Nepalmatoiulus immaturus, Mikhaljova, 2020

Mikhaljova, Elena V., 2020, New data on the fauna of China, part I: the taxonomy of the millipede family Julidae (Diplopoda), Zootaxa 4729 (1), pp. 47-66 : 61-65

Nepalmatoiulus immaturus new species

Figs 68–76

Material examined: Holotype: subadult male (= “junior male”) ( ZMUM), China, Yunnan Province, N Weixi, ridge Mekong & Luozhua, 4.4 km N of Maliping , 27°41´26´´ N, 99°0´56´´ E, H = 2985 m asl., 23.05.2016, leg. I. Kabak, G. Davidian ; Paratype: 1 female ( ZMUM), same locality as in holotype, 23.05 2016, leg. I. Kabak, G. Davidian.

Diagnosis. Differs from congeners mainly by the configuration of the posterior gonopod solenomere with a long subapical branch, coupled with the shape of mesomeral process supplied with papillar knobs.

Description. Subadult male (= “junior male”). Length 26–27 mm, vertical diameter about 2.5 mm, with 54 (–3) rings, excluding telson. Coloration in alcohol marbled brown with relatively broad longitudinal dark brown lateral and dorsal stripes. Axial suture dark brown. Venter including legs light brown. Dorsal parts of legs marbled brown. Collum with two large transversely-oval, marbled brown spots. Head marbled brown excluding light brown ventral part and dark brown strip between eyes. Antennae brown, eyes black. Head smooth, 2 epicranial setae, 4 supralabral setae, many labral setae broken. Eye patches almost oval, composed of about 50 ocelli. Antennae medium-sized, rather slender and clavate; length and width ratios of the antennomeres as in majority of Nepalmatoiulus . Gnathochilarium apparently without nonapical stipital setae. Mandibular stipite with small subtriangular (i.e. underdeveloped) lobe; 6 setae on each lamella linguales. Collum laterally with several distinct long lower striae extending from posterior to anterior margin, dorsally with short striae at posterior margin only. Length of the collum striae gradually decreasing toward dorsum. A transverse row of sparse setae at hind edge of collum. Body rings circular. Prozona smooth. Metazona with dense, regular, longitudinal striae reaching hind margin (10–11 striae in an approximate square with sides equal to metazonital length of a dorsal side of midbody ring). Limbus straight, smooth (of Type 1 in Enghoff 1987). The metazonite gradually growing narrower toward ventral part of body. A transverse row of thin setae at hind edge of metazonites, setae gradually growing denser toward telson. Ozopores small, lying behind suture dividing pro- and metazona, set off from the suture. Telson with caudal dorsal projection long, covered with dense setae and carrying at tip a claw-shaped small process directed caudad. Preanal ring, anal valves, and subanal scale densely setose. Legs relatively short and slender, pregonopodal and most hind legs devoid of ventral adhesive pads. But very narrow ventral pads present on postfemur and tibia of mid-body legs. Claw of all legs at base with a relatively long (longer than claw) setiform accessory claw ventrally but without accessory claw dorsally. Leg pair 1 normal, i.e. underdeveloped ( Fig. 68 ).

Coxa 2 with two mesapical oral setae, without gland opening ( Fig. 69 ). Penis oblong oval, with apical excavation ( Fig. 74 ). Ventral margin of body ring VII with ventrad subtriangular apically rounded lobes. Gonopods slightly protruding. Anterior gonopod flattened, with parallel margins, apically obliquely rounded, in posterior view apically excavated for accommodation of mesomeral process, distal margins of the excavation papillate, subcentrally with knoblike flattened rudimentary telopodite ( Figs 70, 72 ). Flagellum slender, of medium length, covered with cuticular conical subobtuse denticles in the distal part; basal part of the flagellum caudally covered with cuticular spikes. Opisthomere with moderately large mesomeral process, its apex with papillar knobs; velum steeply sloping, its margin smooth; additional membrane with a smooth edge ( Figs 71, 75 ). Solenomere densely spinose throughout, subapically with long spinose branch (b) ( Figs 71, 73 ) (apex of a flagellum (f) is visible in the figures 71, 73).

Female. Length 33–34 mm, vertical diameter about 3.0 mm, with 54 (–1) rings, excluding telson. Coloration darker than in male. Vulva as in Fig. 76 ; apical lobes of bursa relatively long, posterior median plate with a more than 20 setae arranged more or less regularly.

Remarks. The holotype has fully developed gonopods and penis but unmodified leg pair 1 and underdeveloped mandibular stipites; in addition, it is lacking leg ventral adhesive pads. It is a subadult male or “junior male” in terms by Strasser (1971). Similar subadult males (i.e. males with fully formed gonopods but with unmodified leg pair 1) are not unusual in the Julidae ( Enghoff et al. 1993) . I do not consider this male as an “intercalary male”, its presence among the material cannot be accepted as evidence of periodomorphosis because an intercalary male must have been preceded by a copulatory one, i.e. stadium and name be defined by ontogeny ( Enghoff et al. 1993). In addition, phenomenon of periodomorphosis was not found in Nepalmatoiulus ( Enghoff 1987) .

The reason that I venture to describe the new species in spite of the absence of adult male is that I believe that the gonopods of N. immaturus sp. nov. are fully developed and will not be changed in the future. Therefore, their structure is a reliable distinguishing character.

Etymology: The specific epithet refers to the holotype - subadult male.

Figures

FIGURES 68–76. Nepalmatoiulus immaturus sp. nov., subadult male holotype and female paratype. 68, leg pair 1, front view; 69, leg pair 2, front view; 70, promere, caudal view, flagellum broken; 71, opisthomere, mesal view; 72, promere apex, caudal view; 73, solenomere apex with distal part of promere flagellum; 74, penis, front view; 75, apex of opisthomere mesomeral process; 76, vulva, caudal view; b, solenomere subapical branch; f, flagellum apex. Scales: 10 μm (Figs 72, 75), 20 μm (Figs 73–74), 100 μm (Figs 68–71, 76).