Alpheus tigrinus, Anker, 2024

Anker, Arthur, 2024, Preliminary revision of Alpheus djeddensis Coutière, 1897 species complex, with description of three new species of goby-associated snapping shrimps and taxonomic notes on A. macellarius Chace, 1988 and A. djiboutensis De Man, 1909 (Decapoda: Alpheidae), Zootaxa 5472 (1), pp. 1-63 : 30-41

Alpheus tigrinus sp. nov.

Figs. 18–23 , 24A–E

(+ Alpheus cf. tigrinus : Figs. 25A, B ; Alpheus aff. tigrinus : Figs. 24F, G , 25C–G )

Alpheus djiboutensis . — Luther 1958a: 175, figs. 1–3; Luther 1958b: 144; Holthuis 1958: 25, fig. 9; Debelius 2001: 152 (part.), 2 colour photographs [small photograph = A. tigrinus sp. nov.; large photograph = A. aff. tigrinus , see text] [not A. djiboutensis De Man, 1909 ].

Alpheus djeddensis. — Dehghani et al. 2019: 483, fig. 2C, D [not A. djeddensis Coutière, 1897 ].

(?) Alpheus djeddensis sensu lato. — Anker & De Grave 2016: 350, fig. 8 [not A. djeddensis Coutière, 1897 , probably = A. aff. tigrinus , see text].

(?) Alpheus sp. cf. djiboutensis . — Anker 2000: 5, fig. 6 [not A. djiboutensis De Man, 1909 , = A. aff. tigrinus , see text].

(?) Alpheus sp. — Karplus & Thompson 2011: 591, fig. 4.4.10D [= A. aff. tigrinus , see text].

(?) Alpheus sp. A .— Senou et al. 2004: 300, colour photograph [probably = A. aff. tigrinus , see text].

(?) Alpheus sp. 3 .— Minemizu 2013: 102, colour photograph [= A. aff. tigrinus , see text].

(?) Alpheid shrimp. — Randall et al. 1998: 399, upper photograph [probably = A. aff. tigrinus , see text].

(?) Alpheid shrimp. — Randall 2005: 527, upper photograph [probably = A. aff. tigrinus , see text].

Type material. Holotype: male (cl 15.3 mm), FLMNH UF 37012 , Red Sea , Saudi Arabia, Farasan Islands, Zahrat Durakah (Zahirah), 16°50’09.2”N / 42°18’22.7”E, fringing reef / slope, depth 2–6 m, leg. A.Anker et al., 11.03.2013 (BDJRS-2702) . Paratypes: 1 male (cl 12.1 mm), FLMNH UF 37014 , same collection data as for holotype (BDJRS-2704) ; 1 male (cl 15.4 mm), FLMNH UF 37015 , same collection data as for holotype (BDJRS-2705) ; 1 male (cl 11.4 mm), FLMNH UF 37001 , same collection data as for holotype (BDJRS-2688) ; 1 male (cl 14.8 mm), FLMNH UF 37017 , same collection data as for holotype (BDJRS-2707) ; 1 female (cl 13.7 mm, missing minor cheliped), FLMNH UF 48760 , Red Sea , Saudi Arabia, Farasan Islands , Zahrat Durakah ( Zahirah ), 16°50’06.0”N / 42°18’21.6”E, coral reef, 0–25 m, leg. D. Uyeno & M.L. Berumen, 28.10.2014 (BDJRS-6334); 1 ovig. female (cl 16.7 mm), FLMNH UF 36648 , Red Sea , Saudi Arabia, Farasan Islands, Tiger Head Island, 16.7910, 42.1987, karstic shore and fringing reef, depth 1–6 m, leg. A. Anker et al., 10.03.2013 (BDJRS-1767) ; 1 male (cl 17.4 mm, missing major cheliped), FLMNH UF 36943 , same collection data as for previous paratype (BDJRS-2564) ; 1 male (cl 13.0 mm), FLMNH UF 36957 , same collection data as for previous paratype, in burrow together with Cryptocentrus caeruleopunctatus (BDJRS-2585) ; 1 male (cl 14.5 mm), FLMNH UF 36905 , Red Sea , Saudi Arabia, Farasan Islands , Abulad (Abu Lad), 16°47’51.7”N / 42°11’56.8”E, fringing reef / slope, depth 1–10 m, leg. A. Anker et al., 10.03.2013 (BDJRS-2435) ; 1 male (cl 16.0 mm), FLMNH UF 36906 , same collection data as for previous paratype (BDJRS-2436) .

Other material examined. 1 female (cl 9.4 mm), FLMNH UF 48648 , Red Sea, Saudi Arabia, Farasan Islands , North Ghorab Island, 17°06’32.4”N / 42°04’08.4”E, silty fringing reef, depth 5–7 m, leg. D. Uyeno et al., 22.10.2014 (BDJRS-5831); 1 male (cl 9.7 mm), 1 ovig. female (cl 14.3 mm), RSRC, Red Sea, Saudi Arabia, Thuwal , KAUST, near King Abdullah Monument, 22°20’32.2”N / 39°05’03.1”E, sandflat with rubble and sparse seagrass near channel, depth 0.5–1 m, suction pump, in burrow, leg. A. Anker , 24.09.22 (AA-22-239); 1 young female (cl indet., photographed and released), Red Sea, Saudi Arabia, Rabigh , northern end of flat desert peninsula 1 km south of coast guard station, 22°56’14.7”N / 38°50’55.1”E, hard bottom (rocky platform) with sandy patches, depth 0.3–1 m, suction pump, in burrow, leg. A. Anker , 18.10.22 (AA-22-406); 1 female (cl 15.0 mm), RMNH. CRUS.D.14302, Red Sea, Sudan, Port Sudan, depth 1.5–3 m, in burrow in sand, leg. W. Luther.

Alpheus cf. tigrinus . 1 male (cl 14.3 mm, missing minor cheliped), FLMNH UF 71625 , United Arab Emirates, Abu Dhabi, Sir Bani Yas Island , sta. AD23-003, 24°22’04.8”N / 52°35’56.4”E, leg. A. Uehling et al., 16.06.2023 (ARAD-0104).

Alpheus aff. tigrinus . 1 young female (cl 5.8 mm), OUMNH. ZC.2014-11-038, Singapore, CMBS sta. YB188, St. John’s Island , DRTech northern lagoon, depth 0–0.5 m, sand patchily mixed with rubble, suction pump, leg. A. Anker, 05.06.2013 (SS-4529).

Diagnosis. Morphology largely as in A. djeddensis . Carapace strongly pitted, except for mid-dorsal portion, covered with short setae; anterolateral surface with several longer stiff setae ( Fig. 18A, B ). Rostrum well developed, usually reaching well beyond mid-length of first article of antennular peduncle, sometimes almost reaching its distal margin; rostral carina distinct, blunt, raising above orbital hoods, extending well beyond base of orbital hoods, not reaching mid-length of carapace; orbital hoods unarmed, rounded; adrostral furrows shallow ( Figs. 18A, B , 20B, C , 23A, D , 24C ). Rostro-orbital region moderately protruding beyond anterolateral margin of carapace ( Figs. 18A, B , 23A, D ). Telson broad, about twice as long as wide at base, gently constricted near posterior third, tapering; dorsal surface faintly pitted, with two pairs of stout spiniform setae inserted at some distance from lateral margins; posterior margin broadly rounded, with row of slender spiniform setae between two pairs of more robust spiniform setae at each distolateral angle, mesial much longer than lateral ( Figs. 18C , 23B , 24D ). Antennule with stylocerite swollen laterally, its tip falling well short of distal margin of first article of peduncle, ventromesial carina with subtriangular tooth; second article about 2.7 times as long as wide ( Figs. 18A, B, D , 23A, D , 24C ). Antenna with distoventral margin of basicerite armed with acute tooth; scaphocerite with lateral margin faintly concave; distolateral tooth slightly or distinctly overreaching distal margin of blade ( Figs. 18A, B , 23A, D , 24C ). Third maxilliped with penultimate article cup-shaped, widening distally, moderately convex ventrally, with some moderately elongate setae on distoventral margin ( Fig. 18E ). Major cheliped of brevirostris type; merus stout, without tooth on distomesial margin, ventromesial margin with some spiniform setae; chela not elongate; palm about 1.7–1.9 times as long as wide, with deep transverse groove on dorsal margin, mesial surface faintly granulated; fingers about 0.6 length of palm; plunger of dactylus not bulging ( Figs. 19A–D, H , 20D, E , 23C, E ). Minor cheliped distinctly shorter and weaker than major cheliped; merus without tooth on distomesial margin, ventromesial margin with some spiniform setae; chela not elongate; palm about 1.7–1.8 as long as wide, without grooves, mesial surface faintly granulated; fingers about 1.2–1.4 times as long as palm, somewhat gaping, typically not sexually dimorphic, with rows of balaeniceps setae on each side of dactylus and pollex in males and usually also in females, occasionally absent in females ( Figs. 19E–G, J , 20F–H , 23C ). Second pereiopod with ratio of carpal subarticles equal to 3.0 / 2.5 / 1.0 / 1.0 / 1.5 ( Fig. 18F ). Third pereiopod moderately slender; ischium armed with stout spiniform seta; merus about 4.5 times as long as maximal width, unarmed; propodus with seven or so spiniform setae along ventral margin and one pair of spiniform setae on distoventral angle; dactylus about 0.45 length of propodus, gradually curving distally, spatulate ( Fig. 18G–I ). Fifth pereiopod ischium armed with spiniform seta ( Fig. 18J ). Appendix masculina with stiff setae on apical part and along margin opposed to endopodal ramus ( Fig. 18L ). Uropodal exopod with diaeresis almost sinuous, with broad lateral lobe; endopod with row of spiniform setae on distal margin ( Fig. 18M ). Colour pattern diagnostic, as described below.

Colour pattern. Background colour whitish to pale yellow; carapace with several transverse (dorsally) and more oblique (laterally), red-brown bands; most bands with well-defined edges and without colourless areas within; anterolateral bands on each side of orbital hoods reddish brown; carapace flanks of larger individuals with large dark brown patch closer to posterior edge (absent in smaller individuals); rostrum whitish or yellowish; post-rostral area typically with large dark brown patch between eyes; pleon with conspicuous transverse banding consisting of one complete posterior band running across each pleonite and one incomplete anterior band occupying only anterodorsal section of each pleonite; saddle on first pleonite conspicuous, white with bright yellow markings; saddle on fourth pleonite less conspicuous, much smaller, yellowish; telson with anterior half largely white or white with yellowish tinge, often with two red-brown spots, and with posterior half dark brown, except white spots around spiniform setae; antennular peduncles yellow with orange-brown second article; stylocerite yellow with narrow orange-brown band along lateral edge; antennal carpocerite and scaphocerite mainly yellow, each with large orange-brown patch, that of scaphocerite occupying most of lateral surface near its mid-length; antennular and antennal flagella bright yellow, with orange tinge; chelipeds with pale blue or whitish background colour and dark purple-brown or brown-green patches on merus, most of carpus and mesial face of palm of chela, in latter case largely interconnecting; distodorsal surface of palm with small orange area near articulation with dactylus; pollex and dactylus with similar pattern as on palm on proximal half, calcified distal portion whitish with pale pink or orange tinge; lateral face of chelae with similar patches as on mesial face, sometimes with more intense blue tinge; second to fifth pereiopods largely blue with bright yellow articulations; uropods dominated by blue and yellow colour, with some dark brown or purple-red areas; eggs in ovigerous females green ( Figs. 21–23 , 24A–E ). See also Figs. 24F, G , 25 for colour patterns of A. cf. tigrinus and A. aff. tigrinus .

Etymology. The new species’ name ( tigrinus , related to or striped like a tiger) refers to its highly contrasting transverse banding; used as an adjective.

Common name. Tiger goby shrimp.

Type locality. Farasan Islands , Red Sea coast of Saudi Arabia .

Distribution. Western Indian Ocean: presently known with certainty only from the Red Sea ( Egypt, Israel, Saudi Arabia, Eritrea); highly likely also present in the Arabian-Persian Gulf ( Kuwait, UAE, Qatar, Iran; tentatively as A. cf. tigrinus , see below). Material or photographic records from other Indo-West Pacific localities ( Singapore, Indonesia, Taiwan, etc.) more likely refer to a different species (tentatively as A. aff. tigrinus , see below).

Ecology. Near-shore sandflats, reef flats and sandy patches between coral stands, from the intertidal to at least 15 m; typically associated with the goby Cryptocentrus lutheri ( Luther 1958a, as “ C. octofasciatus oder eine andere von uns noch nicht bestimmte Art”; Debelius 2001: 152, smaller photograph; unpublished photographs from Al Birk, Saudi Arabia [pers. obs.]; see also Fig. 25A, B , as A. cf. tigrinus ); possible associations with C. caeruleopunctatus and C. cryptocentrus need confirmation.

Remarks. Alpheus tigrinus sp. nov. can be morphologically distinguished from A. djeddensis and A. shukran sp. nov. by the presence of several conspicuous, stiff, somewhat elongate setae on the anterolateral surface of the carapace, below each orbital hood ( Fig. 18A, B ); these setae are absent in A. djeddensis and A. shukran sp. nov. ( Figs. 3A, B , 4A, B , 12A ). Another morphological difference between these species lies in the proportions of the major and minor chelipeds, which are noticeably stouter in A. tigrinus sp. nov., with, for instance, the palm of the major chela being around 2.0 as long as wide (high) in A. tigrinus sp. nov. ( Fig. 19B, C, E, G, H ) vs. 2.5 times or more as long as wide in A. djeddensis ( Figs. 2C–H , 3F, G, J, K ) and 2.3 times in A. shukran sp. nov. ( Fig. 12C–F ). However, only adult specimens (with cl> 10 mm) with fully developed, non-regenerated chelipeds should be used in the comparison of the relative proportions of the chelipeds.

In both males and females of A. djeddensis and A. shukran sp. nov., the cheliped fingers possess low longitudinal crests furnished with dense rows of balaeniceps setae, including in relatively small specimens ( Figs. 1A , 2G, H , 3K, J , 5C–E , 7E , 9E, F , 12E, F ). In A. tigrinus sp. nov., all fully grown males also have well-developed balaeniceps crests ( Figs. 19G, E, I , 22B , 23C ), however, their development in females is less clear. The present material of A. tigrinus sp. nov., indicates that females of this species may not always have balaeniceps setae ( Figs. 19J , 20F–H , 21 , 24A ), although they seem to be present in all large females with normally developed, i.e., non-regenerated chelipeds, as in Holthuis’ (1958) female from Port Sudan ( Fig. 20F–H ). Other characters, such as the length of the distolateral tooth relative to the distal margin of the blade, seem to be variable ( Figs. 18A , 23A, D , 24C ), just like in A. djeddensis and A. shukran sp. nov. (see above and Figs. 1C , 3A , 4A , 8A , 9B , 12A , 13C, G , 14C ).

The major chelae of the female from Port Sudan and one of the males from the Farasan Islands are strongly curved mesially ( Figs. 20A , 23C ). A similar condition is found in the somewhat inadequately described A. cythereus Banner & Banner, 1966 , presently known only from the subsequently lost type specimen. However, A. cythereus differs from A. tigrinus sp. nov. and other species allied to A. djeddensis by the noticeably shorter second article of the antennular peduncle, the first carpal subarticle of the second pereiopod much shorter than the second, and the unarmed ischium of the third pereiopod (cf. Banner & Banner 1966: fig. 45A, G, H).

In life, A. tigrinus sp. nov. can be easily separated from A. djeddensis and A. shukran sp. nov. by several details of the colour pattern, such as the more contrasting banding dominated by dark red-brown colour (vs. with green-brown or blue tones in A. djeddensis and A. shukran sp. nov.); the carapace flanks with a large dark-brown area (vs. pale with some dark, obliquely descending bands in A. djeddensis and A. shukran sp. nov.); the bright yellow antennular and antennal flagella (vs. blue in A. djeddensis or pale greenish or yellowish in A. shukran sp. nov.); and the dorsal surface of the telson with whitish anterior half (typically with two brown-orange spots) and dark brown posterior half (vs. with a more mottled blue-brown-yellow patterns in A. djeddensis and A. shukran sp. nov.) (cf. Figs. 6–14 , 21–23 , 24A–E ). In addition, A. tigrinus sp. nov. seems to prefer C. lutheri as partner goby, whereas A. djeddensis typically associates with C. caeruleopunctatus and possibly with C. cryptocentrus (see above). Furthermore, A. tigrinus sp. nov. can be separated from A. macellarius and A. cf. macellarius using the same criteria as for A. djeddensis (see above), including several striking differences in the colour pattern (cf. Figs. 15–17 , 21–23 , 24A–E ).

The goby-associated snapping shrimps from the Arabian-Persian Gulf and the Iranian side of the Gulf of Oman, which have a colour pattern very similar to that A. tigrinus sp. nov. ( Fig. 25A–C ; Dehghani et al. 2019: fig. 2C, as A. djeddensis ; not fig. 2D, see below) are possibly conspecific with those from the Red Sea. The only such specimen from the Arabian-Persian Gulf presently available to the author is an adult male from Abu Dhabi (FLMNH UF 71625) missing its minor cheliped ( Fig. 25A ). This specimen agrees in all important features with the type specimens from the Red Sea, including the presence of elongate stiff setae on the anterolateral surface of the carapace, which appears to be the main diagnostic feature of A. tigrinus sp. nov. The geographical proximity of the Arabian-Persian Gulf to the Red Sea and common biogeographic patterns (e.g., Zajonz et al. 2022) would support the assumption that the Abu Dhabi specimen is conspecific with A. tigrinus sp. nov. In addition, photographic evidence suggests that in the Arabian-Persian Gulf shrimps associate with the same goby as A. tigrinus sp. nov. in the Red Sea, namely Cryptocentrus lutheri ( Fig. 25A, B ). On the other hand, the colour pattern of the Abu Dhabi specimen is not as bright as that of the Red Sea specimens and it also differs from them by the absence of a dark patch on the carapace flanks and orange (rather than yellow or orange-yellow) antennal flagella (cf. Fig. 21 , 22 , 25A ; see also Fig. 25B, C ). Therefore, the incomplete Abu Dhabi male, which was collected only recently (in June 2023, i.e., after the original submission of the manuscript), is tentatively assigned to A. cf. tigrinus , awaiting its molecular comparison with the Red Sea material. It must be noted here that one of the photographs in Dehghani et al. (2019: fig. 2D) was used by these authors by mistake and without proper photographic credits. This photograph shows the paratype female of A. tigrinus sp. nov. from Farasan Islands on the Red Sea coast of Saudi Arabia ( Fig. 21 ), and not “male pale morph (CL 9.8 mm)” of A. djeddensis from “Tis, Chabahar Bay” in Iran, as the legend claims (although a male specimen from this locality was listed under the material examined, see Dehghani et al. 2019: 483).

Outside of the western Indian Ocean, photo-vouchered material referrable to A. tigrinus sp. nov. or perhaps a closely related species is extremely scarce. The only specimen with a great similarity with A. tigrinus sp. nov. available for the present study is a young female (cl 5.8 mm) from Singapore ( Fig. 24F, G ), which was already reported by Anker & De Grave (2016) under A. djeddensis sensu lato. The Singaporean female has essentially the same colour pattern as the young female from Rabigh, Saudi Arabia ( Fig. 24E ), but lacks stiff elongate setae on the anterolateral region of the carapace (S. De Grave, pers. comm.). A thorough analysis of colour photographs taken in the “Coral Triangle” ( Malaysia, Indonesia, Philippines, Timor, Papua New Guinea) and adjacent areas of the western Pacific (southern Japan, Taiwan, eastern Australia), suggests the presence of at least one species closely related to A. tigrinus sp. nov., with a slightly different colour pattern. In this species, herein tentatively referred to as A. aff. tigrinus ( Fig. 25D–H ), the antennular and antennal flagella are bright orange (rather than yellow as in A. tigrinus sp. nov. from the Red Sea, with A. cf. tigrinus from the Arabian-Persian Gulf being somewhat intermediate); the carapace flanks are dark violet with large circular or oval spots (not with a large dark patch as in A. tigrinus sp. nov.); and the distodorsal area of the palm has a conspicuous, bright orange spot near the base of the dactylus (which is present, but much smaller in A. tigrinus sp. nov.). Furthermore, A. aff. tigrinus is most often seen together with Cryptocentrus nigrocellatus (Yanagisawa) , C. albidorsus (Yanagisawa) or C. leucostictus (Günther) ( Fig. 25D, E, G, H ; see also colour photographs in Randall et al. 1998: 399; Anker 2000: 5; Debelius 2001: 152, under A. djiboutensis , Bali; Randall 2005: 527; Kuiter & Debelius 2019: 152). The afore-mentioned young female from Singapore ( Fig. 24F, G ) is tentatively assigned to A. aff. tigrinus , although its colour pattern is clearly not fully developed.

In summary, based on presently available, largely photographic evidence, the two most likely taxonomic / biogeographic scenarios are: (1) A. tigrinus sp. nov. is endemic to the Red Sea and is replaced in the remaining parts of the Indian Ocean (including the Arabian-Persian Gulf), South-East Asia and western Pacific by one or two closely related species ( A. cf. tigrinus , A. aff. tigrinus ); and (2) A. tigrinus sp. nov. is restricted to the western Indian Ocean, extending from the Red Sea to the Arabian-Persian Gulf (including material herein identified as A. cf. tigrinus ), and is represented by at least one closely related species ( A. aff. tigrinus ) in South-East Asia and western Pacific). The more numerous similarities of the colour patterns between the shrimps from the Red Sea ( A. tigrinus sp. nov.) and those from the Arabian-Persian Gulf ( A. cf. tigrinus ), combined with the presence of at least one diagnostic feature of A. tigrinus sp. nov. in the Abu Dhabi specimen (see above), and analogous biogeographic patterns observed in numerous other taxa, including its preferred partner goby, Cryptocentrus lutheri ( Eagderi et al. 2019) , would favour the second scenario. The third scenario, i.e., A. tigrinus sp. nov. having a wide Indo-West Pacific distribution, ranging from the Red Sea to Japan and Indonesia, and perhaps cooccurring with a closely related species in the “Coral Triangle”, is less likely, but cannot be totally excluded at this stage. Any of these hypotheses can be tested only after sequencing material of A. cf. tigrinus from the Arabian-Persian Gulf and collecting, examining and sequencing material of A. aff. tigrinus and other closely related forms from the “Coral Triangle” (see also below).

Figures

FIGURE 1. Historical illustrations of Alpheus djeddensis Coutière, 1897 [A–C] and Alpheus djiboutensis De Man, 1909 [D–K]: A, right (minor) chela, mesial; B, carapace and frontal appendages, dorsal; C, antennal scaphocerite, dorsal; D, carapace and frontal appendages, dorsal; E, antennal scaphocerite, distal half, dorsal; F, telson, dorsal; G, left (major) cheliped, lateral; H, right (minor) cheliped, lateral; I, same, chela, dorsal; J, second pereiopod, lateral; K, third pereiopod, lateral. After Coutière (1899) [A, B] and De Man (1909) [C–K].

FIGURE 2. Alpheus djeddensis Coutière, 1897, lectotype, female (cl 20.5 mm) from Jeddah, Saudi Arabia (RMNH.CRUS. D.1781); A, body, lateral; B, frontal region, dorsal; C, left (major) cheliped, mesial; D, same, distal portion of merus, carpus and chela, mesial; E, same as C, lateral; F, right (minor) cheliped, mesial; G, same, carpus and chela, lateral; H, same, distal portion of merus, carpus and chela, mesial; I, telson, dorsal; J, original label. All photographs by the author, except for I (courtesy of C.H.J.M. Fransen). Refer to A, C, F for scale.

FIGURE 3. Alpheus djeddensis Coutière, 1897, paralectotype, male (cl 18.9 mm) from Jeddah, Saudi Arabia (MNHN-IU-2016- 9011); A, frontal region, dorsal; B, same, lateral; C, telson, dorsal; D, antennal scaphocerite, dorsal; E, third maxilliped, lateral; F, left (major) cheliped, mesial; G, same, lateral; H, same, dactylus, lateral; I; right (minor) cheliped, ischium to proximal portion of propodus (chela palm), lateral; J, same, distal portion of merus carpus and chela, lateral; K, same, chela, mesial; L, second pereiopod, lateral; M, third pereiopod, lateral; N, same, propodus and dactylus, lateral; O, same, dactylus, ventromesial; P, fourth pereiopod, lateral; Q, same, propodus and dactylus, lateral.

FIGURE 4. Alpheus djeddensis Coutière, 1897, male (cl 19.3 mm) from Farasan Islands, Saudi Arabia (FLMNH UF 36913); A, frontal region, dorsal; B, same, lateral; C, telson, dorsal; D, tooth on ventromesial carina of first article of antennular peduncle, lateral; E, third maxilliped, lateral; F, same, distal portion of antepenultimate article, and penultimate and ultimate articles, ventrolateral (setae omitted); G, second pereiopod, distal portion of merus, carpus and chela, lateral; H, third pereiopod, lateral; I, same, propodus and dactylus, lateral; J, same, dactylus, ventrolateral; K, fifth pereiopod, lateral; L, same, propodus and dactylus, lateral.

FIGURE 5. Alpheus djeddensis Coutière, 1897, male (cl 19.3 mm) from Farasan Islands, Saudi Arabia (FLMNH UF 36913); A, left (major) cheliped, carpus and chela, lateral; B, same, dactylus, lateral; C, right (minor) cheliped, lateral; D, same, mesial; E, same, distal portion of merus, carpus and chela with fingers open, lateral.

FIGURE 6. Alpheus djeddensis Coutière, 1897, male (cl 19.3 mm) from Farasan Islands, Saudi Arabia (FLMNH UF 36913); A, shrimp post-mortem (carapace damaged during collection), dorsal; B, same, lateral. Photographs by the author.

FIGURE 7. Alpheus djeddensis Coutière, 1897, male (cl indet.) from Thuwal, Saudi Arabia (specimen kept alive in RSRC); A, shrimp alive, dorsal; B, same, lateral. Photographs by the author.

FIGURE 8. Alpheus djeddensis Coutière, 1897, male (cl indet.) from Thuwal, Saudi Arabia (specimen kept alive in RSRC) [A–F]; major cheliped and third pereiopod (RSRC, used for DNA sequencing) [G]; A, frontal region, dorsal; B, tail fan, dorsal; C, left (major) chela, mesial, D, same, lateral; E, right (minor) cheliped and second pereiopod, lateral; F, right (minor) chela, lateral; G, major cheliped, mesial, and third pereiopod, lateral. Photographs by the author.

FIGURE 9. Alpheus djeddensis Coutière, 1897, female (cl indet.) from Thuwal, Saudi Arabia (specimen kept alive in RSRC); A, shrimp alive, dorsal; B, frontal region, dorsal; C, right (major) chela, mesial; D, left (minor) chela, distal portion of palm and fingers, mesial. Photographs by the author.

FIGURE 10. Alpheus djeddensis Coutière, 1897, in situ photographs; A, shrimp (ovigerous female) near burrow entrance, together with Cryptocentrus caeruleopunctatus (Rüppell) (goby not in frame and out focus), near Thuwal, Saudi Arabia; B, shrimp (sex unknown) outside of its burrow, together with C. caeruleopunctatus, southern Egypt. Photographs courtesy of Viktor Nunes Peinemann [A] and Ülar Tikk [B].

FIGURE 11. Alpheus shukran sp. nov., holotype, ovigerous female (cl 18.5 mm) from Masirah Island, Oman (FLMNH UF 71923); A, shrimp alive, dorsal; B, same, lateral. Photographs by the author.

FIGURE 12. Alpheus shukran sp. nov., holotype, ovigerous female (cl 18.5 mm) from Masirah Island, Oman (FLMNH UF 71923); A, frontal region, dorsal; B, tail fan, dorsal; C, left (major) chela, lateral; D, same, mesial; E, right (minor) chela, lateral; F, same, mesial; G, second pereiopod, lateral. Photographs by the author.

FIGURE 13. Alpheus shukran sp. nov., male (cl 11.0 mm) from Bandar Khayran, Oman (FLMNH UF 68873) [A–C]; ovigerous female (cl 13.2 mm) from the same locality (FLMNH UF 68870) [D–G]; A, shrimp alive, dorsal; B, same, lateral; C, frontal region, dorsal; D, shrimp alive, dorsal; E, same, lateral; F, carapace, frontal appendages and chelipeds, dorsal; G, frontal region, dorsal. Photographs by the author.

FIGURE 14. Alpheus shukran sp. nov., female (cl 12.7 mm) from Thuwal, Saudi Arabia (RSRC) [A–E]; aquarium-kept specimens (cl indet.) from Eilat, Israel [F, G]; male (cl 11.0 mm) from Bandar Khayran, Oman (FLMNH UF 68873) [H]; A, shrimp alive, dorsal; B, same, lateral; C, frontal region, dorsal; D, left (major) chela, mesial; E, right (minor) chela, mesial; F, shrimp alive, dorsal; G, shrimp in aquarium together with Cryptocentrus lutheri Klausewitz; H, male second pleopod, appendices masculina and interna, anterior. Photographs by the author [A–E] and Ilan Karplus [F, G, latter also published in Karplus et al. (1972a)].

FIGURE 15. Alpheus macellarius Chace, 1988, 1 male (cl 14.5 mm) from Raffles Lighthouse, Singapore (OUMNH.ZC.2014- 11-081); A, shrimp alive, dorsal; B, same lateral; C, frontal region, dorsal; D, tail fan, dorsal. Photographs by the author.

FIGURE 16. Alpheus macellarius Chace, 1988, female (cl 5.5 mm) from Nosy-Bé, Madagascar (FLMNH UF 14035) [A, B]; A, shrimp alive, dorsal; B, same, lateral. Alpheus cf. macellarius Chace, 1988, specimens from different western Pacific localities [C–H]; C, specimen (sex and cl indet.) from Koumac, New Caledonia (MNHN-IU-2018-778), shrimp alive, dorsal; B, same, lateral; E, female (cl 8.9 mm) from Madang, Papua New Guinea (MNHN-IU-2014-6031), shrimp alive, dorsal; F, same, lateral; G, ovigerous female (cl 10.2 mm) from Guam, Northern Mariana Islands (FLMNH UF 37357), shrimp alive, dorsal; H, same, lateral. Photographs by the author.

FIGURE 17. Alpheus macellarius Chace, 1988, in situ photographs; A, shrimp near burrow entrance, together with Cryptocentrus sp., Bali, Indonesia; B, shrimp and goby, Cryptocentrus caeruleomaculatus (Herre), outside of burrow, Bali, Indonesia; C, shrimp near its burrow among algae, partly exposed tide flat, Pulau Sekudu, Singapore; D, shrimp near burrow entrance, together with Cryptocentrus maudae Fowler, Sentosa, Singapore; E, F, shrimp (with bopyrid parasite) outside of burrow, together with Cryptocentrus cf. strigilliceps (Jordan & Seale), Watamu, Kenya. All identifications of shrimps and gobies tentative. Photographs courtesy of Andrey Ryanskiy (A, B), Marcus Ng (C, D), and Dawn Goebbels (E, F).

FIGURE 18. Alpheus tigrinus sp. nov., holotype, male (cl 15.3 mm) from Farasan Islands (Zahrat Durakah), Saudi Arabia (FLMNH UF 37012); A, frontal region, dorsal; B, same, lateral; C, telson, dorsal; D, tooth on ventromesial carina of first article of antennular peduncle, lateral; E, third maxilliped, lateral; F, second pereiopod, lateral; G, third pereiopod, lateral; H, same, propodus and dactylus, lateral; I, same, dactylus, ventromesial; J, fifth pereiopod, lateral; K, same, propodus and dactylus, mesial; L, male second pleopod, appendices masculina and interna, anterior; M, uropod, dorsal.

FIGURE 19. Alpheus tigrinus sp. nov., holotype, male (cl 15.3 mm) from Farasan Islands (Zahrat Durakah), Saudi Arabia (FLMNH UF 37012) [A–G]; paratype, male (cl 14.5 mm) from Farasan Islands (Abulad), Saudi Arabia (FLMNH UF 36905) [H, I]; paratype, ovigerous female (cl 16.7 mm) from Farasan Islands (Tiger Head Island), Saudi Arabia (FLMNH UF 36648) [J]; A, left (major) cheliped, ischium to proximal portion of chela, mesial; B, same, carpus and chela, lateral; C, same as B, mesial; D, same, dactylus, lateral; E, right (minor) cheliped, mesial; F, same, ischium to proximal portion of propodus (chela palm), lateral; G, same, carpus and chela, lateral; H, right (major) chela, lateral (setae omitted); I, left (minor) chela, lateral (setae omitted except for balaeniceps setae); J, right (minor) chela, lateral (setae omitted, balaeniceps setae absent).

FIGURE 20. Alpheus tigrinus sp. nov., female (cl 15.0 mm) from Port Sudan, Sudan (RMNH.CRUS.D.14302); A, habitus, lateral; B, frontal region, dorsal; C, same, lateral; D, right (major) chela, lateral; E, same, mesial; F, left (minor) cheliped, lateral; G, same as in F, different angle, lateral; H, same, mesial. Refer to A for scale.

FIGURE 21. Alpheus tigrinus sp. nov., paratype, ovigerous female (cl 16.7 mm) from Farasan Islands (Tiger Head Island), Saudi Arabia (FLMNH UF 36648); A, shrimp alive, dorsal; B, same, lateral. Photographs by the author.

FIGURE 22. Alpheus tigrinus sp. nov., paratype, male (cl 13.0 mm) from Farasan Islands (Tiger Head Island), Saudi Arabia (FLMNH UF 36957) [A]; holotype, male (cl 15.3 mm) from Farasan Islands (Zahrat Durakah), Saudi Arabia (FLMNH UF 37012) [B]; A, shrimp alive, dorsal; B, shrimp post-mortem (carapace damaged during collection), dorsal. Photographs by the author.

FIGURE 23. Alpheus tigrinus sp. nov., paratype, ovigerous female (cl 16.7 mm) from Farasan Islands (Tiger Head Island), Saudi Arabia (FLMNH UF 36648) [A, B]; holotype, male (cl 15.3 mm) from Farasan Islands (Zahrat Durakah), Saudi Arabia (FLMNH UF 37012) [C]; paratype, male (cl 13.0 mm) from Farasan Islands (Tiger Head Island), Saudi Arabia (FLMNH UF 36957) [D]; male (cl 15.4 mm) from Farasan Islands (Zahrat Durakah), Saudi Arabia (FLMNH UF 37015); A, frontal region, dorsal; B, tail fan, dorsal; C, frontal region and chelipeds, dorsolateral; D, frontal region, dorsal; E, left (major) cheliped, mesial. Photographs by the author.

FIGURE 24. Alpheus tigrinus sp. nov., ovigerous female (cl 14.3 mm) from Thuwal, Saudi Arabia (RSRC) [A–D]; young female (cl indet., released) from Rabigh, Saudi Arabia [E]; A, shrimp alive, dorsal; B, same, lateral; C, frontal region, dorsal; D, tail fan, dorsal; E, shrimp alive, dorsal. Alpheus aff. tigrinus, female (cl 6.5 mm) from St. John’s Island, Singapore (OUMNH. ZC.2014-11-082) [F, G]; F, shrimp alive, dorsal; G. same, lateral. Photographs by the author.

FIGURE 25. Alpheus cf. tigrinus [A–C] and Alpheus aff. tigrinus [D–H], mostly in situ photographs (except A); A, male (cl 14.3 mm) from Abu Dhabi, UAE (FLMNH UF 71625); B, shrimp near burrow entrance, together with Cryptocentrus lutheri Klausewitz, Kubbar Island, Kuwait; C, shrimp at burrow entrance, together with C. lutheri, Qatar; D, E, G, different shrimps at burrow entrances, together with Cryptocentrus nigrocellatus (Yanagisawa), Philippines (C), Japan (D, G); F, shrimp outside of its burrow (goby not in frame), Japan; H, shrimp at burrow entrance (burrow made under massive coral), with Cryptocentrus albidorsus (Yanagisawa), Kenting, Taiwan. Identifications of gobies tentative. Photographs courtesy of FLMNH team [A], Najim Al-Misbah [B], Redha Al-Kallabi [C], Ülar Tikk [D], Tomonori Hirata [E], Shunzo [F], Tomoki Iida [G], Ming-Shiou Jeng [H].