Urobenus guianomeridionalis Bartz & Decaëns, 2024

Urobenus guianomeridionalis Bartz & Decaëns , n. sp.

( Fig. 15 View FIG )

urn:lsid:zoobank.org:act:

TYPE MATERIAL. — Holotype. French Guiana • Adult; Tumuc-Humac, Mitaraka Massif , slope forest on DIADEMA project C trail, in decaying trunk; 2°14’5”N, 54°26’42”W; 377 m a.s.l.; III.2015; T. Decaëns, E. Lapied leg.; BOLD Sample ID: EW-MI15-0078 ; MNHN. GoogleMaps

Paratypes. French Guiana • 2 adult specimens; Tumuc-Humac, Mitaraka Massif , hilltop forest on Borne 1 Inselberg ; 2°12’35”N, 54°26’12”W; 600 m a.s.l.; III.2015; T. Decaëns, E. Lapied leg.; BOLD Sample ID: EW-MI15-0218 , EW-MI15-0219 ; CEFE GoogleMaps • 1 adult specimen; Tumuc-Humac, Mitaraka Massif , hilltop forest on Sommet en Cloche Inselberg ; 2°13’42”N, 54°28’2”W; 638 m a.s.l.; III.2015; T. Decaëns, E. Lapied leg.; BOLD Sample ID: EW-MI15-0106 ; CEFE GoogleMaps • 1 adult specimen; Tumuc-Humac, Mitaraka Massif , plateau forest on DIADEMA project A trail; 2°14’38”N, 54°27’32”W; 371 m a.s.l.; III.2015; T. Decaëns, E. Lapied leg.; BOLD Sample ID: EW-MI15-0084 ; MNHN GoogleMaps • 1 adult specimen; Tumuc-Humac, Mitaraka Massif , plateau forest on DIADEMA project D trail; 2°12’57”N, 54°27’25”W; 381 m a.s.l.; III.2015; T. Decaëns, E. Lapied leg.; BOLD Sample ID: EW-MI15-0019 ; MNHN GoogleMaps • 1 adult specimen; Tumuc-Humac, Mitaraka Massif , slope forest on DIADEMA project D trail; 2°13’40”N, 54°27’14”W; 339 m a.s.l.; III.2015; T. Decaëns, E. Lapied leg.; BOLD Sample ID: EW-MI15-0262 ; MNHN GoogleMaps .

OTHER MATERIAL EXAMINED. — French Guiana • 1 juvenile specimen; Tumuc-Humac, Mitaraka Massif , hilltop forest on Sommet en Cloche Inselberg ; 2°13’42”N, 54°28’2”W; 638 m a.s.l.; III.2015; T. Decaëns, E. Lapied leg.; BOLD Sample ID: EW-MI15-0107 ; MNHN GoogleMaps • 1 juvenile specimen; Tumuc-Humac, Mitaraka Massif , plateau forest on DIADEMA project A trail; 2°14’38”N, 54°27’32”W; 371 m a.s.l.; III.2015; T. Decaëns, E. Lapied leg.; BOLD Sample ID: EW-MI15-0087 ; MNHN GoogleMaps • 2 juvenile specimens; Tumuc-Humac, Mitaraka Massif , plateau forest on DIADEMA project C trail; 2°13’58”N, 54°26’38”W; 449 m a.s.l.; III.2015; T. Decaëns, E. Lapied leg.; BOLD Sample ID: EW-MI15-0301 , EW-MI15-0302 ; MNHN GoogleMaps • 2 juvenile specimens; Tumuc-Humac, Mitaraka Massif , transition forest # 1 Sommet en Cloche Inselberg ; 2°13’54”N, 54°27’39”W; 401 m a.s.l.; III.2015; T. Decaëns, E. Lapied leg.; BOLD Sample ID: EW-MI15-0342 , EW-MI15-0343 ; MNHN GoogleMaps .

ETYMOLOGY. — This species is named in reference to the type locality situated in the south of French Guiana.

ECOLOGY. — Urobenus guianomeridionalis Bartz & Decaëns , n. sp. has been found in plateau forests (38.46% of specimens), in inselberg hilltop and transition forests (46.15% of specimens), and in slope forests (15.38% of specimens) ( Fig. 15D View FIG ). It is a specialist of epigeic microhabitats such as decaying trunks and litter accumulations on granite rocks ( Fig. 15G View FIG ).

DISTRIBUTION. — Urobenus guianomeridionalis Bartz & Decaëns , n. sp. is only known from the Mitaraka Massif.

DESCRIPTION

External morphology ( Fig. 15A, B View FIG )

Body shape cylindrical. Body pigmentation dorsally dark grey, ventrally beige to yellow. Body length: 35 mm in the holotype, 35 to 41 mm in the paratypes (average: 37.1 mm; n = 3), after ethanol fixation. Body mass: 0.11 g after ethanol fixation in the holotype, 0.10 to 0.14 g in the paratypes (average: 0.11 g; n = 3). Diameter: 1.2 to 2.8 mm in the preclitellar region, 3.4 to 4 mm in the clitellum, 2.7 to 3 mm in the postclitellar region. Number of segments: 87 in the holotype, 96 to 113 in the paratypes (average: 98.7; n = 3). Prostomium proepilobic. One pair of longitudinal grooves through segments I-II in line of nephridial pores. Setae closely paired, ab beginning in II and cd in III. Setal arrangement aa:ab:bc:cd:dd = 3:1:4:1:13. Clitellum in XV-XXIV, saddle-shaped ( Fig. 15A View FIG ). Genital markings absent. Tubercula pubertatis linear in 1/4XIX (½XIX)-XXIII ( Fig. 15B View FIG ). Male pores not recognised externally, internally open in 19/20, and ovipores in XIV, almost in the border of 13/14, in diagonal to b. Spermathecal pores in 6/7, 7/8 and 8/9. Nephridial pores begining in II.

Internal anatomy ( Fig. 15C View FIG )

Septa: membranous. Gizzard: muscular and well developed in VI, with an average size (width × length) of 1.87 × 2.07 mm. Calciferous glands: three pairs in VII-IX, of tubular paniculated structure and bean-shaped without appendix in VII-VIII, and sacs/trabecular and slightly curved oval shape in IX. Esophagus-intestine transition in XVII; intestine without caeca.Typhlosole abruptly begining in XXIII/XXV, laminar, long-folded lamella, occupying all the lumen. Hearts: two pairs of large intestinal hearts in X-XI, enclosed in the testes sacs. Excretory apparatus holoic. Testes sacs: in X and XI. Seminal vesicles: two pairs in XI-XII, small and lobulated, occupying only one segment; the pair in XI enclosed in septum and testes sac and the pair in XII free and slightly larger. Spermathecae: three pairs in VII to IX, small elongated without diverticula.

REMARKS

Urobenus guianomeridionalis Bartz & Decaëns , n. sp. is close to Urobenus brevis ( Omodeo, 1955) and U. brasiliensis in the position of the clitellum in XV-XXIV ( Benham 1886; Omodeo 1955). It differs mainly from the two species in its much smaller size ( 35 to 41 mm in length and 1.2 to 2.8 mm in anterior diameter, compared to 90 mm and 8 mm in U. brevis , respectively), the setal ratio (3:1:4:1:13, compared to 9:1:10:1: 38 in U. brevis ) and spermathecae lacking seminal chambers in U. guianomeridionalis Bartz & Decaëns , n. sp. ( Righi 1985). This species corresponds to OTU#052 in Maggia et al. (2021).