Magnacrus tongmianensis ( Zhu, Li & Song, 2002 ) Hoang & Yu & Wendt & West & Wirth, 2025

Magnacrus tongmianensis ( Zhu, Li & Song, 2002) gen. nov. comb. nov.

( Figs 1–4 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 , 13D View FIGURE 13 , 14 View FIGURE 14 , 17 View FIGURE 17 )

Citharognathus tongmianensis Zhu, Li & Song 2002: 371 View in CoL , figs 1, 2A–I; Schmidt 2003: 248, fig. A–E; Zhu & Zhang 2008: 425, figs 1A–I (females only).

Type materials. Holotype ♀ (MHBU-Ar. T0029 ) and paratype 1 ♀ (MHBU-Ar. T0030 ), CHINA: Guangxi, Ningming Co., Tongmian Township ( 21° 46’ N, 107° 19’ E), 15 January 2002, leg. Tinghui Li ( MHBU, examined). GoogleMaps

Other materials examined. 1 ♂ (TNU-THE-0005) & 1 ♀ (TNU-THE-0002), VIETNAM: Đắk Lắk Province : Ea Kar District, Cu Elang ( TNU), leg. Quang Duy Hoang ; 1♀, Vietnam ( SMF) ; 1 ♂ (SMNS-Aran-001565) & 4 ♀♀ (TNU-THE-0001, 0003, 0007; SMNS-Aran-001566), VIETNAM: Đắk Lắk Province , leg. Quang Duy Hoang.

Diagnosis. Females of Magnacrus tongmianensis can be easily distinguished from M. taynguyenensis gen. nov. sp. nov., by the following: (1) scopula on met. IV well developed and divided (fig. 2H in Zhu et al. 2002 and fig. 2F in Zhu & Zhang 2008) vs. weakly developed, undivided ( Fig. 13A View FIGURE 13 ); (2) stridulatory spines on the prolateral palp coxa with 17 spines in M. tongmianensis ( Fig. 1E View FIGURE 1 ) while 10 spines in M. taynguyenensis ( Fig. 7E View FIGURE 7 ); (3) the notch in the middle of the undivided spermatheca ( Fig. 1D View FIGURE 1 ) in the M. tongmianensis is shallow compared to M. taynguyenensis ( Fig. 7D View FIGURE 7 ). Palpal male of M. tongmianensis with 7 keels (PS, PA, PSA, PI, RB, A, SA) and a distinct VTM ( Fig. 3A–F View FIGURE 3 ) vs. five keels (PS, PA, PI, SA, A) and without VTM ( Fig. 6A–F View FIGURE 6 ) in M. taynguyenensis ; M. tongmianensis with two spines on the ventral tibia I apically ( Fig. 2D View FIGURE 2 ) vs. absent in M. taynguyenensis ( Fig. 5D View FIGURE 5 ); ERF in M. tongmianensis is ca. 33 ( Fig. 3F View FIGURE 3 ) while M. taynguyenensis is above 40 ( Fig. 6F View FIGURE 6 ).

Description of male (TNU-THE-005). Body length: 44.5 (including chelicerae).

Color (in life) ( Fig. 4B View FIGURE 4 ): Femora of legs dark brown, rest of front legs light brown, tips of metatarsi and tarsi dark brown. Legs dorsally with distinct elongated beige stripes. Carapace and abdomen brown.

Carapace ( Fig. 2A View FIGURE 2 ): length 17.0, width 14.5. Fovea low, Fovea: 1.87 wide, curve length 1.89, slightly recurved.

Chelicerae ( Fig. 2F View FIGURE 2 ): length 9.5, width 6.0. strong, reddish setal fringe along promargin.

Clypeus: width 0.63, smaller than width of OT.

Eyes: OT length 2.19, width 2.56. Anterior row almost straight, posterior row slightly procurved. Diameter (longitudinal) ALE: 0.62; AME: 0.68; PLE: 0.53, PME: 0.58; inter-distances: ALE – AME: 0.17; AME – AME: 0.33; PLE – PME: 0.03;

Maxillae ( Fig. 2E View FIGURE 2 ): length (incl. trochanter) 11.0. Prolaterally plano-convex, anterior prolateral lobe wellpronounced. Retrolateral face mostly glabrous. Prolateral face with a stridulating organ consisting of 20 thorn-like black spines pointing forward and increasing in length and size from posterior to anterior and dorsal to ventral, in three rows; of these, 4 small thorn-like spines are located between the actual spine arrangement and the suture. Fine plumose setae above suture intermixed with four longish spiniform setae, dorso-anterior edge with a row of elongated black spiniform setae.

Labium: length 2.87, width 1.81, wider posteriorly, anterior and posterior edge procurved. Many small black cuspules (~67).

Sternum ( Fig. 2B View FIGURE 2 ): length 8.09, width 6.70. Wider posteriorly than anteriorly, with a thin intermix of short setae and sparse longer setae, more so along edges. No spines on edges, but thicker setae along opposing edges of coxa IV. Sternal sigilla: three pairs (not including labio-sternal sigilla), glabrous, PSS largest, ovoid, length 0.80, 0.84 from sternum edge, 3.04 between PSS and clearly visible. Middle and anterior pair obscured by setae, middle pair smaller than PSS and anterior pair smaller than middle pair. Labiosternal groove: glabrous, slightly narrower medially, groove with low oblong cuticular mound on either side of medial narrowing.

Leg setation: all legs covered with short pile setae with scattered longer guard setae. Leg I & IV tibia with pro and retrolateral fringe of short pile setae.

Legs: formula I, IV, II, III. LRF~ 101. Leg lengths (fem., pat., tib., met., tar., total): I 16.5, 8.5, 16.0, 13.0, 9.5, 63.5. II 16.0, 6.5, 12.5, 11.5, 8.0, 54.5. III 13.0, 6.0, 9.0, 10.5, 9.0, 47.5. IV 17.0, 6.0, 15.0, 17.0, 8.0, 63.0. Tar. IV uniform without transverse pallid medial suture. Tibia apophysis on leg I ventral with a single prolateral apophysis with numerous spines at its tip ( Fig. 2C–D View FIGURE 2 ).

Scopula: met. I–III and tar. I – IV, undivided; met. IV divided. Met. I: 88%; II: 73%; III: 54%; IV: 41%.

Coxae: coxae I – IV covered ventrally with fine setae, intermixed with longer darker setae, apically, darker basally. Leg I almost as long as IV, 1.17 times the length of II. IV widest, not as rectangular as III. Prolateral margins of II–IV, retrolateral margins of I–IV and apical ventral margins of I–IV, increasing from anterior to posterior, with longer setae, absent along prolateral margin of I. Ventral measurements for coxa + trochanter: length: I 12; II 11; III 10; IV 11. Fine plumose setae on prolateral face, intermixed with numerous elongated black spiniform setae.

Spines: Leg: I Tib. 1 v, a, rl; 1 v, a, pl; Met. 1 v, a, pl; 1 v, a, m; II Tib. 1 v, a, rl; 1 v, a. pl; Met. 1 v, a, rl; 1 v, a, m; 1 v, a, pl; III Tib. 1 v, a, pl; 1 v, a, rl; Met. 1 d, a, pl; 1 d, a, rl; 1 v, a, pl; 1 v, a, m; 1 v, a, rl; IV Tib. 1 v, a, pl; 1 v, a, rl.; Met. 1 v, sm, pl; 1, v, a, pl; 2 v, a, m.; 1 v, a, rl.

Claws: all unarmed, no third claw on leg IV.

Abdomen: length 18.0, wide: 13.0

Palpal bulb ( Fig. 3A–F View FIGURE 3 ): Embolus with seven keels, PS, PA, PSA, PI, RB, A and SA keel, tegulum ventrally basal with a bulge-like process (VTM), ERF~ 33.

Spinnerets: PMS: length 0.98; PLS: length 5.42.

Additional description to female (TNU-THE-00002). Body length: 55 (including chelicerae).

Color (in life) ( Fig. 4A View FIGURE 4 ): Femora of legs dark brown, rest of front legs light brown, rear legs gray brown, carapace light beige, opisthosoma gray brown. Patella, tibia and metatarsus IV retrolaterally with a dense fringe of longer reddish setae. Femur I have a retroventral fringe of short dense red setae.

Carapace ( Fig. 1A View FIGURE 1 ): length 20.5, width 15.5. Fovea: 2.38 wide, 2.45 curved length, procurved.

Chelicerae ( Fig. 1F View FIGURE 1 ): length 11.0, width 4.0. Retrolaterally with a large field of plumose setae, baso-dorsally with a smaller field of strong plumose setae, baso-ventrally with 5 long, sword-shaped plumose setae.

Clypeus: width 0.8, clearly smaller than width of OT.

Eyes: OT length 2.20, width 3.12. Diameter (longitudinal) ALE: 0.81; AME: 0.73; PLE: 0.64, PME: 0.59; inter-distances: ALE – AME: 0.34; ALE – PLE: 0.24; PLE – PME: 0.15; PME – AME: 0.14; AME – AME: 0.41.

Maxillae ( Fig. 1E View FIGURE 1 ): length (incl. trochanter) 12.09. Prolaterally plano-convex, anterior prolateral lobe wellpronounced. Retrolateral face mostly glabrous. Prolateral face with 17 short thorn-like black spines pointing forward and increasing in length and size from posterior to anterior, in two rows, fine plumose setae above suture, dorso-anterior edge with a row of 11 elongated black spiniform setae.

Labium: length 2.34, width 2.83. 88 cuspules in anterior area of labium.

Sternum ( Fig. 1B View FIGURE 1 ): length 10.16, width 7.86. Wider posteriorly than anteriorly, with a thin intermix of short setae and sparse longer setae, more so along edges. No spines on edges, but thicker setae along opposing edges of coxa IV. Sternal sigilla: three pairs (not including labio-sternal sigilla), glabrous, PSS largest, ovoid, length 1.15, 0.77 from sternum edge, 3.53 between PSS and clearly visible. Middle and anterior pair obscured by setae, middle pair smaller than PSS and anterior pair smaller than middle pair. Labiosternal groove: glabrous, slightly narrower medially.

Leg setation: all legs covered with short pile setae with scattered longer guard setae. Leg IV patella, tibia and metatarsus with dense retrolateral brush of longer guard setae ( Figs 1C View FIGURE 1 , 4A View FIGURE 4 ).

Legs: formula IV, I, II, III. LRF~ 85. Leg lengths (fem., pat., tib., met., tar., total): palp 12.0, 7.0, 7.5, –, 7.5, 34; I 14.0, 8.0, 11.0, 8.0, 7.5, 48.5; II 12.0, 7.0, 8.0, 8.0, 6.5, 41.5; III 12.0, 6.5, 6.0, 7.5, 6.0, 38; IV 16.0, 8.0, 14.0, 13.0, 6.0, 57. Pat., Tib. + Met. of leg III and IV strongly incrassate. Tar. IV uniform without transverse pallid medial suture.

Scopula: met. and tar. I–IV, undivided. Met. I: 75%; II: 68%; III: 60%; IV: 45%.

Coxae: coxae I – IV covered ventrally with fine setae, intermixed with longer darker setae, apically, darker basally. Leg I almost as long as IV, 1.17 times the length of II. IV widest, not as rectangular as III. Prolateral margins of II–IV, retrolateral margins of I–IV and apical ventral margins of I–IV, increasing from anterior to posterior, with longer setae, absent along prolateral margin of I. Ventral measurements for coxae + trochanter: length: I–13; II–12; III–10; IV–13.

Spines: Palp Tib.: 1 v, a, rl; 2 v, a, pl; Leg: I Tib.: 1 v, a, pl; Met.: 1 v, a, m; II Tib.: 1 v, a, rl; Met.: 1 v, a, rl; 1 v, a, m; 1 v, a, pl; III Tib.: 1 v, a, rl; 1 v, a, pl; Met.: 1 d, a, rl; 1 d, a, pl; 1 v, a, rl; 2 v, a, m; IV Tib.: 1 v, a, rl; 4 v. a, pl (other Leg: 2 v, a, pl); Met.: 1 d, a, pl; 1 v, sm, pl; 1 v, m, pl (other Leg: 1 v, sm, pl; 1 v, sa, pl); 6 v, a, rl; 5 v, a, pl.

Claws: all unarmed, no third claw on leg IV.

Abdomen: length 20, wide: 20.

Genitalia ( Fig. 1D View FIGURE 1 ): Spermatheca undivided and consisting of two lobes connected by a dent in the middle. Width 4.11, height at the highest point of the left lobe 0.94, of the right lobe also 0.94, at the lowest point in the middle 0.63. The angle between the two lobes is 133.43°.

Spinnerets: PMS: 1.59; PLS: length 7.74.

Natural history. Specimens of M. tongmianensis were collected from low elevations (below 600 m elev.). The once existing tropical deciduous lowland forest in the region now consists mainly of agricultural development (corn, tangerines) with rubber plantations and small fragmented secondary forests ( Fig. 14A View FIGURE 14 ). The self-excavated fossorial retreats of M. tongmianensis were found on gently sloped ground amongst shaded vegetation in clay-like soil at the fringes of secondary forest or plantations at an elevation of 500 meters. Retreats of adult females averaged 5 cm in diameter and 40 cm in length and ran somewhat parallel under the ground surface, unbranched, curving upwards and ending in a blind chamber ( Fig. 14C View FIGURE 14 ). M. tongmianensis incorporates surrounding organic debris with silk around the entrance rim of the retreat. What is remarkable here is the arrangement of foliage and leaves around the burrow entrance. These are often arranged in such a way that rainwater flows past the burrow entrance due to the arrangement of the leaves and thus does not enter the burrow. A similar arrangement of leaves at the burrow entrance was observed with Cyriopagopus doriae (Thorell, 1890) in Borneo. There, too, rainwater was prevented from entering the burrows by the roof-like arrangement of leaves at the burrow entrance ( Koh 2024).

Occupied retreats are usually silken over by day, possibly to prevent predacious ants and wasps from entering ( Fig. 14B View FIGURE 14 ). When extracted from the retreat, M. tongmianensis will become very defensive and readily bite if further provoked ( Fig. 14D View FIGURE 14 ). Nothing is known about the life cycle of M. tongmianensis . Males were found wandering in July and it is suspected this is the breeding season for this species, during the highest rainy season from June through to the end of August in the Central Highlands of Vietnam (Q. D. Hoang & T. D. Nguyen, pers. obs.).

Ethnozoology. A local ethnic mix of Kinh and Mnong people call these spiders Nhện lông which means ‘hairy spider’ and treat them with mixed ideas. Some local people reported the venomous bite from this spider will kill a water buffalo, but without evidence, while other people collect, cook and eat these spiders (arachnophagy) with great appeal and as a supplement food source. Taylor (1975) investigated the nutritional values of the tarantula spiders eaten in Cambodia and Laos and found they were 63.4% protein and 9.8% fat by body weight. Further, a few village people reported they kill and soak these spiders in wine to make a traditional medicine for rubbing on their skin to cure aches, sprains and bruising (Q. D. Hoang, pers. obs.).

Distribution. China (?); Vietnam (Đắk Lắk) ( Fig. 17 View FIGURE 17 ).

Remark. The type locality of M. tongmianensis (Tongmian, China) and the newly reported locality here (Đắk Lắk Province, Vietnam) have a distribution gap of over 1,200 kilometers, which is extremely rare throughout the Theraphosidae . Đắk Lắk Province belongs to the Tây Nguyên Plateau in central Vietnam and represents a distinct biogeographic region. Although Đắk Lắk Province and Tongmian have roughly the same elevation, the annual precipitation, average temperature, and relative humidity in Đắk Lắk Province are much higher than those in Tongmian (Weather and Climate 2025). Moreover, from a biogeographic perspective, Tongmian is in southern China, where the fauna and flora closely resemble those of northeastern Vietnam (east of the Red River), but differ significantly from that west of the Red River, which is considered a natural biogeographic barrier ( Averyanov et al. 2003; Sterling et al. 2006; Bain & Hurley 2011; Hoang 2025). These facts make the disjunct distribution of this species even more difficult to explain.

Tongmian Township, located on the China-Vietnam border, has served as a major transit hub in the cross-border tarantula trade between China and Vietnam for the past two decades. Collectors, after gathering spiders in Vietnam, would converge on Tongmian before shipping their acquisitions, with a single shipment sometimes containing thousands of individuals ( Hu et al. 2009). M. tongmianensis was one of the species caught up in this trade. According to private communications between Yu and a local collector in Tongmian, M. tongmianensis were actually collected around the area of Buôn Ma Thuột City in Vietnam (pers. comm. Yu and local collectors in Tongmian). Moreover, during five separate fieldwork expeditions undertaken by Yu in Tongmian in recent years, not a single specimen of M. tongmianensis was found, and no further information on the species in China has been reported anywhere. Based on the above, we suspect that the type specimens of M. tongmianensis ( two females) might have been escaped individuals during the smuggling process and was collected by chance. This species may not have a natural population in China. Its natural population might be endemic to the Central Highlands region of Vietnam.