Omodeoscolex abamaensis Bartz & Decaëns, 2024

Decaëns, Thibaud, Bartz, Marie Luise Carolina, Bartz, arolina, Feijoo-Martínez, Alexander, Goulpeau, Arnaud, Lapied, Emmanuel, Marchán, Daniel F., Maggia, Marie-Eugénie, Papuga, Guillaume & James, Samuel W., 2024, Earthworms (Oligochaeta, Clitellata) of the Mitaraka range (French Guiana): commented checklist with description of one genus and eighteen species new to science, Zoosystema 46 (9), pp. 196-244 : 231-233

Omodeoscolex abamaensis Bartz & Decaëns , n. sp.

( Fig. 20 )

urn:lsid:zoobank.org:act:1FE90ABA-30AB-4AC1-AE8D-35CBD888435C

TYPE MATERIAL. — Holotype. French Guiana • Adult; Tumuc-Humac, Mitaraka Massif , lowland forest on DIADEMA project A trail, in decaying trunk; 2°14’34”N, 54°27’54”W; 327 m a.s.l.; III.2015; T. Decaëns, E. Lapied leg.; BOLD Sample ID: EW-MI15-0248 ; MNHN.

Paratypes. French Guiana • 2 adult specimens; Tumuc-Humac, Mitaraka Massif , lowland forest on DIADEMA project A trail; 2°14’34”N, 54°27’54”W; 327 m a.s.l.; III.2015; T. Decaëns, E. Lapied leg.; BOLD Sample ID: EW-MI15-0247 , EW-MI15-0249 ; CEFE • 1 adult specimen; Tumuc-Humac, Mitaraka Massif , lowland forest on DIADEMA project D trail; 2°13’58”N, 54°27’7”W; 318 m a.s.l.; III.2015; T. Decaëns, E. Lapied leg.; BOLD Sample ID: EW-MI15-0305 ; MNHN • 1 adult specimen; 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-MI15-0299 ; MNHN .

OTHER MATERIAL EXAMINED. — French Guiana • 1 fragment; Tumuc-Humac, Mitaraka Massif , Heliconia forest near plateau forest at base camp; 2°13’50”N, 54°26’57”W; 351 m a.s.l.; III.2015; T. Decaëns, E. Lapied leg.; BOLD Sample ID: EW-MI15-0035 , MNHN • 1 juvenile specimen; Tumuc-Humac, Mitaraka Massif , lowland forest on DIADEMA project D trail; 2°13’58”N, 54°27’7”W; 318 m a.s.l.; III.2015; T. Decaëns, E. Lapied leg.; BOLD Sample ID: EW-MI15-0310 ; MNHN .

ETYMOLOGY. — The name of the species refers to the Abama River along which the expedition base camp was located.

ECOLOGY. — The three specimens of O. abamaensis Bartz & Decaëns , n. sp. were found in decaying trunks and termite nest in a lowland, a slope and a plateau forest ( Fig. 20C, D ).

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

DESCRIPTION

External morphology ( Fig. 20A, B )

Body shape cylindrical, slightly flattened posteriously. Body pigmentation dorsally light yellow-brown, ventrally lighter. Body length: 18 mm in the holotype, 14 to 21 mm in two of the paratypes, after ethanol fixation. Body mass: 0.03 g after ethanol fixation in the holotype, 0.02 to 0.03 g in two of the paratypes. Diameter: 1.4 to 1.5 mm in the preclitellar region, 1.0 to 1.6 mm in the clitellum, 1.0 to 1.6 mm in the postclitellar region. Number of segments: 109 in the holotype, 95 to 122 in two of the paratypes. Prostomium tanylobic. Dorsal pores begining in 4/5. Setae closely paired, beginning in II, ab ventral and cd sub-ventral. Setal arrangement aa:ab:bc:cd = 4:1:4:1, dd> ½ Ø. Clitellum in XIII-XX, annular. Genital markings in acanthodriline male field in XVII-XIX, delimited anteriously and posteriously by two transversal lips in 3/4XVII and 1/4XX, respectively. One pair of ventral male pores in XVIII, and ovipores one pair in XIV, presetal, internally diagonal to a. Spermathecal pores not visible. Nephridial pores not visible.

Internal anatomy

Septa: membranous. Gizzard: absent. Calciferous glands: two pairs in XIV and XV, with lamellar structure, kidney-shaped and attached through the middle inside. Esophagus-intestine transition in XVI. Typhlosole absent. Hearts: five pairs, last three intestinal bigger and last pair in XII. Excretory apparatus holoic. Prostatic glands: two pairs in XVII and XIX, short. Ovaries: one pair in XIII, small sacs containing ovules.Testes: two pairs of testes sacs in X and XI. Seminal vesicles: one pair in XII, small. Spermathecae: three unpaired midventral in VII to IX, spherical.

REMARKS Omodeoscolex abamaensis Bartz & Decaëns , n. sp. is close to O. touroulti Decaëns & Bartz , n. sp. in presence of three unpaired spermathecae ( Table 5 ). It however differs from this species by its DNA barcode (mean pairwise divergence> 16% with these species; Table 3 ), and by the position of spermathecae (i.e., in VII to IX instead of VI to VIII in O. touroulti Decaëns & Bartz , n. sp.). This species corresponds to OTU#072 in Maggia et al. (2021).

Figures

FIG. 20. — Omodeoscolex abamaensis Bartz & Decaëns n. sp.: A, external and lateral view of the anterior body (arrows indicate the clitellum position); B, external and ventral view of the anterior body (arrows indicate the clitellum male field); C, habitat preferences; D, microhabitat preferences. All images from the holotype; CL, clitellum; MF, male field; N, total number of specimens in the dataset. Scale bars: 1 mm.