Brachycybe disticha, Mikhaljova, Elena V., Golovatch, Sergei I., Korsós, Zoltán, Chen, Chao-Chun & Chang, Hseuh-Wen, 2010

Mikhaljova, Elena V., Golovatch, Sergei I., Korsós, Zoltán, Chen, Chao-Chun & Chang, Hseuh-Wen, 2010, The millipede order Platydesmida (Diplopoda) in Taiwan, with descriptions of two new species, Zootaxa 2718, pp. 51-63 : 52-57

Brachycybe disticha sp. nov.

Figs 1–16, 18 .

Material examined. Holotype: male (NMNS-6459-001, D-0027), Taiwan, Nantou County, Huisun timberland, 12 November 1997, leg. S. H. Wu. Paratypes: 5 males (one dissected for SEM: anterior and posterior body parts, midbody segment, gonopods), 4 females ( IBSS), 1 male, 1 female ( ZMUM), 1 male, 2 females (NSYSUB), 5 males, 11 females, 1 juvenile (NMNS-6459-002, D-0027), same locality, together with holotype, 12 November 1997, leg. S. H. Wu; 1 male (NMNS-6459-003, D-0159), same locality, 27 December 1997, leg. S. H. Wu; 2 males (NMNS-6459-004, D-0158), same locality, 8 February 1998, leg. S. H. Wu; 1 female ( HNHM, No. 157), Taiwan, Nantou County, Ren-ai Township, Meifeng, 24°06’ N, 121°12’ E, 2300 m, 5–6 September 2003, leg. G. Csorba & Z. Korsós; 1 female ( HNHM), Taiwan, Nantou County, Ren-ai Township, Wushe, western slope of Meifeng, 24°04.913’ N, 121°09.434’ E, 1659 m, disturbed secondary broad-leaved forest, 13 October 2009, leg. L. Dányi & E. Lazányi; 1 female (NMNS-6459-005), Taiwan, Nantou County, Shueili, Renluen biodiversity project, 1600 m a.s.l., Cryptomeria plantation (plot E10–2), May 2006, leg. Tunghai University Spider Research Group; 1 male, 3 females (NMNS-6459-006), Taiwan, Nantou County, Shueili, Renluen, experimental forest area, primary forest, 23°42.5’ N, 120°55.3’ E, 1615 m, 15 May 2008, leg. L. Dányi, Z. Korsós & E. Lazányi; 1 female ( HNHM), Taiwan, Nantou County, Shueili, Renluen, experimental forest area, primary forest, 23°42.7’ N, 120°56.2’ E, 1901 m, 16 May 2008, leg. L. Dányi, Z. Korsós & E. Lazányi; 4 males, 2 females ( HNHM), Taiwan, Pingtung County, Mutan, 8 December 1998, leg. Gy. Fábián & Z. Korsós; 3 males (NSYSUB, 0002), Taiwan, Pingtung County, Shizi Township, Neiwen, under rotten wood, 5 October 2002, leg. S. Y. Wu. Non-type: 1 male (NSYSUB), Taiwan, Kaohsiung County, Lioguei, Shanping Workstation, May 2004, leg. M. J. Hung.

Diagnosis. This species differs from congeners mainly by the collum showing three rows of tubercles, by distinct paranota on the collum directed anterolaterad, in the presence of six apical stylets on the posterior gonopods, in the steep lateral slopes of the dorsum and in the large, mid-dorsal tubercles forming two evident paramedian rows virtually all along the body.

Description. Male. Length mainly ca 8.5–15.0 mm, width ca 2.7–4.1 mm together with paranota, 33–47 body segments including telson. Body length of most of males 12–14 mm, width ca 4.0 mm, with 41 or 44 body segments. Holotype 15 mm long, 4.0 mm wide, with 47 segments including telson. Male from Kaohsiung County 20.5 mm long, 4.7 mm wide, with 53 body segments including telson, being distinguished not only by its considerably larger size, but also due to its peculiar collum (see below). Coloration in alcohol: dorsum light

tan with paraterga growing lighter distad; ventral side of body and legs yellowish white; head yellowish or white. Coloration of younger, smaller individuals lighter to pallid.

Head moderately densely setose. Collum with distinct paranota directed anterolaterad ( Fig.1 ). Three rows of tubercles on each side of collum: anterior row with 1–2 tubercles, middle and posterior rows with 3–4 tubercles, these varying in size with paramedian ones being larger.

Body covered with dense minute pubescence. Slopes of dorsum steep, so body in cross-section subtriangular ( Fig. 2 ). Paranota 2–4 narrower than following ones, their lateral margins being rounded ( Fig. 3 ). In Fig. 3 , anterior body end inclined somewhat caudad, yet difference between shapes of paranota 2–4 and of following ones more drastic than shown in Fig. 3 . Lateral paranotal margin of remaining segments with a small notch ( Fig. 4 ). Midbody segments with two rows of tubercles on metazona, caudal row shorter and extending to base of paranota; anterior row longer, extending to about midlength of paranota. Paramedian tubercles considerably larger. Mid-dorsal tubercles on all segments combined forming two distinct paramedian rows extending all along body ( Fig. 15 ). Paranota curved strongly anteriad on segments 2–5, increasingly less so on segments 6–10(11), slightly curved caudad on segment 11(12) and following segments; caudal curvature of paranota increasingly clear on 6–7 posteriormost segments in front of telson; paranota of penultimate segment produced strictly caudad and flanking telson ( Fig. 5 ). Caudal paranotal margins entire, without notches.

Legs slender, shorter than segment width together with paranota, terminating before lateral paranotal margins. Claws normal.

Two pairs of gonopods directed anteriad. Anterior gonopods ( Figs 6, 7 , 12 & 13 ) 7-segmented, covered with long setae. Coxite broad. Podomere 2 short. Each of following podomeres (3–6) with a medial protuberance carrying strong setae. Ultimate podomere excavated centrally to accommodate stylets of posterior gonopod. Posterior gonopods ( Figs 8, 9 & 14 ) 7-segmented, covered with sparse long setae. Coxite broad. Ultimate podomere longest, with six prominent, parallel, apical or subapical stylets of varying length. Each stylet with triangular spur subapically and group of minute batons near middle. Gonopod sterna with low papillae and two apical setae.

Female. Length ca 14–18.5 mm, width 3.9–4.8 mm together with paranota; 44–48 body segments including telson. Most of females with bodies 15–17 mm in length, ca 4.5 mm in width, with 44 or 47 body segments. Nonsexual characters as in male. Anterior body end and collum as in Figs 10 & 11 .

Juvenile. Length ca 9.0 mm, width 2.5 mm together with paranota; 29 body segments including telson.

Name. The specific epithet refers to two parallel rows of larger mid-dorsal tubercles along the axial line.

Remarks. The holotype of Brachycybe nodulosa ( Verhoeff, 1935) , the type-species of Bazillozonium Verhoeff, 1935 , the latter genus being a junior synonym of Brachycybe ( Gardner 1974/75), was revised for comparative purposes. Bazillozonium nodulosum was originally described from Beppu, Oita Prefecture, Kyushu, Japan but, according to Shelley et al. (2005), following Moritz & Fischer (1974) and a personal communication from S. Friedrich (ZSM), the reference to Beppu as being located near Tokyo, Honshu Island, Japan as given by Verhoeff (1935) is a mistake. Beppu in fact borders on Oita City. A side-by-side comparison of both these species revealed them to differ considerably. Thus, B. disticha shows the collum supporting three rows tubercles and broader anterolateral lobes ( Figs 1 , 11 ), as opposed to two rows and narrower lobes in B. nodulosa . In addition, in B. disticha the slopes of the dorsum are steep ( Fig. 16 ), so the body in crosssection looks subtriangular ( Fig. 2 ), whereas in B. nodulosa the dorsum is flatter ( Fig. 17 ) and similar to a rounded arch in cross-section. Besides this, the paramedian mid-dorsal tubercles in B. disticha are much larger and placed closer to each other, thus forming two evident longitudinal rows extending all along the body ( Fig. 15 ). In contrast, the paramedian mid-dorsal tubercles in B. nodulosa are smaller and more widely separated, not composing evident longitudinal rows. Furthermore, the body in B. disticha is broader than that of B.

nodulosa . This is clear from pictures ( Figs 16 & 17 ) taken from body fragments of both these species using specimens with about the same number of segments: 47 in B. disticha ( Fig. 16 ), and 50 in B. nodulosa , according to Verhoeff (1935) ( Fig. 17 ).

Both differ also in the number of apical stylets on the posterior gonopod: six in B. disticha versus four in B. nodulosa . The legs of B. disticha are slightly shorter than in B. nodulosa as well.

The male from Kaohsiung County, treated here as a non-type, is peculiar, differing from the other presumed conspecific samples of B. disticha from Taiwan in being 20.5 mm long, 4.7 mm wide, showing 53 body segments including the telson, and the collum rather resembling that of B. nodulosa , i.e. narrower anterolateral lobes and two rows of tubercles only on the right side of this tergite ( Fig. 18 ). On the left side, the front row of tubercles is irregular, forming a group of tubercles. Yet, the front row of tubercles on the collum of the sample from Kaohsiung County appears to continue the inner edge of the collum’s lobe, this being characteristic of male B. disticha from the other places, whereas in B. nodulosa the front row of tubercles on the collum is not located in continuation of the inner edge of the lobe. As regards the remaining characters, including gonopod ones, this male from Kaohsiung County fails to differ from B. disticha . Considering the importance of collum structure in the identification of Brachycybe species ( Shelley et al. 2005), we are inclined to treat the male from Kaohsiung County as representing B. disticha . However, more material is required to reveal the variation range of this species.

Figures

FIGURES 1 – 9. Brachycybe disticha sp. nov., male paratype. 1, collum, dorsal view; 2, midbody ring, cross-section; 3, anterior part of body, dorsal view, slightly skewed backwards; 4, midbody segments, dorsal view; 5, hind part of body, dorsal view; 6, anterior gonopods, front view; 7, left anterior gonopod, front view; 8, posterior gonopods, front view; 9, apex of posterior gonopod.

FIGURES 10 & 11. Brachycybe disticha sp. nov., female paratype. 10, anterior part of body, dorsal view; 11, collum, dorsal view.

FIGURES 12 – 14. Brachycybe disticha sp. nov., male paratype. 12, left anterior gonopod, front view; 13, right anterior gonopod, caudal view; 14, right posterior gonopod, front view. Scale in mm.

FIGURES 15 – 18. Brachycybe disticha sp. nov., male paratype (15); Brachycybe disticha sp. nov., fragment of a male paratype (16); Brachycybe nodulosa, fragment of male holotype (17); Brachycybe disticha sp. nov., collum of the male from Kaohsiung County (18). Photograph not to scale.