Sphaerobelum petramurum Srikampha & Srisonchai, 2025

Sphaerobelum petramurum Srikampha & Srisonchai , sp. nov.

Figs 10 View Figure 10 , 11 View Figure 11 , 12 View Figure 12 , 14E, F View Figure 14 , 15 I, J View Figure 15 , 16 View Figure 16

Type material.

Holotype. Thailand • ♂ ( MZKKU -MYR 0005 ) Khon Kaen Province, Phu Pha Man District, Ban Khao Wong , 16°38'30.5"N, 101°46'37"E, ca. 247 m. a. s. l., 23 June 2022, K. Srikampha, R. Srisonchai, and MZKKU students coll GoogleMaps . Paratypes. Thailand • ♂, ♀ for SEM ( MZKKU -MYR 0006 ), same data as holotype GoogleMaps . • ♂, 2 ♀♀ ( MZKKU -MYR 0006 ), same data as holotype, 16 May 2021 GoogleMaps . • 3 ♂♂ ( MZKKU -MYR 0006 ), same data as holotype, 26 September 2021 GoogleMaps . • ♂, 2 ♀♀ ( MZKKU -MYR 0006 ), same data as holotype, 23 September 2023 GoogleMaps . • 3 ♂♂, 8 ♀♀ ( MZKKU -MYR 0006 ), same data as holotype, 8 October 2023 GoogleMaps .

Additional material examined — non-type.

Thailand • 3 ♂♂, 2 ♀♀ ( MZKKU), Khon Kaen Province, Phu Pha Man District, Ban Sam Poep , 16°40'44.2"N, 101°52'10"E, ca. 277 m. a. s. l., 17 May 2021. K. Srikampha coll. GoogleMaps • ♀ ( MZKKU), Khon Kaen Province, Phu Pha Man District, Ban Sam Poep , 16°40'44.2"N, 101°52'10"E, ca. 277 m. a. s. l., 23 June 2022. K. Srikampha coll. GoogleMaps • 2 ♂♂ ( MZKKU), ♂ ( CUMZ - MYR 0033 ), ♂ ( NHM), ♂ ( NHMD), ♂ ( NHMW), ♂ ( ZFMK), Khon Kaen Province, Phu Pha Man District, Wat Si Walee Sattha Tham , 16°39'18.0"N, 101°52'14.5"E, ca. 260 m. a. s. l., 1 June 2024. K. Srikampha coll. GoogleMaps • ♀ ( MZKKU), Khon Kaen Province, Phu Pha Man District, Wat Si Walee Sattha Tham , 16°39'18.0"N, 101°52'14.5"E, ca. 260 m. a. s. l., 14 September 2024. K. Srikampha coll. GoogleMaps • 3 ♂♂, ♀ ( MZKKU), Khon Kaen Province, Si Chomphu District, Wat Tham Saeng Tham , 16°50'31.0"N, 102°03'56.2"E, ca. 270 m. a. s. l., 27 May 2024. K. Srikampha coll. GoogleMaps • 6 ♂♂, 4 ♀♀ ( MZKKU), Khon Kaen Province, Si Chomphu District, Wat Tham Sing to Thong , 16°47'55.9"N, 102°02'49.3"E, ca. 360 m. a. s. l., 27 May 2024. K. Srikampha coll. GoogleMaps • ♀ ( MZKKU), Chaiyaphum Province, Khon San District, Mortagek Monastery , 16°30'17.0"N, 101°50'41.8"E, ca. 390 m. a. s. l., 16 July 2023. K. Srikampha coll. GoogleMaps • ♂ ( MZKKU), Chaiyaphum Province, Khon San District, Wat Tham Phaya Chang Phueak , 16°33'47.6"N, 101°51'36.3"E, ca. 320 m. a. s. l., 1 June 2024. K. Srikampha coll. GoogleMaps

Diagnosis.

S. petramurum sp. nov. differs in the femur of the legs, in which only the apical margin carries a few teeth (no teeth or teeth at the entire margin in the other known Sphaerobelum species), a character only shared with S. bicorne Attems, 1938 , S. bolavensis Wesener, 2019 , S. nonghinensis sp. nov., and S. onyx sp. nov. S. petramurum sp. nov. differs from both S. bicorne and S. bolavensis in the presence of a “ hook ” on telopoditomere 4 of the posterior telopods. S. petramurum sp. nov. differs strongly in the colouration from both S. nonghinensis sp. nov. and S. onyx sp. nov. (greenish-bluish brown vs. black).

S. petramurum sp. nov. shares only with S. clavigerum , S. hirsutum , S. laoticum , S. nonghinensis sp. nov., S. onyx sp. nov., S. schwendingeri , S. separatum , and S. splendidum the presence of a “ hook ” on telopoditomere 4 of the posterior telopods. This new species differs from S. clavigerum by having 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 also differs from S. laoticum and S. schwendingeri in the presence of apical dish carrying <60 apical cones and tergites greenish-bluish brown (vs. 81–86 in S. laoticum , 36–73 in S. schwendingeri , and tergites black), from S. splendidum in the presence of leg 2 with coxal process (vs. absent) and a long telopoditomere 2 of anterior telopod (vs. short, without process as long as telopoditomere 3), and from S. nonghinensis sp. nov. by having a greenish-bluish brown body colour (vs. almost black). It differs from S. onyx sp. nov. by the presence of 5–6 rows of marginal bristles and marginal bristles covering 3 / 4 of outer area (vs. 3–4 rows, 1 / 4 cover area).

Description.

Measurements: Male holotype; body length 29.1 mm, width (broadest) of thoracic shield 13.7 mm, of tergite 7 = 14.5 mm; height of tergite 7 = 8.5 mm. Males: body length = 25.7–25.9 mm; width (broadest) of thoracic shield = 13.0– 13.7 mm, of tergite 7 = 13.9–14.7 mm; height of tergite 7 = 8.3–8.9 mm. Females: body length = 29.7–30.5 mm; width (broadest) of thoracic shield = 14.5–15.3 mm, of tergite 7 = 15.3–16.2 mm; height of tergite 7 = 9.2–10.0 mm.

Colouration (Fig. 10 A – G View Figure 10 ): Specimens in life greenish-bluish brown or light brown, shiny. Head and collum brown to dark brown. Antennae, thoracic shield, paratergites, anal shield, legs, and venter light brown. Midbody area of each tergite with a longitudinal bluish-green or brown stripe (band), becoming visible when the animal rolls up. Lateral margin of each tergite with a brown patch. Anal shield with a large triangular brown patch. Specimens in alcohol after 3 years slightly faded to pale greenish-bluish brown.

Head (Fig. 11 A, E View Figure 11 ): Trapeziform; densely setose in anterior part and sparsely setose in posterior one; each seta located inside small pit. With 66–83 ommatidia (ocelli) in males and 54–79 in females. Aberrant ommatidium and organ of Tömösváry as in S. nonghinensis sp. nov. and S. onyx sp. nov.

Antennae (Figs 10 B, C View Figure 10 , 11 B – D View Figure 11 ): Quite short and slender; covered by long and dense setae; last antennomere reaching back to leg pair 2 or 3. Lengths of antennomeres 6> 1 = 2 = 3 = 4 = 5 Antennomere 6 rounded apically; oval; apically with sensilla basiconica. Apical disc slightly convex, with 49–56 apical cones in male or 27–32 in female.

Epipharynx (Fig. 11 F View Figure 11 ): With a regular central tooth (ct); laterally with numerous external teeth (et), short and sharp; inner area of each side with a row of delicately dentate spines (rsp).

Gnathochilarium (Fig. 11 G, H View Figure 11 ): Structure typical as for Sphaerotheriida . Lamellae linguales (ll) rectangular, apically truncate. Central pads (Cp) modified, with numerous sensory cones. Stipites (st) large; densely setose; located laterally to lamellae linguales. Mentum (me) large; fused at base; with dense and long setae. Lateral palpi inconspicuous. Inner palpi (ip) with sensory cones (sc) arranged in three fields (clusters).

Mandibles (gnathal lobe) (Fig. 11 I View Figure 11 ): With undivided external tooth (Et) and with conspicuous 3 - combed inner tooth (3 it). With 5–6 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) apically with two or three ridges.

Tegument (Fig. 10 A – G View Figure 10 ): Shiny; all tergites 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 10 B, C View Figure 10 , 11 A View Figure 11 ): Subsemicircular; tip of lateral margin obtuse; sparsely long setose at margin.

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: Slightly sexually dimorphic; large and well-rounded in female, slenderer in male. Underside with a single, black locking carina; twice as long as length of tergites.

Endotergum of midbody tergite (Fig. 14 E, F View Figure 14 ): Posterior margin (pm) unmodified, flat, regular. Outer area (oa) quite wide; smooth, without setae. Marginal bristles arranged in three or four rows; tips of the longest bristles not protruding above posterior margin. Middle area (ma) with a single row of conspicuous, wavy impressions; distance between impressions twice as long as individual diameter. Inner area (ia) without tubercles or setae.

Pleurites (laterotergites) (Fig. 12 D View Figure 12 ): First pleurite slender, boomeranglike; apical margin attenuated, strongly projecting into a wide tip. Pleurite 2 wider than the first one, protruding into obtuse tip. All remaining pleurites flat and broad, apical margin slightly extended.

Subanal plate (Fig. 12 H View Figure 12 ): Densely setose; broad and wide; subsemicircular; apical margin slightly concave.

Stigmatic plates (Fig. 12 C View Figure 12 ): First stigmatic plate trapeziform, apex rounded. Second stigmatic plate in both sexes not curved.

Legs (Fig. 12 A – G View Figure 12 ): All podomeres sparsely setose. Coxa (cx) large; coxal process absent in first legs; each side of legs 4–21 marginally with a large, dentate ridge. Prefemur (pre) quite short; apico-mesally with a weak projection. Femur (fe) 1.8 times longer than wide, with long ridge in all leg pairs; apico-mesally with inconspicuous dentate margin, carrying inconspicuous teeth (Sp). Postfemur (po) and tibia (ti) short. Tarsus (ta) of midbody legs quite long, 4 times longer than wide, as long as length of femur + postfemur; first two leg pairs without an apical spine; leg-pair 1 with 2 ventral spines; leg-pair 2 with 4 or 5 ventral spines; leg-pair 3 with 6 or 7 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. 12 F View Figure 12 ): Small, triangular; covered by long setae.

Anterior telopods (Fig. 13 A, C, E – G View Figure 13 ): First telopoditomere rectangular, slender, width <height. Telopoditomere 2 large, longer than telopoditomere 1. Immovable finger (process of telopoditomere 2) long and slender, longer than telopoditomere 3, clearly seen in posterior and ventral views, strongly curved; tip obtuse, apically with several sclerotised spots. Telopoditomere 3 longer than telopoditomere 4, distinctly demarcated from telopoditomere 4 by suture when seen in ventral view, apically with a single spine. Tepoloditomere 4 short, less than half as long as telopoditomere 3, with three spines (two spines located near base and one at apex); tip directed mesad.

Posterior telopods (Figs 13 A – D View Figure 13 , 15 I, J View Figure 15 ): Slender. Consisting of 4 telopoditomeres. First telopoditomere rectangular. Telopoditomere 2 large and long. Immovable finger (process of telopoditomere 2) long, hammer-like; 2 times longer than wide, with a characteristic, mesally swollen apex; tip obtuse, with thick and dark spot near apex; in-situ curving ventrad; antero-apical margin slightly collapsed to accommodate tip of telopoditomere 4; inner margin with single spine. Telopoditomere 3 quite short, 2 times longer than wide, with single spine at excavated inner margin. Telopoditomere 4 relatively short, 2 times shorter than telopoditomere 3, strongly tapering toward apex; slightly curved toward apex by forming a digitiform tip with two long spines. Telopoditomere 1 covered by setae. Telopoditomeres 2 with setae only in anterior view. Telopoditomeres 3 and 4 glabrous, except small area at basal part of telopoditomere 3. Inner horns with sharp-edged tips, slightly curved caudad.

Female sexual characters (Fig. 12 G View Figure 12 ): Vulva quite long and slender. Vulva large, slender; covering almost 1 / 3 of coxa; extending mesally to almost half of prefemur. Operculum (op) wide and slender; mesal margin strongly protruding into an obtuse lobe on each side. Bursa (bu) long and slender, demarcated from operculum by a triangular groove.

Etymology.

The name is a Latin noun, here in apposition, meaning “ rock wall, ” and refers to the preferred habitat of the new species found in limestone.

Distribution and habitat

(Fig. 10 H View Figure 10 ). Sphaerobelum petramurum sp. nov. is currently distributed in limestone borders of Chaiyaphum and Khon Kaen Provinces. Most specimens have been discovered exclusively in small crevices within rocky walls or beds in humid limestone evergreen forests. This unique habitat highlights the adaptation to its specific environment, where moisture and shelter are abundant, allowing it to thrive in these limestone-rich ecosystems.

Remarks.

The intraspecific genetic divergence (p - distance) of the COI fragment in the new species is high, ranging from 0 to 7.15 %, as observed between the populations of the Mortagek Monastery and others.

The majority of specimens display a greenish-brown body colour, while a minority exhibit a light brown colour, with both variants found within the same populations. Females are typically larger in size than males.