Typhlonida milindi Periasamy & Kurian & Ingole 2023, sp. nov.
Creators: name: Periasamy, Rengaiyan
name: Kurian, Palayil John
name: Ingole, Baban
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Munididae
Typhlonida
Typhlonida milindi

description: Typhlonida milindi sp. nov.
Figs 5–7
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.
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).
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).
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).
Eye very small eyes; maximum corneal diameter 0.18× distance between anterolateral spines (Figure 6A).
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).
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).
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).
Telson with few striae; greatest width 1.2× median length; anterolateral margin weakly concave (Figure 6F).
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).
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). 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).
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). The average K2P distance between the morphologically closest Typhlonida tiresias (AY351014) 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.
description: Published as part of 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, pp. 165-178 in Zootaxa 5231 (2) on pages 171-175, DOI: 10.11646/zootaxa.5231.2.3, http://zenodo.org/record/7575272