Euscorpiidae Laurie, 1896

Teruel, Rolando, Kovařík, František, Lowe, Graeme & Šťáhlavský, František, 2023, Two new species of the remarkable scorpion genus Megacormus Karsch, 1881 (Scorpiones: Euscorpiidae), Euscorpius 375, pp. 1-22 : 4

Family Euscorpiidae Laurie, 1896 Megacormus Karsch, 1881

( Figures 1–82 , Tables 1–3)

Megacormus Karsch, 1881: 16–18 ; Soleglad, 1976: 263–264; Francke, 1979: 223–230, figs. 1–6; Sissom, 1994: 265– 271, figs. 1–10; Fet & Sissom, 2000: 377–378 (complete references list until 2000); Soleglad & Sissom, 2001: 25–111, figs. 10, 20, 55, 64, 81, 88, 107, 120–122, 135, 142, 153–154, 161–162, 167, 173, 182, 194, 205–215, 218, tables 2, 3, 5, 6, 9–10; Soleglad & Fet, 2003b: 7, 11, 61, 66– 68, 88, 105, tabs. 3–4, 9; KovařÍk, 2009: 32; Zárate-Gálvez & Francke, 2009: 342–343, fig. 15; González -Santillán & Alvarez-Padilla, 2015: 75–91, figs. 1–28; Santibáñez-López et al., 2016: 6; González-Santillán et al., 2017: 221– 237, figs. 1–13, table 1; Santibáñez-López et al., 2017: 95; KovařÍk, 2019: 1–46, figs. 1–215, table 1; KovařÍk et al., 2020b: 30; OlguÍn-Pérez et al., 2021: 98–106, figs. 1–5

TYPE SPECIES. Scorpio granosus Gervais, 1843 .

DIAGNOSIS. Carapace densely granulose, trapezoidal, anterior margin weakly emarginate; 2–4 pairs of lateral eyes, eyespot present. Dorsal dentate margin of cheliceral movable finger armed with two relatively large, subequal subdistal denticles; ventral dentate margin with 1–4 smaller, subequal denticles on its distal half, the most distal denticle always present and largest. Pedipalp patella with well-developed dorsal patellar spur, small or vestigial ventral patellar spur. Dentate margins of pedipalp chela fingers with median denticles arranged contiguously in a linear series extending the length of the finger, divided into subrows by slightly enlarged denticles; each enlarged median denticle (MD) closely flanked by one enlarged outer denticle (OD), one enlarged inner denticle (ID), and one enlarged inner accessory denticle (IAD) (transverse denticle group of 4); numerous additional, smaller outer accessory denticles together form a sparser, secondary linear series extending the length of the finger; a smaller number of additional inner accessory denticles also present, mostly on proximal finger. Trichobothrial pattern type C, neobothriotaxic majorante on pedipalp patella: external series 17–23 (7 eb, 2 esb, 2–5 em, 3–5 est, 3–4 et); ventral series, 5–10. Legs without tibial spurs, tarsi with two pedal spurs. Sternum type 2, hexagonal in shape. Hemispermatophore lamelliform, trunk broad, with truncal flexure; convex aspect of capsule with proximal and distal transverse ridges, each terminating anteriorly in sclerotized apophyses; basal carina elongate with sclerotized crown-like structure. Sternite VII and metasoma I–V with single prominent ventromedian carina. Telson without subaculear tubercle.

SUBORDINATE TAXA.

Megacormus franckei KovařÍk, 2019

Megacormus gertschi DÍaz Nájera, 1966

Megacormus granosus (Gervais, 1843)

Megacormus grubbsi Sissom, 1994

Megacormus orizaba sp. n.

Megacormus seductus sp. n.

Megacormus segmentatus Pocock, 1900

Megacormus xichu González-Santillán et al., 2017

DISTRIBUTION. Mexico (Guanajuato, Hidalgo, Oaxaca, Puebla, Querétaro, San Luis PotosÍ, Tamaulipas, and Veracruz) .

Figures

Figures 1–2. Megacormus seductus sp. n., male holotype (1) and female paratype with a juvenile (2) in vivo habitus.

Figures 3–6: Megacormus seductus sp. n. Figures 3–4. Male holotype in dorsal (3) and ventral (4) views. Figures 5–6. Female paratype in dorsal (5) and ventral (6) views. Scale bars: 10 mm.

Figures 7–16: Megacormus seductus sp. n., male holotype, pedipalp chela dorsal (7), external (8) and ventral (9) views, patella dorsal (10), external (11) and ventral (12) views, femur and trochanter dorsal (13) and ventral (14) views, movable (15) and fixed (16) fingers dentition. Movable finger (15) is under UV light, other figures are under white light.

Figures 17–26: Megacormus seductus sp. n., female paratype, pedipalp chela dorsal (17), external (18) and ventral (19) views, patella dorsal (20), external (21) and ventral (22) views, femur and trochanter dorsal (23) and ventral (24) views, movable (25) and fixed (26) fingers dentition.

Figures 27–34: Megacormus seductus sp. n. Figures 27–28. Male holotype, carapace and tergites I–IV (27) and coxosternal area and sternites (28). Figures 29–34. Female paratype, carapace and tergites I–IV (29), coxosternal area and sternites (30), and left legs I–IV, retrolateral aspect (31–34).

Figures 35–42. Megacormus seductus sp. n. Figures 35, 37–39. Male holotype, telson in lateral (35), metasoma and telson in lateral (37), dorsal (38) and ventral (39) views. Figures 36, 40–42. Female paratype, telson in lateral (36), metasoma and telson in lateral (40), dorsal (41) and ventral (42) views. Scale bars: 10 mm (37–39, 40–42).

Figure 43. Megacormus seductus sp. n., habitat at type locality.

Figures 62–65. Hemispermatophores of Megacormus spp. Figure 62. M. orizaba sp. n. 19MD (holotype, No. 1621). Figure 63. M. granosus (No. 2462). Figures 64–65. M. seductus sp. n. 22MA (holotype and paratopotype, Nos. 2460, 2461).Convex views of left hemispermatophores (62, 63) and right hemispermatophores shown in mirror image (64, 65). Scale bars: 500 μm.

Figures 66–77. Hemispermatophore capsules of Megacormus. 66. M. orizaba sp. n. (holotype, No.1621). 67–68. M. gertschi (Nos.1619, 1620).69. M. franckei (paratype, No. 1618).70–71. M. xichu (Nos.1617, 1626).72–73. M. seductus sp. n. (holotype and paratopotype,Nos.2460–2461).74. M. segmentatus (No.1622).75. M. granosus (No.2462).76. M. grubbsi (No.1623).77. M. grubbsi (No.2463).Convex views ofleftcapsules (66, 68–71, 73–75 and 77), and right capsules shown in mirror image (67, 72 and 76).Abbreviations: dpd, distal dentate process; dpp, proximal dentate process; cls, crown-like structure; trd, distal transverse ridge; trp, proximal transverse ridge; tmsd, terminal membrane of the sperm duct. Scale bars: 400 μm.

Figures 78–81. Chromosomes of Megacormus species. 78–79. M. seductus sp. n. (No. 2461) (2n=109). 80. M. segmentatus (No. 1262) (2n=144). 81. M. granosus (No. 2462) (2n=148). Postpachytene (78 and 80), one sister metaphase II (79), ane mitotic metaphase (81). Arrowhead shows trivalent in postpachytene. Scale bar: 10 μm.

Figure 82. Distribution of Megacormus specimens examined for this review (see Comparative material examined in Methods, Material & Abbreviations section).