Betaburmesebuthus muelleri Lourenço, 2015

XUAN, QIANG, CAI, CHEN-YANG & HUANG, DI-YING, 2023, Revision of palaeoburmesebuthid scorpions in mid-Cretaceous amber from northern Myanmar (Scorpiones: Buthoidea), Palaeoentomology 6 (1), pp. 64-101 : 88-91

Betaburmesebuthus muelleri Lourenço, 2015

( Figs 19–21 )

Material. NIGP 201156, one probable juvenile female.We assume this specimen is a female based on its relatively wide carapace, short pectinal teeth and relatively robust metasoma.

Diagnosis (emended). This species can be clearly distinguished from other congeners by the following set of characters: 1) anterior margin of carapace with a moderately marked median concavity ( Fig. 20A, B ; Lourenço, 2015a); spiracles round to oval ( Fig. 20E ; Lourenço, 2015a: fig. 5); 3) pectines with 14–15 teeth ( Fig. 20E, G ; Lourenço, 2015a: fig. 3); 4) vesicle pearshaped and slightly dilated, and aculeus very long and strongly curved, base of aculeus wide ( Fig. 20I ; Lourenço, 2015a: fig. 6); 5) dorsal patellar spur carina with 3–4 small tubercles and without strong tubercles ( Fig. 21A, B, D ; Lourenço, 2015a: figs 3, 4); 6) Chela manus without spinous tubercles on internal surface ( Fig. 21A, B ; Lourenço, 2015a: fig. 3); 7) telotarsus with few ventrosubmedian setae and a ventromedian spinules row ( Fig. 20L, M ).

Description. Carapace. Sparsely covered by fine granules and posterior furrow evident ( Fig. 20A ); median eyes oval and medium sized, and separated by more than one ocular diameter ( Fig. 20A ); lateral eyes unclear except ADMi ( Fig. 20C ).

Coxosternal region ( Fig. 20E ). Surface smooth with several setae; anterior margin of coxapophysis I rounded; lateral margin of sternum relatively short as long as posterior margin; genital operculum composed of two completely separately oval valves, elongated in horizontal direction.

Chelicerae. With setae on internal surface; cheliceral dentition partly visible ( Fig. 20B ), including a long dorsal distal (dd) denticle, a small subdistal (sd) denticle and a stout median (m) denticle.

Pedipalps. Femur with five carinae ( Fig. 21A, B, D ): internomedian carina well-developed with about six small tubercles; other dorsointernal carinae relatively smooth. Patella with seven carinae observed ( Fig. 21A, B, D ): Dorsal Patellar Spur carina (DPSc), dorsointernal, dorsomedian and dorsoexternal carinae. Chela relatively slender (Cl/Cw = 6.41, Table 1 ); each finger denticle row consisting of about 10–14 (first row with 5) granules and a thick and short seta present beneath each accessory granule.

Trichobothrial pattern ( Fig. 21 ). Femur with 10 trichobothria, 5 dorsal, 3 internal and 2 external trichobothria, trichobothrium d 2 straddling dorsointernal carina and trichobothrium e 1 proximal to trichobothrium d 5. Patella with 10 trichobothria observed, including 5 dorsal (d 2 petite), 1 internal and 4 external trichobothria; trichobothrium d 3 internal to dorsomedian carina and trichobothrium d 4 external to dorsomedian carina. Fixed finger with 1 internal, 3 external, and 2 dorsal trichobothria observed. Chela manus trichobothria not visible.

Legs. Prolateral and retrolateral pedal spurs present on all legs. Ungues moderately long, dactyl pointed ( Fig. 20L, M ).

Pectines ( Figs 2K , 5B ). Basal piece with a small anterior median notch ( Fig. 20F ). Pectines with about 3 marginal lamellae and at least 7 median lamellae; fulcra not evident. Few sensory hairs extending from surface of lamellae. Teeth moderately long and terminal one ovoid, peg sensillae not very clear.

Mesosoma. Tergites unclear. Sternites covered by sparse setae ( Fig. 20E ).

Metasoma ( Figs. 1A, B , 5C, D, E ). Relatively robust, metasoma I length approximately equal to its width, other segments longer than width, metasoma V relatively short (length ratio (met V/met IV) = 1.19), all segments covered by macrosetae ventrally. Segments I–III with week depression dorsally; dorsal carinae on segments I–IV slightly serrated, other carinae smooth to serrated.

Telson ( Figs 5E , 6I ). Surface rugged, a small subaculear tuberance observed. Vesicle/aculeus juncture very wide and equal to half of vesicle.

Figures

FIGURE 1. General habitus of Betaburmesebuthus bellus, NIGP200648, under incident light. A, Dorsal view. B, Ventral view. Scale bars = 1 mm.

FIGURE 2. Details of Betaburmesebuthus bellus, NIGP200648, under confocal microscopy with depth color-coding. A, Carapace. B, Lateral ocelli. C, Coxapophysis, coxa and trochanter of leg I. D, Sternum and genital operculum. E, Spiracle of sternite VI. F, Tergites I–VI. G, Dentition of movable finger. H, Dentition of fixed finger. I, Tibial spur of leg III. J, Tibial spur of leg IV. K, Left pectine. L–O, Telotarsi of legs I–IV.Abbreviations:ADMi, anterodorsal minor ocellus; ALMa, anterolateral major ocellus; MLMa, mediolateral major ocellus; PDMi, posterodorsal minor ocellus; PLMa, posterolateral major ocellus; sp, spiracle; ts, tibial spur. Scale bars = 200 μm in A, F, G, K; 100 μm in C, D, E, H, I, J, L, M, N, O; 50 μm in B.

FIGURE 5. Details of Betaburmesebuthus bellus, NIGP200649, under green epifluorescence. A, Carapace and tergites. B, Coxosternal region, pectines and sternites. C, Metasomal segments I–IV, ventral view. D, Metasomal segments I–IV, dorsal view. E, Metasomal segment V and telson, lateral view. F, Tibial spur of leg III. G, Tibial spur of leg IV. H, Telotarsus of leg III. I, Telotarsus of leg IV. Abbreviations: ts, tibial spur. Scale bars = 400 μm in A–E; 100 μm in F–I.

FIGURE 6. Details of Betaburmesebuthus bellus, NIGP200649, under confocal microscopy. A, Carapace. B, Lateral ocelli. C, Chelicerae, dorsal view. D, Chelicerae, ventral view. E, Coxosternal region. F, Genital operculum and basal piece. G, Spiracles. H, Dentition of movable finger. I, Telson. J, Tibial spur of leg III. K, Tibial spur of leg IV. L, Telotarsi of leg IV. M, Telotarsi of leg III. Abbreviations:ADMi, anterodorsal minor ocellus; ALMa, anterolateral major ocellus; MLMa, mediolateral major ocellus; PDMi, posterodorsal minor ocellus; PLMa, posterolateral major ocellus; sp, spiracle; st, subaculear tubercle; ts, tibial spur. Scale bars = 200 μm in A, E, G, H; 100 μm in C, D, F, I, J, K, L, M; 50 μm in B.

FIGURE 19. General habitus of Betaburmesebuthus muelleri, NIGP201156, under incident light. A, Dorsal view. B, Ventral view. Scale bars = 1 mm.

FIGURE 20. Details of Betaburmesebuthus muelleri NIGP201156, A, D, E, F under green epifluorescence; B, C, F, G, I–M under confocal microscopy. A, Carapace and tergites. B, Chelicerae, dorsal view. C, Lateral ocelli. D, Tergite VII and metasomal segments I–IV, dorsal view. E, Coxosternal region, pectines and sternites. F, Sternum and genital operculum. G, Pectine. H, Tergite VII and metasomal segments I–IV, ventral view. I, Telson. J, Tibial spur of leg III. K, Tibial spur of leg IV. L, Tarsus of leg I. M, Tarsus of leg IV.Abbreviations:ADMi, anterodorsal minor ocellus; sp, spiracle; st, subaculear tubercle; ts, tibial spur. Scale bars = 400 μm in A, D, E, H; 100 μm in B, F, G, I–M; 50 μm in C.

FIGURE 21. Trichobothrial pattern of Betaburmesebuthus muelleri NIGP201156, A, B under green epifluorescence; C, D under confocal microscopy. A, Left pedipalp, dorsal view. B, Left pedipalp, ventral view. C–D, Left chela, dorsal view. E. Left femur and patella, dorsal view. Scale bars = 400 μm.