Australobius chagosensis Popovici & Edgecombe, 2024
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publication ID |
https://doi.org/ 10.1080/00222933.2024.2395903 |
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DOI |
https://doi.org/10.5281/zenodo.14240606 |
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persistent identifier |
https://treatment.plazi.org/id/BE5787BE-AB0D-0454-FE82-FCEF65F87AFD |
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treatment provided by |
Plazi |
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scientific name |
Australobius chagosensis Popovici & Edgecombe |
| status |
sp. nov. |
Australobius chagosensis Popovici & Edgecombe sp. n.
( Figures 1 View Figure 1 , 2 View Figure 2 (A–l))
urn:lsid:zoobank.org:act:4FC7008A-F1DD-4D39-8831-E642AB062676
Etymology
The specific epithet reflects the origin of the two known specimens, both from Diego Garcia in the Chagos Archipelago.
Type material
Holotype, NHMUK015619673 About NHMUK , ♀, Diego Garcia, 7.359°S, 72.432°E, leaf litter, 02 July 2022, leg. W. Rabitsch. GoogleMaps Paratype NHMUK015626351 About NHMUK , juvenile ♀, Point Marianne Culture site, 7.319°S, 72.427°E, leaf litter, 22 June 2022, leg GoogleMaps . W GoogleMaps . Rabitsch.
Diagnosis
Small-sized Australobius , body length 7–10 mm. Antenna with 19–20 articles. 4 + 4 ocelli of similar size. Anterior margin of forcipular coxosternite with 3 + 3 teeth; small spiniform porodont situated between the medial and outermost teeth. Tergites 9, 11 and 13 with small posterior triangular projections. Ultimate leg pair with greatly reduced tarsus 2, less than 1/3 length of tarsus 1; ultimate leg apical claw simple. Female gonopods with 3 + 3 slender spurs and a trifurcate claw.
Description
Habitus. Body length 10 mm (holotype), 7 mm (paratype). Colour in ethanol dark brown with violet pigmentation in the anterior part of the body and the proximal articles of the legs. Head and antennae. Cephalic plate of subequal length and width; frontal margin with medial notch ( Figure 1 View Figure 1 (A)). 4 + 4 ocelli, arranged in two rows comprising two ocelli each ( Figure 1 View Figure 1 (B,C)). Principal ocellus only slightly larger than seriate ocelli, all of which are of similar size. Tömösváry’s organ small, positioned below the principal ocellus ( Figure 1 View Figure 1 (B)). Antenna with 19 (holotype, one complete antenna)–20 articles; 2.4 times longer than the cephalic capsule and 25% of body length ( Figure 1 View Figure 1 (A)).
Forcipular segment. Anterior margin of forcipular coxosternite only slightly protruding, with 3 + 3 teeth of roughly equal size ( Figure 1 View Figure 1 (D)). Porodont slender, spiniform, situated between the medial and outermost teeth ( Figure 1 View Figure 1 (E,F)). Dental margin continuous with the remainder of the anterior margin. Median diastema broadly U-shaped (holotype: Figure 1 View Figure 1 (D)) or rounded V-shaped (paratype: Figure 1 View Figure 1 (E)).
Trunk. Large tergites wrinkled, with evident lateral but indistinct posterior margination. Posterior angles of tergites 9, 11 and 13 of holotype with small, feeble triangular projections ( Figure 1 View Figure 1 (G)) but these are completely absent in the paratype ( Figure 2 View Figure 2 (A)). Coxal pores on legs 12–15, round, arranged as 2, 3, 3, 3/2, 3, 3, 3 (paratype) or 3, 3, 4, 4/3, 4, 5, 4 (holotype) ( Figure 2 View Figure 2 (I)).
Ultimate leg-bearing and postpedal segments. Ultimate leg telopodite slender and elongate ( Figure 2 View Figure 2 (C)).Tarsus 2 greatly reduced in size,only 24.5% (paratype) – 31% (holotype) of the length of tarsus 1 ( Figure 2 View Figure 2 (C–F)). Telopodite of leg pair 14 similarly elongate but tarsus 2 not greatly reduced in size ( Figure 2 View Figure 2 (B,G)). Pretarsus without accessory claws, main claw bearing a minute anteroventral spine ( Figure 2 View Figure 2 (H)). Female gonopods with 3 + 3 elongate, slender spurs ( Figure 2 View Figure 2 (J,K)); apical claw with well-developed lateral and medial denticles ( Figure 2 View Figure 2 (I)). Gonopods of immature female paratype with 2 + 2 minute spurs ( Figure 2 View Figure 2 (L)). Male unknown.
Plectrotaxy. As in the following tables (C, coxa; P, prefemur; T, tibia; t, trochanter; a. anterior; m, median; p. posterior).
Plectrotaxy of female holotype ( NHMUK015619673 About NHMUK ) .
Discussion. The specimens from Diego Garcia compare most closely to A. sculpturatus ( Pocock, 1901) (revised by Eason 1973), from southern India, Sri Lanka, the Laccadives and the Maldives, and A. palnis ( Eason, 1973) from Sri Lanka ( Eason 1993). Similarities include the low number of ocelli, no more than diminutive posterior projections on tergites 9, 11 and 13, slender spurs on the female gonopods, and plectotraxy. However, examination of the types of both A. sculpturatus and A. palnis , as well as specimens from the Maldives assigned to the former, shows a substantially longer tarsus 2 than in both specimens of A. chagosensis ( Figure 2 View Figure 2 (M,N) vs Figure 2 View Figure 2 (C)). Additional characters in which A. chagosensis differs include ocelli more homogeneous in size, and 3 + 3 (vs 4 + 4 or 3 + 4) teeth on the anterior margin of the forcipular coxosternite.
The position of the porodont, between the second and third teeth, is shared with Australobius malayicus ( Verhoeff, 1937) ; however, A. chagosensis can be distinguished from that Malaysian species by the fewer ocelli (four vs six) and 3 + 3 vs 4 + 4 coxosternal teeth.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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