Integrative data reveal a new millipede species of Sinocallipus Zhang, 1993 (Callipodida, Sinocallipodidae) from Vietnam, with notes on its phylogeny Author Nguyen, Anh D. 0000-0001-9273-0040 Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology, 18, Hoangquocviet Rd., Caugiay District, Hanoi, Vietnam & Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18, Hoangquocviet Rd., Caugiay District, Hanoi, Vietnam Author Stoev, Pavel 0000-0002-5702-5677 National Museum of Natural History, Bulgarian Academy of Sciences, Tsar Osvoboditel Blvd. 1, 1000 Sofia, Bulgaria & Pensoft Publishers, Prof. G. Zlatarski Str. 12, Sofia, Bulgaria Author Vu, Tam T. T. 0000-0003-1145-975X Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology, 18, Hoangquocviet Rd., Caugiay District, Hanoi, Vietnam & Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18, Hoangquocviet Rd., Caugiay District, Hanoi, Vietnam text Zoosystematics and Evolution 2025 2025-01-06 101 1 69 80 journal article 10.3897/zse.101.138716 0F9E72F6-2E43-4B0B-9BAD-29F2EF728396 Genus Sinocallipus Zhang, 1993 Figs 1 A – D , 10 Sinocallipus Zhang, 1993: 129 . Type species: Sinocallipus simplipodicus Zhang, 1993 , by original designation. Sinocallipus catba Stoev & Enghoff, 2011 . Sinocallipus catba : Stoev & Enghoff, 2011: 16 . Material examined. Vietnam • 2 ♀♀ ; Hai Phong Province , Cat Ba National Park , Trung Trang Cave ; 20.7887°N , 106.9980°E ; May 2012 ; Anh D Nguyen leg.; IEBR-Myr 542 . Diagnosis. Although only female specimens were collected and examined in the present study, the identity of the species is clear and well-supported. S. catba can be distinguished from its congeners by its white-yellowish body (Fig. 1 A ), a black eye composed of more than 30 ommatidia (Fig. 1 B ), and long antennae that extend beyond the posterior edge of pleurotergite (= PT) 7 when folded backwards. It also has 5 + 5 crests between the ozopores on midbody pleurotergites (= PTs), a gonocoxal process g that is approximately 1.5 × the length of process k , and paraprocts divided into larger ventral and smaller dorsal sclerites (Fig. 1 C ; Stoev and Enghoff 2011 ). The females studied here have well-developed, highly elevated cylindrical cyphopods (Fig. 1 D ). Figure 1. Sinocallipus catba Stoev & Enghoff, 2011 . ♀, IEBR-Myr 542 A. Anterior part of body, lateral view; B. Head and ocelli, lateral view; C. Telson, ventral view; D. Cyphopods and leg 2, anterior view. Abbreviations: pa = paraprocts; hy = hypoproct; cy = cyphopods. Scale bars: 1 mm. Remarks. The species is currently known from three caves on Cat Ba Island: Hoa Cuong Cave and Tien Duc Cave ( Stoev and Enghoff 2011 ), and Trung Trang (present study).