Typhlonida milindi, Periasamy & Kurian & Ingole, 2023

Periasamy, Rengaiyan, Kurian, Palayil John & Ingole, Baban, 2023, Two new deep-water species of squat lobsters (Crustacea: Anomura: Galatheoidea) from the Central and Southwest Indian Ridge, Zootaxa 5231 (2), pp. 165-178 : 171-175

publication ID	https://doi.org/ 10.11646/zootaxa.5231.2.3
publication LSID	lsid:zoobank.org:pub:96AF8399-24E2-4B26-8BE0-41013C04C6D6
DOI	https://doi.org/10.5281/zenodo.7575304
persistent identifier	https://treatment.plazi.org/id/038C2700-FFAD-FF88-FF2A-B9FDFDE8FC4C
treatment provided by	Plazi
scientific name	Typhlonida milindi
status	sp. nov.

Treatment

Typhlonida milindi View in CoL sp. nov.

Figs 5–7 View FIGURE 5 View FIGURE 6 View FIGURE 7

Material examined: Female holotype: NCPOR /HYD-CIR/0048, ♀ (CL 8.6 mm, PCL 3.2 mm), Seamount of the Southwest Indian Ridge, Indian Ocean, R / V ‘ MGS Sagar’ cruise MGS35 (Station No: MGS35C–BD5A), 02 April 2020, 26° 21′ 10.8′′ S, 67° 41′ 27.6′′ E, 2070 to 2404 m, Benthic Sledge, Coll. Periasamy R, samples in 90% ethanol GoogleMaps .

Ecological note: The specimen was collected along with associated benthic communities of deep-sea fish, glass sponge, and coral in the ferromanganese (Fe–Mn) covered basalt rocky with a thickness of 2–4 cm.

Distribution: Typhlonida milindi sp. nov. is known for its type locality in the seamount of the SWIR.

Etymology: It is named in honor of our senior scientific colleague — Late Dr. Milind Wakadikar, who contributed diligently to accomplish the objectives of the Indian deep-sea mission, especially the deepsea hydrothermal exploration program.

Description: Moderately small species, carapace as long as the width. Dorsal surface with main transverse ridges, without secondary transverse striae between main ridges, and striae lined with short; non-iridescent setae. Epigastric region with 2 pairs of spines, without a median row of spines behind the rostrum. Cervical groove deep; a hepatic region without spines on the dorsal surface. The anterior part of the branchial region between the cervical groove and post-cervical groove with 2 or 3 short tuberculate ridges and often 1 small spine anteriorly, posterior part of the branchial region with 5 transverse ridges excluding posterodorsal ridge. The cardiac region with 2 main transverse ridges. An intestinal region without striae; posterodorsal ridge distinct; without secondary stria. Front margin oblique; inclined posteriorly at 115° from the midline. Lateral margin slightly convex; anterolateral spine very small; far from reaching sinus between rostrum and supraocular spine; 5 spines branchial lateral or margin ( Figure 6A View FIGURE 6 ).

Rostrum spiniform; 0.6× PCL; supraocular spine 0.26× length of the rostrum; exceeding eyes. Epistomial ridge straight ending at antennal gland, mesial protuberance different ( Figure 6A View FIGURE 6 ).

Abdominal tergites unarmed; one transverse continuous stria on the second abdominal segment; without striae from the third to fifth segments.

Thoracic sternum sternal surface smooth; sternite 4 with only a few striae. Sternite 3 0.3× width of sternite 4. Sternite 4 anterior margin triangular; narrowly contiguous with sternite 3. Mid-length of the sternal plastron (sternites 4–7) 0.5× width of sternite 7 ( Figure 6E View FIGURE 6 ).

Eye very small eyes; maximum corneal diameter 0.18× distance between anterolateral spines ( Figure 6A View FIGURE 6 ).

Antenna peduncle article 1 distomesial spine almost reaching the distal margin of article 2. Article 2 distomesial spine reaching distal margin of article 3; distolateral spine not reaching midlength of article 3. Articles 3 and 4 unarmed ( Figure 6B View FIGURE 6 ).

Antennule peduncle basal article (distal spines excluded) overreaching corneae; distolateral spine much longer than distomesial spine; 2 lateral spines, proximal smaller; longer lateral spine not reaching the end of distolateral spines ( Figure 6C View FIGURE 6 ).

Third maxilliped surface smooth; ischium with a small distal spine on extensor margin; ischium as long as merus length. Merus with small median spine; carpus; propodus and dactylus unarmed ( Figure 6D View FIGURE 6 ).

Telson with few striae; greatest width 1.2× median length; anterolateral margin weakly concave ( Figure 6F View FIGURE 6 ).

P1 length 2.4–3.2× PCL; covered in rows of short plumose setae. Merus length 0.9–1.1× PCL; with a row of 2 large spines and 2 small spines on dorsal margin; 1 strong spine on dorsolateral margin; 4 spines on mesial margin; distomesial spine not reaching midlength of the carpus. Carpus length 0.5× merus; length 3× width, with 6 spines along the mesial margin. Propodus 1.3× merus length; palm with a row of 3 or 4 spines on the dorsal surface of the palm; fingers 0.4–0.5× total propodus length; without spines on outer margins ( Figure 7 View FIGURE 7 ).

P2–4 long and slender; with few small scales on lateral sides of meri and carpi; extensor margin with short plumose setae and few longer setae. P2 1.8–2.3× PCL; merus 0.7–0.8×PCL; length 8× width; 3.0× carpus length; 1.5× propodus length; extensor margin with 5–7 spines; flexor margin with 3 spines; well-developed distal spine; carpus extensor margin with the spine at midlength and a distal end; flexor margin with distal spine; propodus length about 8×height; with 5 movable flexor spines on flexor margin; dactylus gently curved distally; 0.6–0.7× propodus length, length about 7× height, extensor margin densely lined with stiff short setae on distal half; flexor margin armed along the entire length with 10–12 movable spines including spine at the base of unguis ( Figure 7F View FIGURE 7 ). The end of P2 carpus does not reach the end of P1 merus. P3 with similar spination and article proportions as P2; merus 0.9× P2 merus length; propodus; and dactylus as long as those of P2. P4 length 0.7–0.8× P2 length, merus length 0.3–0.5× PCL; propodus and dactylus similar in length to those of P3; merocarpal articulation reaching hepatic marginal spine carapace ( Figure 7 View FIGURE 7 ).

Colour in life: carapace pink anteriorly fading to white at posterior; abdominal somite 2 white; somites 3–6 pink, P1 and P2–4 white.

Genetic data: DNA sequencing for this species was successful for mtCOI gene (Accession numbers: COI: OP311615 View Materials ). The average K2P distance between the morphologically closest Typhlonida tiresias ( AY351014 View Materials ) and the SWIR specimen was 0.04% for COI .

Remarks: The SWIR new species is the closest relative of Typhlonida tiresias ( Macpherson, 1994) and T. parvioculata ( Baba, 1982) . The new species from SWIR can be differentiated from Typhlonida tiresias by gastric region with a row of epigastric spines, extensor border of merus of the third maxilliped, and the shape of the sternite 3. While T. parvioculata has a second abdominal segment with 2 to 4 spines anteriorly, a third maxilliped merus elongates with 2 prominent inner marginal spines of subequal size: one distal and another proximal to midlength and not in Typhlonida milindi sp. nov.