Leiogalathea sp.
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publication ID |
https://doi.org/ 10.1080/00222933.2023.2192429 |
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DOI |
https://doi.org/10.5281/zenodo.7975437 |
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persistent identifier |
https://treatment.plazi.org/id/03EF87E2-FFEF-FF91-FDF0-2AE3FC99FA9A |
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treatment provided by |
Plazi |
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scientific name |
Leiogalathea sp. |
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( Figures 2 View Figure 2 (g–h), 12)
Material examined
1 specimen of undetermined sex (2.9 mm PCL, 2.2 mm CW) (IO/SS/ANO/00126), Andaman Sea , off Middle Andaman Island, FORVSS stn 38619, 12.83°N, 93.06°E, 202 m depth, Naturalist̍s dredge, coll GoogleMaps . Vinay P GoogleMaps . Padate, 26 July 2019.
Description
Carapace. PCL 1.3 times width; dorsal surface bearing mostly medially interrupted transverse striae with dense short setae and lacking dorsal spines. Cervical grooves distinct. Lateral margins straight and subparallel, with 2 spines including 1 strong anterolateral and 1 small anterobranchial spine; posterior branchial region with 6 transverse ridges including posterior submarginal ridge. Intestinal region without transverse ridges. Frontal margins oblique. Rostrum triangular, 0.4 times half as long as PCL and 1.2 times as long as broad; lateral margins with 5 small teeth decreasing in size distally ( Figure 12 View Figure 12 (a)). Pterygostomian flap with long and short transverse ridges, anterior margin blunt ( Figure 12 View Figure 12 (b)).
Sternum. Thoracic sternite 3 width 4.4 times as wide as long, anterolaterally produced, anterior margin minutely serrated, with moderately deep median notch flanked by 2 distinct lobes. Sternites 4–7 smooth; sternite 4 2.4 times as wide as sternite 3, 2.5 times as wide as long, anterior margin widely contiguous to sternite 3 ( Figure 12 View Figure 12 (c)).
Pleon. Smooth; tergite 2 with 2 transverse ridges, tergites 3 and 4 each with 1 transverse ridge; tergite 5 smooth; tergite 6 and telson missing ( Figure 12 View Figure 12 (d)).
Eye. Ocular peduncle longer than wide; cornea subglobular; moderately large; cornea dilated, as wide as eyestalk ( Figure 12 View Figure 12 (e)).
Antennule and antenna. Missing.
Mxp 3. Ischium as long as merus; flexor margin terminating in sharp spine, extensor margin unarmed ( Figure 12 View Figure 12 (f)); crista dentata bearing 20 teeth ( Figure 12 View Figure 12 (g)). Merus flexor margin with 1 strong median spine, extensor margin with distal spine. Carpus, propodus and dactylus unarmed ( Figure 12 View Figure 12 (g)).
P1. Length 2.8 times PCL, with scattered short striae, and densely covered by uniramous long setae on merus, carpus, palm and fingers. Merus length subequal to PCL, 2.2 times as long as carpus, with strong mesial and distal spines, and scattered dorsal spines. Carpus 0.8 times as long as palm, 2.2 times as long as wide, dorsal surface with 2 irregular rows of 4–5 spines,mesial and lateral margins with 2–3 spines. Palm twice as long as wide, with spines in irregular longitudinal rows on mesial and lateral margins, dorsal surface unarmed. Fingers 1.3 times as long as palm; fixed finger with 2 well-developed lateral proximal spines; movable finger with 1 well-developed proximal spine on mesial margin ( Figure 12 View Figure 12 (h)).
P2–4. Missing.
Distribution
Andaman Sea, 202 m (present study) ( Figure 1 View Figure 1 ).
Remarks
The present specimen agrees with Leiogalathea laevirostris ( Balss, 1913) in having 4–6 rudimentary teeth on the rostral lateral margin and the unarmed posterior margin of the carapace ( Rodriguez-Flores et al, 2019).
Nevertheless, the following discrepancies prevent us from referring our specimen to L. laevirostris :
(1) Ventrally deflected rostrum, 1.2 times as long as wide, length 0.4 times PCL (vs horizontal rostrum, 1.5 times as long as wide, length 0.3 times PCL in L. laevirostris );
(2) Thoracic sternite 3 4.4 times as wide as long, anterolaterally produced, with distinct median notch flanked by 2 shallow lobes (vs sternite 3 3.0 times as wide as long, slightly produced anterolaterally, with shallow median notch in L. laevirostris );
(3) Thoracic sternite 4 2.4 times as wide as sternite 3, 2.5 times as wide as long (vs sternite 4 3.3 times as wide as sternite 3, 2.2 times as wide as long in L. laevirostris );
(4) P1 carpus 2.2 times as long as wide (vs 1.6 times in L. laevirostris );
(5) P1 fingers 1.3 times as long as palm (vs subequal to palm length in L. laevirostris ).
The present specimen also resembles L. evander Rodriguez-Flores, Macpherson and Machordom, 2019 in the similar rostral armature and direction, the proportion of the carapace and of P1. However, it exhibits some discrepancies that prevent us from assigning it to L. evander , as follows:
(1) Carapace with longer transverse ridges laterally on posterior branchial regions, lateral margins sinuous (vs short, laterally interrupted ridges on posterior branchial regions, lateral margins slightly convex in L. evander );
(2) Thoracic sternite 3 4.4 times as wide as long (vs 2.6–2.8 times in L. evander );
(3) P1 covered with long setae, merus length subequal to PCL, carpus with 2 rows of 4 spines each on dorsal surface (vs P1 lacking setae, merus length 0.7 times PCL, carpus with 1 or 2 dorsal spines, in L. evander ).
Although our specimen possibly represents an undescribed species of Leiogalathea , it is far from a complete condition, lacking antennules, antennae and P2–4. A formal description is deferred in the hope of collection of additional material.
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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Galatheoidea |
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