Sphaerobelum nonghinensis Srikampha & Srisonchai, 2025

Sphaerobelum nonghinensis Srikampha & Srisonchai , sp. nov.

Figs 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5 , 14 A, B View Figure 14 , 15 E, F View Figure 15 , 16 View Figure 16

Type material.

Holotype. Thailand • ♂ ( MZKKU -MYR 0001 ), Loei Province, Nong Hin District, Suan Hin Pha Ngam (Hin Pha Ngam Park), 17°03'02"N, 101°44'40"E, ca. 680 m a. s. l., 23 October 2021, K. Srikampha and N. Srimongkol coll. GoogleMaps Paratypes. Thailand • 17 ♂♂, 12 ♀♀ ( MZKKU -MYR 0002 ), 2 ♂♂, ♀ for SEM ( MZKKU -MYR 0002 ), same data as holotype GoogleMaps . • 4 ♂♂, 9 ♀♀ ( MZKKU -MYR 0002 ), same data as holotype, 27 September 2024, K. Srikampha coll. GoogleMaps • ♂, ♀ ( CUMZ - MYR 0031 ), same data as holotype GoogleMaps . • ♂, ♀ ( NHM), same data as holotype GoogleMaps . • ♂, ♀ ( NHMD), same data as holotype GoogleMaps . • ♂, ♀ ( NHMW), same data as holotype GoogleMaps . • ♂, ♀ ( ZFMK), same data as holotype GoogleMaps .

Additional material examined — non-type.

Thailand • ♀ ( MZKKU), Loei Province, Nong Hin District, Wat Tham Pha Fai , 17°02'37"N, 101°44'10"E, ca. 718 m a. s. l., 12 September 2021, K. Srikampha coll. GoogleMaps • ♂ ( MZKKU), Loei Province, Nong Hin District, Wat Tham Sung (Wat Tham Pha Nang Khoi), 17°04'31"N, 101°47'08"E, ca. 344 m a. s. l., 12 September 2021, K. Srikampha coll. GoogleMaps

Diagnosis.

S. nonghinensis sp. nov. differs in the femur of the legs, in which only the apical margin carries a few teeth, a character only shared with S. bicorne Attems, 1938 , S. bolavensis Wesener, 2019 , as well as S. onyx sp. nov. and S. petramurum sp. nov. described below. S. nonghinensis sp. nov. differs from both S. bicorne and S. bolavensis in the presence of a “ hook ” on telopoditomere 4 of the posterior telopods. Differs in the unique colouration pattern, black, with orange markings only on the thoracic shield and anal shield from other known Sphaerobelum species, e. g., from S. petramurum sp. nov., which is greenish-bluish brown, and from S. onyx sp. nov., which is entirely black. S. nonghinensis sp. nov. has a “ hook ” on telopoditomere 4 of the posterior telopods that resembles those of S. clavigerum , S. hirsutum , S. laoticum , S. onyx sp. nov., S. petramurum sp. nov., S. schwendingeri , S. separatum , and S. splendidum . The new species differs from S. clavigerum in the presence of a single short or dot-like locking carina on the anal shield (vs. 3 × long), from S. hirsutum and S. separatum in the presence of glabrous tergites (vs. hairy). It differs from S. laoticum and S. schwendingeri by having <60 apical cones on antenna (vs. 81–86 in S. laoticum , 36–73 in S. schwendingeri ) and by having a greenish-brown antenna (vs. red). It differs from S. splendidum by having an elongated telopoditomere 2 of the anterior telopod (vs. short, as long as telopoditomere 3).

Description.

Measurements: Male holotype; body length 26.1 mm; width (broadest) of thoracic shield 13.0 mm, of tergite 7 = 13.1 mm; height of tergite 7 = 7.7 mm. Males: body length = 24.4–27.9 mm; width (broadest) of thoracic shield = 11.8–12.5 mm, of tergite 7 = 12.2–13.1 mm; height of tergite 7 = 7.9–8.0 mm. Females: body length = 25.7–28.7 mm; width (broadest) of thoracic shield = 13.1–14.6 mm, of tergite 7 = 14.0– 15.7 mm; height of tergite 7 = 8.4–10.1 mm.

Colouration (Fig. 2 A – F View Figure 2 ): Live specimens with dark body colour, shiny. Head, collum, and tergites shiny black. Lateral margins of both thoracic and anal shields contrastingly orangish brown. Antennae brown. Legs and venter greenish brown. Specimens in 70 % alcohol after 4 years changed to brownish black.

Head (Fig. 3 A, E View Figure 3 ): Trapeziform, sparsely setose; setae on anterior part longer than posterior one; each seta located inside small pit. With 75–87 ommatidia (ocelli) in males and 72–78 in females. Aberrant ommatidium present at brim of antennal groove. Organ of Tömösváry situated at brim near ocelli, separated from eye field. No sclerotised crest / ridge between antennal socket and eye field.

Antennae (Figs 2 B, C View Figure 2 , 3 A – D View Figure 3 ): Short and stout, covered by long and dense setae; last antennomere reaching back to leg pair 2 or 3. Lengths of antennomeres 6> 5 = 4> 3> 2 = 1. Antennomere 6 apically rounded, oval; with sensilla basiconica apically. Apical disc flat, with 14–50 apical cones in male or 29–34 in female.

Epipharynx (Fig. 3 F View Figure 3 ): With a regular central tooth (ct); laterally with numerous external teeth (et), short; inner area of each side with a row of crenate spines (rsp).

Gnathochilarium (Fig. 3 G, H View Figure 3 ): With long and dense setae. Lamellae linguales (ll) rectangular, flat apically. Central pads (Cp) modified, with numerous sensory cones. Stipites (st) large; located laterally to lamellae linguales. Mentum (me) large, fused. Lateral palpi inconspicuous. Inner palpi (ip) with sensory cones (sc) arranged in two fields.

Mandibles (gnathal lobe) (Fig. 3 I View Figure 3 ): With undivided external tooth (Et) and with conspicuous 3 - combed inner tooth (3 it). With 4–5 rows of pectinate lamellae (pl). Inner area (Ia) with group of tiny teeth. Molar plate (mp) flat, velvet-like; lacking a membranous fringe. Condylus (co) conspicuous, apically with two distinct ridges.

Tegument (Fig. 2 A – F View Figure 2 ): Shiny; collum, thoracic shield, tergites, and anal shield sparsely microscopic setose; each seta located in an inconspicuous pit. Anterior margins of midbody tergite and anal shield with a few rows of long setae.

Collum (Figs 2 B View Figure 2 , 3 A View Figure 3 ): Subsemicircular; tip of lateral margin obtuse.

Thoracic shield: Anteriorly with shallow and large grooves separated by a long ridge. Groove and ridge smooth, without setae. Sloped towards groove laterally with 4 inconspicuous keels.

Midbody tergite: With a row of oval impressions at anterior margin. Tips of midbody paratergites projecting posteroventrad.

Paratergites: Paratergites 3 and 4 slender, slightly attenuate; tip sharp. Paratergites 5–12 wide; tip obtuse.

Anal shield: Large and well-rounded in female, slenderer in male. Underside with a single, short, black locking carina, as long as those of tergites, sometimes dotlike.

Endotergum of midbody tergite (Fig. 14 A, B View Figure 14 ): Posterior margin (pm) flat, regular. Outer area (oa) wide; without setae. Marginal bristles arranged in 3–4 rows; tips of the longest bristles not protruding above posterior margin. Middle area (ma) with a single row of conspicuous, circular cuticular impressions (cp); distance between impressions twice as long as individual diameter. Inner area (ia) without tubercles or setae.

Pleurites (laterotergites): First pleurite slender, boomeranglike; apical margin attenuated, strongly projecting into a wide tip. Pleurite 2 wider than the first one, projecting into obtuse tip. All remaining pleurites flat and broad, apical margin slightly extended.

Subanal plate (Fig. 4 G View Figure 4 ): Densely setose; large and wide; well-rounded; apical margin slightly concave.

Stigmatic plates (Fig. 4 C View Figure 4 ): First stigmatic plate slender, apex well-rounded. Second stigmatic plate in both sexes not curved.

Legs (Fig. 4 A – F View Figure 4 ): All podomeres sparsely setose. Coxa (cx) large; coxal process absent in first legs; legs 2–21 laterally with conspicuous coxal ridge (legs 2 of female slightly smaller than in male). Prefemur (pre) short; apico-mesally with inconspicuous projection. Femur (fe) 1.5 times longer than wide, with long femoral ridge in all leg pairs; apico-mesally with dentate margin, carrying inconspicuous teeth (Sp). Postfemur (po) and tibia (ti) short. Tarsus (ta) of midbody legs quite long, 3.4 times longer than wide, as long as length of femur + postfemur. First two leg pairs without apical spine; leg-pair 1 with 2 ventral spines; leg-pair 2 with 5 ventral spines; leg-pair 3 with 5 or 6 ventral spines and 1 apical spine; leg pairs 4–21 with 6 or 7 ventral spines and 1 apical spine. Claw normal, with a small notch at base.

Male gonopore (Fig. 4 E View Figure 4 ): Small, triangular; covered by long setae.

Anterior telopods (Fig. 5 A, C, E – G View Figure 5 ): First telopoditomere large, stout, apically widening. Telopoditomere 2 large, with projection as long as telopoditomere 3. Immovable finger (process of telopoditomere 2) short; clearly seen in posterior and ventral views; almost as long as telopoditomere 3; strongly curved; attenuate near tip; tip obtuse. Telopoditomere 3 indistinctly demarcated from telopoditomere 4 (with inconspicuous suture), both of equal length and cylindrical; telopoditomere 3 apically with a single spine and telopoditomere 4 with two spines or five spines on some specimens.

Posterior telopods (Figs 5 A – D View Figure 5 , 15 E, F View Figure 15 ): With 4 telopoditomeres. First telopoditomere rectangular, longer than wide. Telopoditomere 2 large. Immovable finger (process of telopoditomere 2) long, massive, hammerlike, 2 times longer than wide, with a characteristic, apically extremely swollen, round, inner margin. With single spine; with thin dark spot near apex; tip in situ, curving ventrad; antero-apical margin a bit collapsed to accommodate tip of telopoditomere 4. Telopoditomere 3 stout; 2 times longer than wide, with single spine at excavate inner margin. Telopoditomere 4 relatively short, half as long as telopoditomere 3, strongly tapering toward apex; with two spines; immediately curved midway by forming a digitiform tip. Telopoditomeres 1 and 2 in anterior view covered by sparse setae, in posterior view glabrous. Telopoditomeres 3 and 4 glabrous. Inner horns with sharp tips, directed posteriad.

Female sexual characters (Fig. 4 F View Figure 4 ): Vulva slightly short and slender; sparsely setose; covering almost 1 / 3 of coxa; extending mesally near base of prefemur. Operculum (op) round, slender, mesal margin protruding into a short, well-rounded lobe. Bursa (bu) relatively long, demarcated from operculum by a triangular groove.

Etymology.

Named after Nong Hin District, where all specimens were collected. Adjective.

Distribution and habitat

(Fig. 2 G, H View Figure 2 ). Sphaerobelum nonghinensis sp. nov. is currently known only from the type locality in Nong Hin District, Loei Province. This new species was observed during the daytime in an evergreen forest within limestone habitat. Individuals typically conceal themselves beneath thick layers of leaf litter and decayed logs on rocky surfaces or in crevices, highlighting their adaptation to this unique environment.

Remarks.

Females of S. nonghinensis sp. nov. are generally similar in size to males. This new species features a striking black body colour (but with contrasting orange markings on the thoracic shield and anal shield) and a telopod shape comparable to that of S. onyx sp. nov. However, genetic analysis reveals a notable difference, with a COI genetic divergence of 13.24 % to 14.59 %, indicating a significant level of separation between the two species.