Dibolostethus inopinatus Means, Bouzan & Ivanov, 2023

Means, Jackson C., Bouzan, Rodrigo S., Iniesta, Luiz Felipe Moretti, Martínez-Torres, Daniela, Vasquez-Valverde, Luisa F., Brescovit, Antonio D. & Ivanov, Kaloyan, 2023, A review of the previously monotypic tribe Dibolostethini (Chelodesmidae: Chelodesminae) with description of two new species and a summary of the Chelodesmidae of the Tropical Andes Biodiversity Hotspot, European Journal of Taxonomy 885 (1), pp. 65-85 : 74-76

Dibolostethus inopinatus Means, Bouzan & Ivanov sp. nov.

urn:lsid:zoobank.org:act:8C1D05D6-D758-4825-9BDF-69E642BA219D

Figs 4C–D , 6 , 9

D. sicarius (in part) – Hoffman 2009: 151, misidentification.

Diagnosis

Adult males of D. inopinatus sp. nov. differ from those of D. kattani sp. nov. based on the lack of short, blunt projections on the sternite of the 5 th body ring, and from D. sicarius and D. kattani based on the following combination of gonopodal characteristics: solenomere sinuous before curving dorsally at nearly 90° at apex, outer edge with wide lateral flange just before apex, tip curving laterally ( Fig. 6A, C ); prefemoral process only slightly narrower than solenomere at base, with pronounced 45° angle on dorsal side, expanding at midpoint with lateral and medial edges becoming pronounced ridges widening into lamellate flanges on either side of prefemoral process; apex of prefemoral process acute, directed anteriad ( Fig. 6B ).

Etymology

The species epithet ‘ inopinatus ’ is Latin for ‘unexpected’, ‘unforeseen’, reflecting its surprising discovery among the type series of D. sicarius . The species epithet is a masculine, singular adjective.

Type material

Holotype ECUADOR • ♂; Cordillera del Cóndor, Morona-Santiago Province, Los Tayos [vicinity of Cueva de Los Tayos ]; 3°04′ S, 78°15′ W [originally reported incorrectly in decimal degrees]; 22 Jul. 1976; collector unknown; on log; VMNH110813 .

Description

Male (holotype, VMNH110813)

With characteristics typical for the genus. Coloration (preserved in 70% isopropanol): body rings, all appendages, and telson uniformly light yellow. Head: epicranial macrosetae 2–2, interantennal macrosetae 1–1, frontal macrosetae 2–2. Sternites: 4 th body ring with two slender, conical, acute projections, appressed along entire length ( Fig. 4C, D ). Gonopod aperture on 7 th body ring oval, rim notably projecting above sternite (0.48 mm), with a deep U-shaped concavity (0.2 mm) on posterior margin.

GONOPODS ( Fig. 6 ). Gonocoxae rounded, equivalent to about three quarters the length of the telopodite; with two macrosetae on the dorsum. Cannula appearing larger than in D. sicarius . Solenomere long, sinuous, unbranched, apex falciform and tip curving laterally ( Fig. 6 , S). Prefemoral process: long (similar in length to solenomere), narrow at base (width subequal to solenomere), widening at halfway point with lateral and medial flanges resembling a hooded cobra in lateral and medial views ( Fig. 6A, C ); medial flange with acute projection directed ventrally; prefemoral process and solenomere together resembling blacksmithing bolt tongs in lateral and medial views ( Fig. 6A, C ).

BODY MEASUREMENTS (mm). Total length 29.7, width of 10 th segment 1.95. Antennomere lengths (1–7): 0.48, 1.1, 1.1, 1.0, 1.05, 1.01, 0.28. Collum: length 0.8, width 1.55. Podomere lengths of 10 th body ring (1–7): 0.33, 0.55, 1.0, 0.55, 0.65, 1.01, 0.11. Gonopod aperture: length 0.50, width 0.75. Gonopod: length 0.93, width 0.71. Gonocoxae: length 0.7, width 0.38. Telopodite: length 0.89, width 0.35. Telson length 0.95.

Female

Unknown.

Distribution

Known only from the Morona-Santiago Province, Ecuador ( Fig. 9 ).

Remarks

Although no collector information is given on the specimen labels, review of material housed at VMNH revealed that D. inopinatus was collected during the “Los Tayos Expedition ”. The joint British-Ecuadorian expedition, which included over 100 researchers and supporting personnel, focused on exploring the archeology, geology, and biology of Cueva de Los Tayos , situated in the foothills of the Cordillera del Cóndor mountain range, and its vicinity between July 4 th and August 5 th, 1976.

Figures

Fig. 4. Body ring 4, sternal projections. A–B. Dibolostethus sicarius Hoffman, 2009, holotype, ♂ (VMNH110810). C–D. D. inopinatus Means, Bouzan & Ivanov sp. nov., holotype, ♂ (VMNH110813). A, C. Lateral views. B, D. Posterolateral views. Abbreviation: Cx = coxae.

Fig. 6. Dibolostethus inopinatus Means, Bouzan & Ivanov sp. nov., holotype, ♂ (VMNH110813), left gonopod. A. Lateral view, red circle = cingulum. B. Anterior view. C. Mesal view. Dashed lines = prostatic groove. Abbreviations: PfP = prefemoral process; S = solenomere.

Fig. 9. Distribution of Chelodesmidae spp. in the Tropical Andes Biodiversity Hotspot, by country. Note: the type locality of Dibolostethus sicarius Hoffman, 2009 is included for completeness although it falls just outside of the boundaries of the Tropical Andes Biodiversity Hotspot. For information on these taxa see Supp. file 1.