale bars: 20 µm (A, D); 50 µm (B); 10 µm (C).

Figure 7. Alloscopus sago sp. nov. continued, A. Ventral tube, posterior view and lateral flap; B. Ventral tube, anterior view, and lateral flap; C. Dorso-lateral manubrium with red arrows indicating rows of smooth chaetae; green arrow shows a smooth chaeta on dens basally; D. Proximal part of dens and spines; E. Mucro and distal part of dens. Scale bars: 40 µm (A, B); 50 µm (C); 10 µm (D); 30 µm (E).