Tirmilyra sagittifera (Alcock, 1896) n. comb.

(Figs. 1A–D, 2A, B, 3A, B, 4A–D)

Ebalia sagittifera Alcock, 1896: 186 (in key), 188, 189— Alcock & Anderson 1897: pl 29, fig 9— Apel 2001: 50.

Ebalia? Sagittifera — Titgen, 1982: 113, 247 (in list)— Cooper 1997: 173, 174, fig 7.

Philyra rectangularis — Stephensen, 1946: 87, 88, fig 15a, b— Guinot 1967: 249 (in list)— Basson et al. 1977: 250.

Philyra concinnus — Ghani & Tirmizi, 1995: 143–147, fig 2a–e (in part, material from Persian Gulf).

Philyra sagittifera — Ng et al. 2008: 93 — Galil 2009: 281, tab 1— Naderloo & Türkay 2012: 32 — Naderloo 2017: 112, figs. 14.35d, 14.38, 14.41.

Type material. Lectotype (herein selected): ZSI C910/10, male (CL 5.0 mm, CW 4.5 mm), Karachi, Pakistan, coll. F. W. Townsend. Paralectotype: ZSI C910/10, female (CL 6.0 mm, CW 5.7 mm), same data as lectotype.

Other material examined. Persian Gulf: ZUMC CRU885, 1 male (CL 4.2 mm, CW 3.9 mm), 6 m depth, Bushehr, Iran, 03.03.1993, coll. G. Thorson; ZMUC CRU-885, 2 males, 3 ovigerous females, 6 m depth, Bushehr, Iran, 03.03.1993, coll. G. Thorson; ZUTC 1339, 1 juvenile, muddy-sandy flat, E of Bandar-Abbas, Iran, 27°11′N, 56°21′E, coll. Reza Naderloo, Abbas Kazemi; ZUTC 1340, 1 male, muddy flat, E of Bandar-Khamir, Iran, 27°56′N, 55°36′E, coll. Reza Naderloo; SMF, 1 male, 3 juveniles (), N. of Al-Khobar, Tarut Bay, Saudi Arabia, 19.03.1993, coll. Michael Apel; SMF, 8 males, 6 ovigerous females, N. of Al-Khobar, Tarut Bay, Saudi Arabia, 25.03.1993, coll. Michael Apel; SMF, 1 juvenile, intertidal, N. of Jubail, Saudi Arabia, 30.04.1993, coll. Michael Apel; SMF, 1 male, 6 m depth, Qurmah Channel, N. of Jubail, Saudi Arabia, 05.10.1992, coll. Michael Apel.

Description. Carapace hexagonal (Fig. 1A, B), slightly longer than broad. Dorsal surface smooth, three broad tuberculated and granular ridges, uniting to form "broad-arrow" point directed forward, median ridge from progastric region to intestinal region; lateral ridges extending backwards and downwards to branchial region, parallel to anterolateral margins with their ends projecting beyond postero-lateral borders in forming broad granular denticles; regions relatively distinct, with elevated gastric, cardiac, branchial, intestinal regions; hepatic region excavated, forming depression; upper, lower margins beaded, originating from middle of anterolateral margin, not merging anteriorly, broadly triangular tooth projecting on anterior half of lower margin of anterolateral border (Fig. 1A, B); anterolateral margin merging with posterolateral with broad triangular tooth; anterolateral, posterolateral, posterior margins beaded; epibranchial junction with right angle; posterolateral margin slightly sinuous, convex (Fig. 1A, B); front bilobed; epistome visible beyond frontal margin from dorsal view; posterior margin convex, lateral sides with knob-like dorsoventrally flattened teeth with rounded tips, small median tooth on posterior margin (Fig. 1A, B). Anterior margin of endostome almost reaching as far forwards as inhalent channels.

Maxilliped 3 (Figs. 1D, 4A) smooth, entirely covering endostome; merus with notch, 0.9× as long as ischium along inner margin; ischium 1.4× longer than wide; propodus, dactylus not visible in external view when reposed, articulating on inner surface of merus. Exopod outer margin convex, setose, much longer than wide, almost twice as long as merus.

Chelipeds (Fig. 1A, B) equal, longer than half of carapace length, granulated. Merus triquetral in cross-section with edges raised, granular; both inner, outer margins with tuberculated ridge, tubercles larger on inner margin, patch of tubercles on upper proximal and distal end. Carpus, propodus have raised row of granules along inner edge of upper surface. Fingers slender, about two-thirds length of propodus, occlusal margins of fingers toothed, with scattered setae, median shallow canal extending to distal length in both fingers.

P2–P5 (Fig. 1A, B) subcylindrical; total length of all pairs almost similar, merus, carpus glabrous, merus longest; carpus, propodus almost equal in length; dactylus with tapering distal end.

Thoracic sternum (Fig. 1D) tuberculated, slightly concave, tubercules prominent at margins. Sternites 1–3 completely fused without any trace of sutures; sternite 3 separated from sternite 4 by shallow groove; sternite 4–6 almost similar in width; sternite 7 completely tuberculated.

Male pleon long, narrow (Fig. 1D), smooth, with three articulating parts (Fig. 1D, 4B): somite 1 free, narrow; somites 2–6 fused, immovable, partial suture visible between somites 5–6, posterolateral angles with small bulge, somite 6 without denticle; telson triangular, longer than broad, with curved apex.

Female pleon ovate; somite 1 free; somites 2–6 fused, suture clearly visible between somites 2 and 3, partial suture visible between somites 3–4 and 5–6, forming domed plate almost completely covering thoracic sternum. Telson longer than broad, with curved apex (Fig. 2B).

G1 (Fig. 4A–D) shaft long, slender, straight, apical process long, about 0.3 times as long as whole length, slightly sinuous-shape, with tapering ending, apical lobe with setae shorter than the length of the tip. Female gonopore (Fig. 5B) on inner anterior edge of sternite 5, oval in shape with narrow opening.

Variation. The carapace of female resembles with that of male, except for lateral sides of posterior margin having smaller knob-like dorsoventrally flattened teeth, small median tooth on posterior margin less pronounced or absent (Fig. 2A).

Distribution. The species is recorded so far from Pakistan (Alcock 1896), the Persian Gulf [Stephensen (1946) as Philyra rectangularis; Basson et al. (1977) as P. rectangularis; Titgen (1982) as Ebalia sagittifera; Cooper (1997) as E. sagittifera; Apel (2001) as E. sagittifera; Naderloo and Türkay (2012); Nadeloo (2017)] and the Gulf of Oman (Naderloo et al. 2015).

Remarks. The fresh specimens collected from the Persian Gulf agree with the lectotype of T. sagittifera n. comb. The male specimen collected from the Persian Gulf (Fig. 1A) differs from the lectotype male by having smaller blunt teeth on the lateral sides of posterior margin as well as prominently swollen cardiac region. These differences can be attributed to differences in the body size of the male specimens.

Tirmilyra sagittifera n. comb. closely resembles its congener T. concinnus n. comb., but they can be differentiated on the basis of the following characteristics: dorsal surface of carapace without denticle on the metagastric region (Fig. 1A, B, D) (versus denticle present on the metagastric region of carapace in T. concinnus n. comb., Fig. 1E; Ghani & Tirmizi 1995: Fig. 1A); posterior margin slightly convex (Fig. 1A, B, D) (versus straight in T. concinnus n. comb., Fig. 1E; Ghani & Tirmizi 1995: Fig. 1A); posterior margin bearing median tooth in males (Fig. 1A, B, D) (versus median tooth absent in males in T. concinnus n. comb., Fig. 1E; Ghani & Tirmizi 1995: Fig. 1A); blunt teeth present on the lateral sides of posterior margin (Figs. 1A, B, D) (versus pointed teeth on lateral sides of posterior margin in T. concinnus n. comb., Fig. 1E; Ghani & Tirmizi 1995: Fig. 1A); thoracic sternum tuberculated, prominent at margins (Fig. 1C) (versus thoracic sternum smooth, tuberculation only on margins in T. concinnus n. comb., Fig. 1F); male G1 apical process comparatively long (0.3× as long as whole length), slightly sinuous-shape, with tapering ending (Fig. 4A–D) (versus apical process comparatively short (0.2× as long as whole length), more sinuous-shape, with spatulate ending in T. concinnus n. comb., Fig. 4E, F; Ghani & Tirmizi 1995: Fig. 1E, F), endostome almost reaching inhalent channels (Fig. 5A) (versus endostome reaching slightly beyond inhalent channels in T. concinnus comb. nov. Fig. 5C)