Delarthrum telnovi, Gordana & Ambros, 2023

Golovatch, S. I., 2023, On several new or poorly-known Oriental Paradoxosomatidae (Diplopoda: Polydesmida), XXXI, Arthropoda Selecta 32 (1), pp. 1-14 : 8-12

Delarthrum telnovi sp.n.

Figs 20–57 , 59, 60 .

MATERIAL. HOLOTYPE ♂ ( ZMUM), Western Nepal, Karnali Prov., Humla Distr. , ca 12–13 km SE of Simikot, N 29º54′23″– 29º54′00″, E 81º55′7″–81º55′11″, 2990–3310 m a.s.l., disturbed mixed forest, 17–18.VI.2022, D. Telnov leg.

PARATYPES (often fragmented): 3 ♂♂ ( ZMUM), same place, together with holotype; 2 ♂♂, 4 ♀♀ ( ZMUM), same province and district, 12–13.5 km SE of Simikot, Ghatte , Yanchu Khola to Simikot , N 29°54′23″–29°53′37″, E 81°55′7″–81°55′36″, 2920– 3490 m a.s.l., pasture and disturbed mixed forest, 18.VI.2022; 2 ♂♂, 1 ♀ ( LNDM), 1 ♀ ( ZMUM), same province and district, 13.5– 13.9 km SE of Simikot ( Fig. 59 ), N 29°53′37″–29°53′16″, E 81° 55′36″–81°55′31″, 3445–3880 m a.s.l., primary montane forest, 19.VI.2022; 1 ♀ ( ZMUM), same province and district, 34.5 km SE – 41 km E of Simikot ( Fig. 60 ), N 29°45′10″–29°41′47″, E 82°4′26″–82°6′4″, 1655–3525 m a.s.l., disturbed montane forest, 23.VI. 2022 all D. Telnov leg.; 2 ♂♂ ( ZMUM), same province, Mugu Distr. , Rara National Park, 30–31 km NNW of Jumla, N 29º32′43″–29º32′16″, E 82º7′32″–82º4′34″, 3290– 2940 m a.s.l., old-growth montane forest, 28.VI.2022, D. Telnov & K. Greķe leg.; 1 ♂, 1 ♀ ( ZMUM), same province, Jumla Distr. , 14 km NE– 9 km NNW of Jumla, N 29°23′43″–29°21′26″, E 82°8′55″–82°9′31″, 2770–3550 m a.s.l., disturbed montane Quercus forest, 1.VII.2022, D. Telnov leg.

DIAGNOSIS. Differs from all congeners by the solenophore (sph) being unusually hypertrophied, long and slender, directed and almost fully to fully coiled mesad, bearing a large to very large lateral membranous lobe (lo) near base. It is D. furcatum ( Golovatch, 1996) , from the Kathmandu Valley, that seems to be particularly similar to D. telnovi sp.n., as it shows basically the same gonopodal conformation [ Golovatch, 1996, 2014], including a long distofemoral spine and a curved solenophore. Yet D. furcatum differs readily by the more strongly developed paraterga, the prominent process o on the gonofemorite and, above all, the much shorter solenophore. See also Remarks below.

NAME. Honours Dmitry Telnov, the main collector.

DESCRIPTION. Holotype ca 22 mm in length (♂), midbody pro- and metazonae 1.7 and 2.0 mm in width, respectively (♂). Paratypes 18–23 mm long (♂, ♀), 1.7–2.2 and 2.0–2.5 mm (♂) or 1.8–2.7 and 2.0–2.9 mm (♀) wide on midbody pro- and metazonae, respectively.

Coloration in alcohol usually uniformly dark chocolate brown to brown, only venter and legs lighter brown (sometimes almost contrasting paler), tip of antenna pallid, gonopods yellowish ( Figs 20, 21 , 28–31 , 37–39 , 45–47 , 51–54 ).

Body with 20 rings, ♂ submoniliform. Clypeolabral region of head densely setose, vertigial region with a few setae only; epicranial suture fine, but distinct ( Figs 29 , 45 , 52 ). Antennae long, slender and only slightly clavate ( Figs 20, 21 , 28, 29 , 37 , 45 , 51, 52 ), extending until metatergum 3 (♂) or slightly past metatergum 2 (♀) when stretched dorsally. In length, antennomere 3>2=4=5=6>>1=7. Interantennal isthmus ca 1.5x as wide as diameter of antennal socket ( Figs 45 , 52 ). Tegument shining, mostly smooth, in places fainty rugulose dorsally (especially so on rear halves of metaterga), roughly ribbed at bottom of strictures between pro- and metazonae, less strongly beaded at bottom of transverse metatergal sulci, roughly granulate on sides below paraterga ( Figs 28 , 37 , 51 ). In width, head> collum> rings 6–15> 2 = 5> 3=4; body gradually tapering on rings 16–20 ( Fig. 20 ). Paraterga small, especially poorly developed in ♀ compared to ♂, mostly lying at about upper 1/3 body, narrowly bordered, slightly and regularly rounded laterally, especially so on collum ( Figs 20, 21 , 28–31 , 37–39 , 45–47 , 51–54 ), poreless paraterga slightly thinner than pore-bearing ones, calluses smooth, slightly sinuate dorsally only before ozopores, delimited by distinct sulci both dorsally and ventrally; caudal corners of postcollum paraterga narrowly rounded to nearly pointed, at most barely to slightly produced past rear tergal margin ( Figs 20, 21 , 28–31 , 37–39 , 45–47 , 51–54 ). Paraterga 2 especiallly low, acutangular and slightly drawn only anteriad, but obtuse, rounded and not produced caudad. Ozopores fully lateral, invisible from above, lying at bottom of narrow oblong grooves. Tergal setae fully abraded, setation pattern vague, but partly traceable as insertion points. Limbus entire. Transverse metatergal sulci clear-cut on rings 5–17, less distinct on ring 18, missing on 19 th. Axial line absent, but occasionally poorly traceable on rear halves of metaterga. Pleurosternal carinae low, largely bimodal and roughly granulated ridges visible on rings 2–7, thereafter retained as barely discernible and increasingly reduced swellings (♂, ♀). Epiproct ( Figs 20, 21 , 31 , 39 , 47 , 54 ) long, tip barely concave, lateral pre-apical papillae very small. Hypoproct ( Fig. 21 ) roundly tapeziform, caudal margin with 1+1 setae borne on very distinct and round knobs.

Sterna very densely hirsute, cross-impressions weak, devoid of modifications other than sternal lobe between legs 4 being high, spatuliform, roundly subtriangular to subtrapeziform, densely setose on both sides ( Figs 21 , v; 37 ). Legs long, 1.5–1.7x (♂) or 1.2–1.3x (♀) as long as body height (♂), very densely setose, especially so ventrally, true tibial and tarsal brushes present on all ♂ legs but two last legpairs ( Figs 21 , 29 , 37 ); adenostyles round, setose, parabasal tubercles present ventrally on ♂ femora 1 ( Fig. 21 , a). In length, femur> tarsus> coxa = prefemur = postfemur = tibia ( Fig. 37 ).

Gonopods ( Figs 22–27 , 32–36 , 40–44 , 48–50 , 55–57 ) complex, in situ both crossing each other only distomesally. Coxite short, subcylindrical, sparsely setose on ventral side; cannula as usual, a short and strongly curved hollow tube. Prefemoral (= densely setose) part about one-third as long as femorite, usually with a small, but evident lateral parabasal bulge ( Fig. 32 , p), set off from a very long, slender, erect, sagittally flattened and basically untwisted femorite by a distinct cingulum basally and a similarly distinct, but oblique cingulum apically, a small to only slightly larger, lateral, rounded lobule (o) marking both the apical cingulum and a very long, mesal, slender, straight distofemoral, spiniform process (b); seminal groove running entirely on mesal side of femorite to move onto a long, free, subflagelliform solenomere (sl) near base of b; postfemoral part (= solenophore, sph) strongly elongate, but only a little longer than femorite, more or less clearly curved to coiled, directed mesad, divided at base into a strong, prominent, membranous, lateral, shorter subtriangular and apically pointed to longer subpyriform and rounded lobe (lo) and a slender, ribbon-shaped, main sph branch supporting and concealing sl inside a groove, the latter showing a delicately membranous end.

REMARKS. Delarthrum Attems, 1936 , as well as the entire tribe Polydrepanini Jeekel, 1968 this genus belongs to, have recently been reviewed [ Golovatch et al., 2021]. The tribe has been shown to comprise seven genera, mostly small and confined to southern India, among which Delarthrum appears to be especially diverse (55 species, largely Himalayan) and widespread (ranging from the Western Ghats in the south to the Himalayas of Pakistan, Nepal, China / Tibet, and India in the north).

Based on the slender, long and untwisted gonopodal femorite, the flagelliform to somewhat ribbon-shaped solenomere basally devoid both of a loop/curve and a protecting lobe, as well as a complex, varied and large solenophore often obliquely truncate ventrad or dorsad, all this being characteristic of Delarthrum [ Golovatch et al., 2021], D. telnovi sp.n. definitely belongs to the very large group of Himalayan species that formerly composed the genus Orophosoma Jeekel, 1980 [ Golovatch, 1996], but is presently distinguished as the hingstoni -group [ Golovatch et al., 2021]. The gonofemorite is long and slender, untwisted, truncate apicoventrad, bearing a long, spiniform, ventral, distofemoral process (b) at the base of a long and subflagelliform solenomere (sl), the latter starting opposite an evident, rounded, apicodorsal lobe (o) that marks a distinct postfemoral cingulum. However, the solenophore (sph) in D. telnovi sp.n. is hypertrophied, unusually long and slender, directed and fully to nearly fully coiled mesad, bearing a conspicuous, large, lateral, membranous lobe (lo) near the sph base.

As regards morphological structures, both peripheral and gonopodal, Delarthrum telnovi sp.n. shows unexpectedly considerable variations in body size and in certain minor details of gonopodal conformation. This is to be plotted against the background of a relatively vast geographic distribution that covers parts of as many as three administrative districts (Humla, Mugu and Jumla, all in Karnali Province) in western Nepal, coupled with an unusually wide range of elevations (1655–3880 m a.s.l.). Despite all this, based on the quite uniform and generally stable peripheral and gonopodal structures that seem to reflect individual or populational variations at most, I do not hesitate to formally consider Delarthrum telnovi sp.n. as a single, albeit rather polymorphous and widespread species. Figures 20–57 are meant to reinforce this conclusion, although it basically contradicts the general assumption that most of the Himalayan Diplopoda (>270 species) are very narrowly endemic and restricted to very small areas, including altitudinal belts [ Golovatch, Martens, 2018]. This holds true for the numerous (53) Himalayan Delarthrum spp. as well, which appear to range from 600 to 4100 m in elevation, but are largely mid- to highmontane (1400–3000 m a.s.l.) [ Golovatch, Martens, 2018].

Figures

Figs 20, 21. Habitus of Delarthrum telnovi sp.n., # holotype, dorsal and ventral views, respectively. Designations: a — adenostyle on femur 1; v — ventral sternal lobe between coxae 4. Photographs by K.V. Makarov, taken not to scale. Рис. 20, 21. ОбЩий вид Delarthrum telnovi sp.n., голотип #, соответственно сверху и сниЗу. ОбоЗначениЯ: a — аденостиль на бедре 1; v — нижнЯЯ стернальнаЯ пластинка между таЗиками 4. Фотографии К.В. Макарова, снЯто беЗ масШтаба.

Figs 22–27. Right gonopod of Delarthrum telnovi sp.n., # holotype, dorsomesal, mesal, ventromesal, subdorsal, dorsolateral and lateral views, respectively. Designations: b — long and straight femoral process; lo — laterobasal lobe of solenophore; o — small lateral lobule marking an apicofemoral cingulum; sl — solenomere; sph — solenophore. Photographs by K.V. Makarov, taken not to scale. Рис. 22–27. Правый гонопод Delarthrum telnovi sp.n., голотип #, соответственно одновременно сверху и иЗнутри, иЗнутри, одновременно сниЗу и иЗнутри, почти сверху, одновременно сверху и сбоку, а также сбоку. ОбоЗначениЯ: b — длинный и прЯмой отросток бедра; lo — боковаЯ пластина у основаниЯ соленофора; o — маленькаЯ боковаЯ пластинка, отмечаюЩаЯ кольцо на верШине бедра; sl — соленомер; sph — соленофор. Фотографии К.В. Макарова, снЯто беЗ масШтаба.

Figs 28–36. Delarthrum telnovi sp.n., # paratype from 12–13 km SE of Simikot. 28 — habitus, lateral view; 29 — anterior part of body, ventral view; 30, 31 — midbody rings and posterior part of body, respectively, dorsal view; 32–36 — left gonopod, lateral, dorsolateral, dorsomesal, mesal and subventral views, respectively. Designation: p — lateral parabasal bulge on prefemorite. Photographs by K.V. Makarov, taken not to scale. Рис. 28–36. Delarthrum telnovi sp.n., паратип # иЗ 12–13 км ЮВ Simikot. 28 — обЩий вид, сбоку; 29 — переднЯЯ часть тела, сниЗу; 30, 31 — соответственно среднетуловиЩные сегменты и ЗаднЯЯ часть тела, сверху; 32–36 — левый гонопод, соответственно сбоку, одновременно сверху и сбоку, одновременно сверху и иЗнутри, иЗнутри и почти сниЗу. ОбоЗначение: p — боковое блиЗкое к основанию предбедра вЗдутие. Фотографии К.В. Макарова, снЯто беЗ масШтаба.

Figs 37–44. Delarthrum telnovi sp.n., # paratype from 12–13 km SE of Simikot. 37 — habitus, lateral view; 38, 39 — midbody rings and posterior part of body, respectively, dorsal view; 40–44 — right gonopod, lateral, sublateral, dorsolateral, subventral and mesal views, respectively. Designation: p — lateral parabasal bulge on prefemorite. Photographs by K.V. Makarov, taken not to scale. Рис. 37–44. Delarthrum telnovi sp.n., паратип # иЗ 12–13 км ЮВ Simikot. 37 — обЩий вид, сбоку; 38, 39 — соответственно среднетуловиЩные сегменты и ЗаднЯЯ часть тела, сверху; 40–44 — правый гонопод, соответственно сбоку, почти сбоку, одновременно сверху и сбоку, почти сниЗу и иЗнутри. ОбоЗначение: p — боковое блиЗкое к основанию предбедра вЗдутие. Фотографии К.В. Макарова, снЯто беЗ масШтаба.

Figs 45–50. Delarthrum telnovi sp.n., # paratype from 34.5 km SE — 41 km E of Simikot. 45 — anterior part of body, ventral view; 46, 47 — midbody rings and posterior part of body, respectively, dorsal view; 48–50 — right gonopod, mesal, ventral and lateral views, respectively. Photographs by K.V. Makarov, taken not to scale. Рис. 45–50. Delarthrum telnovi sp.n., паратип # иЗ 34,5 км ЮВ — 41 км В Simikot. 45 — переднЯЯ часть тела, сниЗу; 46, 47 — соответственно среднетуловиЩные сегменты и ЗаднЯЯ часть тела, сверху; 48–50 — правый гонопод, соответственно иЗнутри, сниЗу и сбоку. Фотографии К.В. Макарова, снЯто беЗ масШтаба.

Figs 51–54. Delarthrum telnovi sp.n., # paratype from Rara National Park. 51 — habitus, lateral view; 52 — anterior part of body, anterior view; 53, 54 — midbody rings and posterior part of body, respectively, dorsal view. Photographs by K.V. Makarov, taken not to scale. Рис. 51–54. Delarthrum telnovi sp.n., паратип # иЗ национального парка Rara. 51 — обЩий вид, сбоку; 52 — переднЯЯ часть тела, спереди; 53, 54 — соответственно среднетуловиЩные сегменты и ЗаднЯЯ часть тела, сверху. Фотографии К.В. Макарова, снЯто беЗ масШтаба.

Figs 55–57. Right gonopod of Delarthrum telnovi sp.n., # paratype from Rara National Park, mesal, subventral and sublateral views, respectively. Photographs by K.V. Makarov, taken not to scale. Рис. 55–57. Правый гонопод Delarthrum telnovi sp.n., паратип # иЗ национального парка Rara, соответственно иЗнутри, почти сниЗу и почти сбоку. Фотографии К.В. Макарова, снЯто беЗ масШтаба.

Figs 58–60. Pictures of the type localities of Chondromorpha greke sp.n. (58) and Delarthrum telnovi sp.n. (59: 13.5–13.9 km SE of Simikot, and 60: 34.5 km SE — 41 km E of Simikot), all courtesy D. Telnov (Riga, Latvia). Рис. 58–60. Фотографии типовых местностей Chondromorpha greke sp.n. (58) и Delarthrum telnovi sp.n. (59: 13,5–13,9 км ЮВ Simikot, и 60: 34,5 км ЮВ — 41 км В Simikot), все любеЗно предоставлены Д. Тельновым (Рига, ЛатвиЯ).