Unixenus moniqueae, Huynh, 2020

Huynh, Cuong, 2020, Three new species of penicillate millipedes from the Con Dao Islands of southeast Vietnam (Diplopoda, Lophoproctidae and Polyxenidae), Zootaxa 4759 (1), pp. 1-30 : 21-23

publication ID

https://doi.org/ 10.11646/zootaxa.4759.1.1

publication LSID

lsid:zoobank.org:pub:8C3F94C9-3923-43F4-918A-6A1CA92F1F49

DOI

https://doi.org/10.5281/zenodo.3811987

persistent identifier

https://treatment.plazi.org/id/03C287E9-8602-FFE3-FF40-FE575726FF25

treatment provided by

Plazi

scientific name

Unixenus moniqueae
status

sp. nov.

Unixenus moniqueae View in CoL new species

Fig. 17–21 View FIGURE 17 View FIGURE 18 View FIGURE 19 View FIGURE 20 View FIGURE 21

Material examined: Type specimens. Adult ♂ holotype ( QMS 109028),; 6 adult ♀ paratypes ( QMS 109029–34) from Vietnam, Con Dao archipelago, Con Son Island, Lo Voi beach, leaf litter in casuarina woodland, 8.691097°N, 106.620542°E, elevation 9 m; on 24th July 2015 (Collected by C. Huynh).

Diagnosis. Shares similar characteristics with U. mjoebergi and U. intragramineus : chaetotaxy (setae on leg articles) with one seta on pre-femur and two setae on femur, single seta on tibia and tarsus 2. Claw more similar to U. intragramineus in being slender, differs from U. mjoebergi . A posterior process shorter than half length of the claw in U. moniqueae compared to U. intragramineus with a posterior process longer than half length of the claw.

Description: Colour dark brown patch in eye area, same colour as transverse band in vertex. Body milky white, light brown pleural trichomes and darker colour in caudal bundle; dark brown marks on lateroposterior rosette trichomes form a dark band along each lateral side of body. Last tergite darkest in colour; white ventrally ( Fig. 17 View FIGURE 17 ). Holotype, body length 2.2 mm; paratypes 2.2–2.4 mm. Male caudal bundle slightly narrower in width and longer (0.6 mm) compared to female (0.5 mm). Head: Each side with 8 ommatidia: 4 dorsal, 4 lateral (1 anterior, 2 medial and 1 posterior). Vertex with 2 posterior trichome groups with a large medial gap, each group with 2 rows. Anterior row curved slightly on an oblique angle, all trichome sockets of similar size, posterior row with varied trichome socket sizes. A narrow space between anterior and posterior rows. Holotype with vertex posterior trichome groups with 14+12 sockets in anterior rows and 8+6 sockets in posterior rows ( Fig. 18A View FIGURE 18 ) (Variations are common in paratypes regardless of sex, from 12–18 sockets (anterior rows) and 6–10 (posterior rows)) ( Fig. 19A View FIGURE 19 ). Trichobothria: trichobothrium a (posterior position), trichobothrium b (lateral position) and trichobothrium c (anterior position) typically thin sensory hairs with narrow cylindrical funicles. Trichobothria (a, b and c) equal in socket size, forming an isosceles triangle with equal distance between ab and bc ( Figs 18F View FIGURE 18 and 19C View FIGURE 19 ). Antennae: 8 antennomeres, 4 sensory cones ( Fig. 20A View FIGURE 20 ), typical characteristics of Polyxenidae . Antennomere VI with 3 thick bacilliform sensilla (T), different lengths: A short bacilliform sensillum located in the anterior position (Ta), the longest intermediate long bacilliform sensillum (Ti), and a bacilliform sensillum of (Tp) medium length in posterior position. A setiform sensillum (s) between Ta and Ti and conical sensillum (c) in next to Tp. Antennomere VII with 2 thick bacilliform sensilla, Ta slightly longer than Tp; a setiform sensillum (s) between them and a conical sensillum (c) located next to Tp ( Fig. 20B View FIGURE 20 ). (This pattern of sensilla on the antennomere VII is commonly seen in all Unixenus species). Clypeolabrum: Holotype with 10 setae along labrum posterior margin, these setae being half the width of labrum (setae in paratypes ranging from 10–13 in both sexes). Labral surface with spherical papillae with pointed ends, forming 3 rows of large size setae in anterior margin and reducing in size in posterior margin. Anterior margin of labrum with 4+4 lamellae on each side of median cleft ( Figs.18G View FIGURE 18 and 19B, D View FIGURE 19 ). Gnathochilarium: Lateral palp 2.5 times as long as medial palp. 13 conical sensilla on lateral palp, medial palp with 22, same in holotype and paratypes ( Fig. 18H View FIGURE 18 ). Trunk: 10 tergites, 9 pleural projections, and telson excluding caudal bundle.13 pairs of legs. Collum (tergite 1) with trichome sockets arranged in 2 oval shapes in lateral position, opposite each other connected by a posterior row of trichome sockets forming a line with a gap in the middle. Holotype collum with 49 trichome sockets both sides, lateral protuberances with 5 trichome sockets on each side ( Fig.18B View FIGURE 18 ) (Trichome sockets on collum varying in paratypes ranging from 54–60 sockets and 4–5 sockets on lateral protuberances). Tergites 2–10, each with pleural projections located in anterolateral positions. Tergal trichome socket arrangements from tergites 2–9 typically with 4 undefined rows of tergal trichomes arranged in two lateroposterior clusters, on either side of midline. Anterior row often uneven, intermediate rows rarely in defined rows and posterior row of trichomes continuous and evenly distributed, forming a line with a medial gap ( Fig. 19A View FIGURE 19 ). Tergite 10 is the exception, with trichome sockets being smaller and denser. Almost no space between lateral rosette trichome sockets and those in posterior row. Trichome sockets of tergite 2 in holotype with 55 on both sides ( Fig. 18C View FIGURE 18 ). Tergite 10 with 53 (L) and 54 (R) sockets ( Fig. 18D View FIGURE 18 ) (In contrast, trichome sockets on tergite 2 in paratypes 50–65, whereas tergite 10 containing between 54–68 trichome sockets). Legs: Leg segmentation following Manton (1956). Legs 1 and 2 without trochanter, leg 1 lacking tarsus 1. Chaetotaxy (setae on leg articles): coxa 1: 1 seta, coxa 2: 2 setae, coxae 3–13: 2–6 setae; pre-femur, tibia and tarsus 2 with seta; femur with 2 setae ( Fig. 21A View FIGURE 21 ). Setae on coxa, pre-femur, femur distally with with longitudinal ridges on basal funicle; each ridge extending distally into long thin spine, spines surrounding flagellum base ( Fig. 21B View FIGURE 21 ). Seta in mid femur similar, but smaller ( Fig. 21C View FIGURE 21 ), tibia and tarsus 2 each with setiform seta ( Figs. 21D and E View FIGURE 21 ). Posterior edge of last sternite with 4 setae similar those present on coxa (Number of these setae same in paratypes). Sex organs in male: pair of penes present on coxa 2, 2 pairs of coxal glands on coxal plates of legs 8th and 9th. Telotarsus-Claw: A slender structure bearing a posterior lateral process that is shorter by half the length of claw. A small anterior lateral process and a lamella process both present, anterior setiform process slightly enlarged at base and longer than the claw ( Fig. 21F View FIGURE 21 ). Telson: Dorsal ornamental trichome sockets arranged symmetrically on both side of telson with 5 trichomes a sockets in holotype (Paratypes with 5–6 trichomes a). A single trichome b socket and 3 trichome c with large protruding base sockets: c 1, c 2 and c 3, forming a triangular shape each side of telson. Circular indentation d apparent near exterior side of trichomes c ( Fig. 18E View FIGURE 18 ). Caudal bundles: Male, caudal bundle with a single uniform large trichome socket of caudal trichomes. Female with two obvious distinguishing structures: a main dorsal structure similar to male, but with 2 latero-sternal bundles of smaller trichome sockets of nest trichomes ( Figs. 19E, F View FIGURE 19 ). Caudal trichomes 2–4 hooks. (These caudal structures are like those observed in U. intragramineus ( Huynh and Veenstra 2018c) which is common to members of the genus Unixenus and is classified as caudal bundle type I ( Condé and Nguyen Duy-Jacquemin 2008))

Remarks: Unixenus moniqueae n. sp. was first identified as Unixenus sp. by Monique Nguyen Duy-Jacquemin and Condé (1967) based on two adult specimens (a male and a female), which were collected from Con Son Island, Vietnam. These specimens were part of the Indochinese collections of Dr C. Dawydoff ( Attems 1938). Formal naming of these specimens was deferred because of uncertainty around the specific diagnosis of Unixenus at that time, despite this species having similar characteristics to U. mjoebergi and other evidence that supported them belonging to the same genus ( Nguyen Duy-Jacquemin and Condé, 1967). The identification of Unixenus to species proved difficult due to similarities in the morphology of the main characteristics used for identification: the sensilla on antennomere VI, pointed spherical papillae of the labrum, 13 sensilla on the lateral palp of gnathochilarium, the arrangement of the tergal trichome sockets, chaetotaxy and the setiform sensillum on tarsus 2.

Etymology: The species is named in honour of Dr. Monique Nguyen Duy-Jacquemin who made a significant contribution to the study of penicillate millipedes since the 1960s. She was the first to identify this species collected from Con Son Island, Con Dao Islands in 1967 as Unixenus sp.

Kingdom

Animalia

Phylum

Arthropoda

Class

Diplopoda

Order

Polyxenida

Family

Polyxenidae

Genus

Unixenus

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