Hyleoglomeris tongkerdae Likhitrakarn, 2024

Likhitrakarn, Natdanai, Jeratthitikul, Ekgachai, Sapparojpattana, Pichsinee, Siriwut, Warut, Srisonchai, Ruttapon, Jirapatrasilp, Parin, Seesamut, Teerapong, Poolprasert, Pisit, Panha, Somsak & Sutcharit, Chirasak, 2024, Six new species of the pill millipede genus Hyleoglomeris Verhoeff, 1910 (Diplopoda, Glomerida, Glomeridae) in Thailand revealed by DNA-barcoding, Contributions to Zoology 93 (4), pp. 289-323 : 311-314

Hyleoglomeris tongkerdae Likhitrakarn ,

Sutcharit & Panha, sp. n.

Figs 11, 12

Holotype ♂ ( CUMZ-GLO071 ), Thailand, Lampang Province, Mae Mo District, Ban Thali , elev. ca. 350 m a.m.s.l., 18°26’16“N, 99°45’24”E, 20/09/2022, leg. N. Likhitrakarn and P. Jirapatrasilp.

Paratypes. 32 ♂♂, 53 ♀♀, 6 Juveniles ( CUMZ-GLO071 ) , 2 ♂♂, 6 ♀♀ ( MUC-GLO071 ), same locality, together with holotype .

Name. To honour Assistant Professor Dr. Piyoros Tongkerd, malacologist and lecturer at the Faculty of Science at Chulalongkorn University, who participated in collecting many millipede specimens, including the type series of this new species.

Diagnosis. Its color pattern is similar to that of Hyleoglomeris bomba sp. n., but differs in the colour of the venter and legs in comparison to the background colour of the dorsum [contrasting yellowish or paler hue (fig. 11G), vs matching (fig. 9E)]. the number of ommatidia [6(7)+1, vs 8 + 1)], coupled with the shape of the femoral process (fp) [subtriangular (fig. 12D), vs narrowed subtrapeziform (fig. 8D)].

Description. Body length of unrolled holotype, 6.9 mm, width 3.7 mm. Body length of unrolled paratypes, 5.8–7.8 mm (♂), 5.2– 7.5 mm (♀), width 3.4–4.2 (♂), 2.1–4.2 mm (♀).

Colour of live animals (fig. 11A–E): Body dark brown to light reddish brown, with contrasting pale yellow to yellow bands at posterior edges of terga 3–11, width of bands approximately 1/3–2/3 height of each tergum, axial stripe vivid yellow, complete and connecting terga 3 and 4, subsequently diminishing in length through following terga (fig. 11A, B); thoracic and anal shields (= pygidium) yellowish to light yellow (fig. 11A, B, C, E). Head, collum and antennae dark brown; labrum and Tömösváry’s organ brownish; collum with a narrow, contrasting yellow band at caudal edge; venter and legs brown to light brown with claws and posterior parts of each tarsus pale yellowish. Colour faded after one year of preservation in alcohol (fig. 11F–H), body of preserved specimens dark brown to pale brown, with contrasting pale yellow to whitish bands. Head and antennae grey to black; venter and legs pale brown to yellow-brown (fig. 11G).

Labrum sparsely setose (fig. 11G). Gnathochilarium with 2 + 2palps of equal length. Eyes blackish, with 6(7)+1 ommatidia, cornea very convex and translucent. Antennae with four evident apical cones, antennomere 6 approximately 2.2–2.4 times as long as its height (fig. 11A, B, G). Tömösváry’s organ typical, horseshoe-shaped, suboval, approximately 1.4–1.7 times as long as its width (fig. 11G).

Collum normal, with two transverse striae. Thoracic shield with a small hyposchism field not projecting behind tergal margin (fig.11A,H). Striae 7–9, mostly superficial, only lower 3–4 lying above schism,one level to schism,remaining 3–4 below schism, 5–6 complete and crossing the dorsum. Terga 3 and 4 broadly rounded laterally (fig. 11A, H). Following terga in front of pygidium faintly concave medially at caudal edge and with two or three striae starting above lateral edge, sometimes first stria fading out at midway. Pygidium very faintly concave medially at caudal edge (fig. 11F).

♂ legs 17 (fig. 12A) simple, strongly reduced, with a small to moderately sized, often rounded coxal lobe (cxl) and a 4-segmented telopodite.

♂ legs 18 (fig. 12B) simple, slightly reduced, without any evident outgrowths; Syncoxite membranous, with a simple, small and narrowly ogival syncoxite notch (sn) and a 4-segmented telopodite.

Telopods (= ♂ legs 19) (fig. 12C–E) with a small, subrectangular and rounded syncoxite lobe (sl) flanked by two long, spiniform, setose syncoxite horns (sh), these being noticeably higher than syncoxite lobe (fig. 12C–E). Telopodite 4-segmented, with a spine apically. Prefemur (fig. 12C) subrectangular, with a distinctive, elongated, robust, tuberculiform, distomesal prefemoral trichostele (pft); in caudal view with a rounded tip, extending to approximately half to distal boundary of femur (fig. 12C). Femur (fig. 12C, D) subtrapeziform, with a prominent, stout, relatively short femoral trichostele (ft). in caudal view extending apically to approximately 1/2–3/4 length of prefemoral trichostele (pft), and in caudal view with a rounded, subtriangular femoral process (fp) curved anterolaterally and gently tapering into an acuminate tip pointing distally (fig. 12D). Tibia relatively strongly elongated, gently tapering distally and curved basad towards femoral process, with a small, distolateral tibial process (tp) strongly curved mesad (fig. 12C, D). Tarsus the smallest, subcylindrical, moderately sigmoid, strongly curved, narrowly rounded apically, with a robust and small terminal seta (fig. 12C, D).

DNA barcode. The interspecific COI divergence between H. tongkerdae sp. n. and the nearest species, H. bomba sp. n., amounts to 10.77% (table 2).

Remarks. During a field survey at high humidity, hundreds of H. tongkerdae sp. n. millipedes were observed to crawl out and disperse throughout the limestone cliffs, with a nearly 1:1 sex ratio. Even though this new species shows a colour pattern similar to that of H. bomba sp. n., they are clearly distinct morphologically, especially their colour patterns, and the collection localities are approximately 100 km apart. In addition, the distinction in the molecular data strongly supports the validity of this species.