Enghoffosoma extraspinosum, Gordana & Ambros, 2018

Golovatch, S. I. & Semenyuk, I. I., 2018, On several new or poorly-known Oriental Paradoxosomatidae (Diplopoda: Polydesmida), Arthropoda Selecta 27 (1), pp. 1-21 : 6-7

Enghoffosoma extraspinosum sp.n.

Figs 4 , 14–31 .

HOLOTYPE ♂, Vietnam, Gia Lai Prov., Kon Ka Kinh National Park , N 14°12′43″, E 108°18′57″, 900 m a.s.l., mixed wet tropical forest at bottom of a river valley, on log, V.2017, leg. I.I. Semenyuk.

PARATYPES: 3 ♂♂, 1 ♀, same data, together with holotype.

DIAGNOSIS. Differs from other Enghoffosoma spp. primarily in the presence of an additional process (a) on the gonopod.

NAME. To emphasize the presence of an additional process (a) on the gonopod; adjective.

DESCRIPTION. Holotype and ♂ paratypes ca 21–22 mm long, width of midbody pro- and metazonae 2.6 and 3.0 mm, respectively. ♀ paratype ca 25 mm long, 3.0 and 3.4 mm wide on pro- and metazonae, respectively. General coloration in alcohol rather uniformly dark brown to brown, apparently somewhat faded, with a characteristic pattern of contrasting light creamy rear halves of paraterga and entire venter, legs light brown, tips of antennae pallid ( Figs 22– 25 ). Live coloration darker, but pattern clear, blackish orange ( Fig. 4 ).

Clypeolabral region densely setose, abundant small and a few longer setae between and above antennae, respectively; occipital region bare; epicranial suture thin, superficial ( Fig. 14 ). Antennae long and slender, only slightly clavate ( Figs 22, 23 ), in situ extending back behind segment 2 (♂) when stretched dorsally; in length, antennomeres 2–6 >> 1 = 7 ( Fig. 22 ); interantennal isthmus about 1.1 times as broad as diameter of antennal socket ( Fig. 22 ).

In width, head <segment 2 = 3 <collum = 4 <5–16; thereafter body gradually tapering towards telson ( Figs 22– 25 ). Tegument nearly shining, almost dull; prozonae very finely shagreened; metaterga mostly smooth, longitudinally striolate in rear halves; surface below paraterga granulate and clearly striate longitudinally. Collum broadly rounded laterally, with small, subhorizontal, rounded, caudally subrectangular paraterga. Postcollum paraterga well-developed, mostly set low at about half of body height, oblique and clearly elevated caudally; caudal corner of paraterga 2 narrowly rounded, thereafter sharp, beak- or spine-shaped and drawn behind rear tergal margin ( Figs 22, 24, 25 ), only paraterga 18 and 19 increasingly small ( Fig. 25 ). Calluses delimited by a distinct sulcus only dorsally, particularly thin on poreless paraterga, somewhat thicker and slightly sinuate only in front of ozopore on pre-bearing paraterga. Ozopores small, lying inside short dorsolateral grooves, partly visible from above, located at about 1/4 off caudal corner ( Figs 22, 24, 25 ). Transverse metatergal sulci absent, often with very faint impressions in their stead. Stricture between pro- and metazonae very thin and shallow, clearly beaded at bottom down to paraterga. Tergal setae largely abraded, short (about 1/4 of metatergal length, Fig. 24 ), setation pattern traceable as 2+ 2 in a transverse row in anterior 1/3 of metaterga. Axial line missing. Pleurosternal carinae small flaps on segment 2, square ridges on segment 3, thereafter with an increasingly distinct caudal tooth until segment 7 (♂), then increasingly reduced on segments 8–16, traceable like small denticles even on segments 17–19 (♂) ( Fig. 22 ) or 17–18 (♀). Epiproct rather long, coniform, subapical lateral papillae small, tip subtruncate ( Figs 22, 25 ). Hypoproct roundly subtriangular, 1+1 setae strongly separated from each other, borne on minute knobs, clearly removed from caudal margin.

Sterna very densely setose, cross-impressions faint, axial impression especially poor; a very small, sharp, vestigial tubercle or cone near each coxa (♂); a low, setose, roundly subtrapeziform lobe between ♂ coxae 4. Legs long and slender, very densely setose, somewhat incrassate as compared to ♀, ca 1.5–1.6 (♂) or 1.1 –1.2 (♀) times as long as midbody height, devoid of adenostyles, ♂ prefemora clearly bulged laterally, tarsal brushes present only on ♂ legs 1–7, thereafter thinning out; in length, femora >> tarsi> tibiae = prefemora> postfemora = coxae (♂).

Gonopods ( Figs 23 , 28–31 ) rather complex, in situ slightly crossing each other distomedially; coxite about as long as femorite, subcylindrical, densely setose distolaterally; prefemoral (= densely setose) part of telopodite short, about 1/3 as long as acropodite; femorite (fe) long, slender, untwisted, slightly enlarged apically only due to a short, but bulky postfemoral region (pf); the latter set off basally from fe by an inconspicuous sulcus (s) on mesal face and distally by a prominent apical shelf/cingulum (b); pf with a single, distinct, dorsomesal, spine-shaped process (p); base of a long, twisted, gradually attenuating solenomere (sl) with two subequal membranous outgrowths, one (e) axe-shaped and dorsomesal in position, the other (a) spatuliform and ventromesal in location.

REMARKS. At the moment, the rather large Oriental genus Enghoffosoma Golovatch, 1993 encompasses 12 species described from Myanmar, Indochina and southern China [ Likhitrakarn et al., 2014; Nguyen, Golovatch, 2016; Golovatch et al., 2016]. The vivid colour pattern in E. extraspinosum sp.n. strongly resembles that observed in E. bispinum Likhitrakarn, Golovatch et Panha, 2014 , from Thailand, E. contrastum Golovatch, VandenSpiegel et Semenyuk, 2016 and E. digitatum Nguyen et Golovatch, 2016 , both from Vietnam, E. lanceolatum Likhitrakarn, Golovatch et Panha, 2014 , from both Thailand and Vietnam, and E. anchoriforme Likhitrakarn, Golovatch et Panha, 2014 , from both Laos and Vietnam [ Likhitrakarn et al., 2014; Nguyen, Golovatch, 2016; Golovatch et al., 2016], but they all are quite distinct in several somatic and, especially, gonopodal traits. Among congeners, the new species shows yet the maximum number (4) of clear-cut distal outgrowths on the gonopod.

Figures

Figs 3–5. Live coloration of Piccola latiterga sp.n., ♀ paratype, Enghoffosoma extraspinosum sp.n., ♂ holotype, and Touranella moniliformis sp.n., ♂ holotype, respectively. Pictures by I. Semenyuk. Рис. 3–5. ПрижиЗненнаЯ окраска соответственно Piccola latiterga sp.n. (паратип ♀), Enghoffosoma extraspinosum sp.n. (голотип ♂) и Touranella moniliformis sp.n. (голотип ♂). Фотографии И. Семенюк.

Figs 14–17. Piccola latiterga sp.n., ♂ paratype, left gonopod, mesal, dorsal, ventral and lateral views, respectively. Pictures by K. Makarov, not taken to scale. Рис. 14–17. Piccola latiterga sp.n., паратип ♂, левый гонопод, соответственно иЗнутри, сверху, сниЗу и сбоку. Фотографии К. Макарова, снЯты беЗ масШтаба.

Figs 18–21. Piccola latiterga sp.n., ♂ paratype, left gonopod, mesal, lateral, ventral and dorsal views, respectively. Drawn not to scale by I. Semenyuk. Рис. 18–21. Piccola latiterga sp.n., паратип ♂, левый гонопод, соответственно иЗнутри, сбоку, сниЗу и сверху. Нарисовала беЗ масШтаба И. Семенюк.

Figs 22–25. Enghoffosoma extraspinosum sp.n., ♂ holotype. 22 — habitus, lateral view; 23 — anterior part of body, ventral view; 24 — midbody segments, dorsal view; 25 — caudal part of body, dorsal view. Pictures by K. Makarov, not taken to scale. Рис. 22–25. Enghoffosoma extraspinosum sp.n., голотип ♂. 22 — обЩий вид, сбоку; 23 — переднЯЯ часть тела, сниЗу; 24 — среднетуловиЩные сегменты, сверху; 25 — ЗаднЯЯ часть тела, сверху. Фотографии К. Макарова, снЯты беЗ масШтаба.

Figs 26–27. Enghoffosoma extraspinosum sp.n., ♂ holotype, right gonopod, mesal and lateral views, respectively. Scale bar: 0.5 mm. Designations explained in text. Del. S. Golovatch. Рис. 26–27. Enghoffosoma extraspinosum sp.n., голотип ♂, правый гонопод, соответственно иЗнутри и сбоку. МасШтаб: 0,5 мм. ОбоЗначениЯ обЪЯснены в тексте. Рисунки С. Головача.

Figs 28–31. Enghoffosoma extraspinosum sp.n., ♂ paratype, left gonopod, ventral, mesal, dorsal and oral views, respectively. Drawn not to scale by I. Semenyuk. Рис. 28–31. Enghoffosoma extraspinosum sp.n., паратип ♂, левый гонопод, соответственно сниЗу, иЗнутри, сверху и спереди. Нарисовала беЗ масШтаба И. Семенюк.