Glyphiulus formosus ( Pocock, 1895 )

Jiang, Xuan-Kong, Hennen, Derek A., Chen, Hui-Ming & Xie, Zhi-Cai, 2020, First description of the male of Glyphiulus formosus (Pocock, 1895) (Diplopoda Spirostreptida: Cambalopsidae) from China, Zootaxa 4861 (2), pp. 281-289 : 282-288

Glyphiulus formosus ( Pocock, 1895)

( Figures 1 ‒22)

Cambalomorpha formosa Pocock, 1895: 364 ; Attems, 1914: 295.

Glyphiulus formosus Mauriès, 1970: 513 , 517; Mauriès, 1977: 246; Wang & Mauriès, 1996: 85; Jeekel, 2004: 52; Golovatch et al., 2007a: 11; Golovatch et al., 2007b: 418; Jiang et al., 2018: 156.

Material examined. Near-topotypes: 4 males, 10 females and 3 juveniles, China, Guangdong Province, Shenzhen City, Tanglangshan Suburb Park , 22°34’17” N, 113°58’44” E, alt. 270 m, 13 October 2018, X.K. Jiang and H.M. Chen leg. ( IBGAS) .

Diagnosis. This species belongs to the G. javanicus group, and it can be separated from other species from this group except for G. recticullus Zhang & Li, 1982 and G. calceus Jiang et al., 2018 by (1) the crests on collum complete and developed, carinotaxic formula I–III + P + M; (2) male legs I two-segmented, obviously shorter than coxosternal process; (3) coxite process of anterior gonopod prolonged and axe-shaped; (4) male femora VI and VII slightly inflated. G. formosus is very similar to G. recticullus , but it can be distinguished by the flagellum of the posterior gonopod being incurved. G. formosus can be diagnosed from G. calceus by (1) coxite process of anterior gonopod relatively broader and shorter; (2) flagellum of posterior gonopod more slender; (3) male femora VI and VII slightly inflated, whereas they are unmodified in G. calceus .

Description. Body size ca. 27–35 mm long and 1.6–2.0 mm wide. Body rings with 52–58p + 4–2a + T.

Color. Generally orange-yellow ( Fig. 1 ); epicranium purple ( Fig. 2A ); clypeus and labrum cream; color of collum and subsequent two rings variable, from cream ( Figs 1 , 2 A–B) to fuscous; one thin, purple dorsal median line ( Figs 1A , 2C ) and two purple lateral bands ( Figs 1 , 2 B–F) extending from fourth ring to the last ring of trunk; the lateral band covering the ozoporiferous tubercles to the lateralmost crests ( Figs 1B , 2D ); telson light yellow ( Fig. 2 E–F); antennae purple ( Fig. 2 A–B); legs cream-colored ( Fig. 1B ).

Head. Each eye patch with 10–12 pigmented ommatidia arranged in two irregular linear rows ( Figs 2 A–B, 3A–B). Antennae stout. Antennomeres V expanded distally ( Figs 2B , 3B ). Antennae apical cones obvious (3 cones lost in Fig. 5A ). Clypeus with four teeth medially ( Fig. 4A ). Gnathochilarium with a separate promentum, oligotrichous ( Fig. 4A ). Mandibular gnathal lobe with a large external tooth and three small internal teeth ( Fig. 5B ).

Collum. All crests on collum complete and fully developed, carinotaxic formula I–III + P + M ( Figs 2 A–B,

3A–B). Body rings. Postcollum constriction modest ( Fig. 1A ). Tegument rough. Front of prozonae delicately al- veolate-areolate. Posterior parts of prozonae with fine longitudinal striations separated by smooth areas. Metazonae with engraved reticulate pattern ( Fig. 3 A–E). Metatergal crests well-developed ( Figs 2 B–G, 3A–E). Crests divided into two transverse rows of tubercles, carinotaxic formula 2/2+I/i+3/3+I/i+2/2 ( Figs 2 B–D, 3B–D). Ozoporiferous tubercles with rounded tip, larger than other tubercles. Lateral crests rather small, about 1/3 size of ozoporiferous tubercles ( Figs 2 B–D, G, 3B–D, 5D). Midbody rings round in cross-section ( Figs 2G , 5D ). Limbus with two rows of fine and regular denticulation ( Fig. 5 E–F).

Telson. Epiproct simple, with a rounded caudal ridge and a sharp dorsal tooth ( Figs 2 E–F, 3E). Paraprocts convex, polytrichous ( Figs 2F , 3F ). Hypoproct crescent-shaped ( Fig. 3F ).

Walking legs. Slender, slightly longer than body width, with a small accessory claw present at base of claw ( Figs 4 G–H, 5D).

Male sexual characters. Male legs I strongly reduced to two-segmented appendages, with a pair of medial coxosternal hooked processes in contact medially ( Fig. 4B ). Male legs II normal. Penes small ( Fig. 4C ). Male legs III modified, with coxa especially slender and elongated ( Fig. 4D ). Femora VI and VII slightly inflated distoventrally ( Fig. 4 E–F). Anterior gonopods. Coxite shield-like, ridged medially, creating a slight depression in caudal view, with a line of microsetae at the distolateral margin ( Fig. 6A ). Coxite processes slightly flattened, prolonged, axe-shaped, slightly longer than telopodites, with a few long setae at the medial margin ( Fig. 6A ). Telopodites located laterally on coxite, one-segmented, slender, curved, with slight apical indentation distomedially and slightly expanded at base, and with several distal setae and a field of microsetae at base ( Fig. 6A, C ). Posterior gonopods. Coxite with a medial lamelliform lobe and a row of strong, curved setae at mediolateral margin ( Fig. 6B ). Flagella short, incurved and sawtooth-shaped at inner margin, situated at the tip of coxite lobe ( Fig. 6B, D ). Lateral margin of coxite with a field of microsetae ( Fig. 6D, E ).

Vulvae. Simple, medial margin with a slightly laterally extended tip ( Fig. 5C ).

Ecology. These millipedes were found under rocks and rotten logs in a deciduous forest ( Fig. 7 ). Some specimens have been parasitized by ectoparasitic fungi in the order Entomophthorales ( Fig. 2A ), resembling its cavernicolous congener G. latus (see Jiang et al. 2017: fig. 2D).

Distribution. China: Hong Kong and Guangdong (Shenzhen).

GenBank accession numbers. MN905178 – MN905180 .

Notes. Our specimens agree with all the characters described for G. formosus in its original description, except the number of body rings and body size. The holotype has 72 body rings (number of podus and apodus rings unknown) and is about 50 mm long, whereas the largest specimen in our collection has 60 body rings (58 podus rings and 2 apodus rings) and is 35 mm long. The type of anamorphosis in Cambalidea was deduced to be euanamorphosis ( Enghoff et al. 1993), that means the cambalids can successively molt in its entire lifetime, and every molt is accompanied by the addition of new body rings and length. Indeed, large intraspecific variation in adult ring number is known in the Cambalidea, with differences of up to 35 rings reported ( Enghoff et al. 1993). Therefore, the holotype having more rings and being longer in body length likely indicates a stadium older than our specimens. Based on the near identical somatic morphology, the very close geographic locality, and the fact that there is no other species reported from this area (or even the whole province), we confidently report our specimens as the species G. formosus .

This species was known only from the original description and a brief redescription based on a female holotype, collected in 1892 ( Pocock 1895, Mauriès 1970). No further specimens have been reported since, until now with the 17 we collected for this study. Here, we have described the male of this species for the first time and solved this 125 years mystery.

The most important feature to distinguish the two groups of Glyphiulus , the G. granulatus group and the G. javanicus group, is the morphology of male legs I ( Golovatch et al. 2012, Jiang et al. 2017). However, lacking information on the male morphology, G. formosus was tentatively assigned to the G. javanicus group based on the similarity to G. mediator Attems, 1938 , in that they share the same carinotaxic patterns ( Mauriès 1970, Golovatch et al. 2007b). Our discovery clearly shows the characters of male legs I, and verifies its current taxonomic placement in the G. javanicus group.

The DNA barcodes of three specimens of G. formosus were successfully obtained, with the final length of 635bp. The pairwise intraspecific distances calculated based on Kimura 2-parameter model were 0% and 1.76%, respectively. The interspecific distances between G. formosus and G. sattaa were 23.98%, and between G. formosus and G. duangdee were 26.42% and 26.65% ( Table 1 ).

Figures

FIGURE 1. Somatic morphology of Glyphiulus formosus (Pocock, 1895). A. specimen in vivo; B. alcohol-preserved specimen. Scale bar: 2 mm.

FIGURE 2. Morphological characters of Glyphiulus formosus (Pocock, 1895). A. Head and anterior part of body, anterior view, arrow indicates the presence of ectoparasitic fungi, order Entomophthorales; B. same, lateral view; C. midbody rings, dorsal view; D. same, lateral view; E. posterior part of body, dorsal view; F. same, lateral view, arrows indicate the dorsal tooth of epiproct; G. cross-section of a midbody ring, caudal view. Scale bars: A–D, 0.5 mm; E–F, 0.2 mm; G, 0.5 mm.

FIGURE 3. Morphological characters of Glyphiulus formosus (Pocock, 1895). A. anterior part of body, dorsal view; B. same, lateral view; C. midbody rings, dorsal view; D. same, lateral view; E. posterior part of body, dorsal view; F. same, ventral view. Scale bars: A–D, 1 mm; E–F, 0.5 mm.

FIGURE 4. Male of Glyphiulus formosus (Pocock, 1895). A. gnathochilarium, ventral view; B. legs I, caudal view; C. legs II, caudal view; D. leg III, caudal view; E. leg VI, caudal view; F. leg VII, caudal view; G. midbody leg, caudal view; H. same, claw. Abbreviations: cs, coxosternum; csp, coxosternal process; cx, coxa; p, penis; t, telopodite. Scale bars: A–G, 0.2 mm; H, 0.05 mm.

FIGURE 5. Morphological characters of Glyphiulus formosus (Pocock, 1895). A. tip of antenna; B. mandibular gnathal lobe, anterior view; C. vulvae, caudal view; D. cross-section of a midbody ring, caudal view; E. limbus; F. same, zoom-in. Scale bars: A–B, 0.2 mm; C, 0.3 mm; D, 1 mm; E, 0.02 mm; F, 0.004 mm.

FIGURE 6. Male of Glyphiulus formosus (Pocock, 1895). A. anterior gonopods, caudal view; B. posterior gonopods, caudal view; C. microsetae at base of telopodites of anterior gonopods; D. flagellum of posterior gonopods; E. microsetae at lateral margin of posterior gonopods. Abbreviations: c, coxite; cp, coxite process; f, flagellum; l, lamelliform lobe; t, telopodite. Scale bars: A, 0.2 mm; B, 0.1 mm; C, 0.01 mm; D, 0.05 mm; E, 0.02 mm.

FIGURE 7. Microhabitat of Glyphiulus formosus (Pocock, 1895). A. typical deciduous forest habitat of G. formosus. B. flipped stone in same habitat. Arrow indicates one G. formosus revealed from under the stone.