Georgiosoma bicornutum

Antić, Dragan Ž. & Makarov, Slobodan E., 2016, The Caucasus as a major hotspot of biodiversity: Evidence from the millipede family Anthroleucosomatidae (Diplopoda, Chordeumatida), Zootaxa 4211 (1), pp. 1-205 : 68-71

Georgiosoma bicornutum gen. et sp. nov.

Figs 53–55

Diagnosis. As for the genus.

Etymology. An adjective; the new species is named after a pair of horns on the anterior gonopods.

Material studied (total: 2 males, 1 juvenile). Holotype. GEORGIA: male, Cave " Grot Lagernaya 1" near Okureshi, 2000 m, 21 Sep.–14 Oct. 1983, A. Tirakh & V.Y. Dolzhanskiy leg. ( ZMUM ρ3229).

Paratypes (total: 1 male, 1 juveniles). Both from GEORGIA: 1 male, 1 juvenile, same data as holotype ( ZMUM ρ3230).

Type locality. GEORGIA: Cave " Grot Lagernaya 1" near Okureshi.

Description. Body with 30 segments (including telson) in adults.

MEASUREMENTS. Males 20 mm long, vertical diameter of the largest pleurotergite 1.5 mm.

COLORATION ( Fig. 53 ). Yellowish white.

HEAD. Slightly concave in males. Labrum with three medial teeth and 4+4 labral and 2+2 supralabral setae. Promentum triangular, without setae. Lingual plates with 10+12 setae, on each plate arranged in 3 irregular rows. Stipites with ca 40+40 setae. Antennae elongated, 3.4 mm long in holotype. Length of antennomeres (in mm): I (0.13), II (0.25), III (1), IV (0.54), V (0.98), VI (0.26), VII (0.22) and VIII (0.02). Length/breadth ratios of antennomeres I–VII: I (1), II (1.3), III (6.7), IV (3.4), V (6), VI (1.6) and VII (2). Antennomeres II, IV, V, VI and VII with one, three, one, four and one sensillum, respectively. Number of ocelli 6, arranged in 3 rows in males.

COLLUM. Narrower than head, with six macrochaetae. Anterior edge semi-circular, posterior margin gently concave.

BODY SEGMENTS ( Fig. 53 ). Lateral keels well-developed. Macrochaetae medium-sized, outer longer than medial and inner, all trichoid. CIX (pleurotergite 15) ~ 0.75; MIX (pleurotergite 15) ~ 1.5; PIX (pleurotergite 15) ~ 0.6; MA (pleurotergite 15) ~ 135˚.

TELSON. Epiproct with a pair of spinnerets and 3+3 setae (1+1 paramedian, 2+2 marginal). Hypoproct with 1+1 apical setae. Paraprocts with 3+3 marginal setae.

WALKING LEGS ( Fig. 53 ). Leg-pairs 1 and 2 with tarsal combs; prefemora with several long and robust setae; femora and postfemora with a group of several long and robust setae.

MALE SEXUAL CHARACTERS ( Fig. 54 ). Leg-pairs 3–7 enlarged. Leg-pairs 3 and 4 each with a basal external protrusion on prefemur. Leg-pair 5 with a strongly developed protrusion on prefemur. Leg-pair 6 without peculiarities. Coxae of leg-pair 7 with a well-developed, mesally curved horn, anteriorly with a subtriangular protrusion. Leg-pair 10 with coxal glands and well-developed coxal horns. Leg-pair 11 with coxal glands and short posterior coxal processes.

ANTERIOR GONOPODS ( Fig. 55 A–C). Sternal plate ( sp) anteriorly with a medial, triangular, acuminate, hairy, sternal sac ( ss). Coxal processes ( cp) fused, only distally with a notch ( n) and an anterior longitudinal groove ( lg), forming a rounded shield with two well-developed, subtriangular and acuminate horns ( sah) in anterior and posterior views. These horns connected to posterior lamellae ( pl) supporting denticles and setae in upper half. Mediodistal parts ( mp) with denticulate upper edges and mesal edges folded inside and forming a denticulate winglike structure. Posteriorly, two diagonal rows of setae ( rs) present.

POSTERIOR GONOPODS ( Fig. 55 D). Coxites ( c) divided. Telopodites ( t) present on posterolateral side, clothed with setae. Coxal processes ( cp) horn-like, clothed with minute setae. Coxal vesicles ( cv) present on anterior side.

Notes. This species is only known from a cave and shows some troglomorphic features such as reduced body pigmentation and number of ocelli, a larger number of setae on the gnathochilarium, as well as elongated antennae and walking legs.

Figures

FIGURE 53. Georgiosoma bicornutum gen. et sp. nov., holotype male habitus. Scale line = 1 mm.

FIGURE 54. Georgiosoma bicornutum gen. et sp. nov., paratype male. A. Leg 3. B. Leg 10. C. Leg 4. D. Leg 7. E. Leg 11. Scale lines = 0.2 mm.

FIGURE 55. Georgiosoma bicornutum gen. et sp. nov., paratype male gonopods. A. Anterior gonopods, anterior view. B. Anterior gonopods, lateral view. C. Anterior gonopods, posterior view. D. Posterior gonopods, posterior view. c = coxite; n = distal notch; t = telopodite; cp = coxal process; cv = coxal vesicle; lg = logitudinal groove; mp = medial part; pl = posterior lamella, rs = row of setae; sp = sternal plate; ss = sternal sac; sah = subtriangular, acuminate horns. Scale line = 0.3 mm.