Palaemon migratorius ( Heller, 1862 )

Tzomos, Theodoros & Koukouras, Athanasios, 2015, Redescription of Palaemon antennarius H. Milne Edwards, 1837 and Palaemon migratorius (Heller, 1862) (Crustacea, Decapoda, Palaemonidae) and description of two new species of the genus from the circum-Mediterranean area, Zootaxa 3905 (1), pp. 27-51 : 37-48

Palaemon migratorius ( Heller, 1862)

( Figure 6 )

Pelias migratorius Heller, 1862: 409 ; Plate 2, Fig. 35 (partim).

Anchistia migratoria Heller, 1863: 259 ; Plate 8, Fig. 20 (partim).

Palaemonetes varians — Heller, 1869: 157 (partim).— Pesta, 1913: 25 (partim). Not P. varians Leach, 1813 .

Palaemonetes antennarius — Holthuis, 1950: 10 (partim). Holthuis, 1952: 21 — De Grave & Fransen, 2011:336 (partim). Not P. antennarius H. Milne Edwards, 1837 .

Material examined. Lectotype (hereby designated): 1 ♀ (pocl 8.9 mm), NHMW 25559, Aegypten (stn 61), coll. Kotschy. Paralectotypes: 1 ♀ (pocl 7.8 mm), NHMW 7733, Aegypten (stn 61), coll. Kotschy.; 2 ♀♀ (1 ovig) (pocl 6.9–8.1 mm), NHM 1923.5.11.19–20, Aegypten (stn 61), coll. Kotschy;

Redescription. Max. pocl: ♀♀ 8.9 mm, ♀♀ ovig 8.1 mm.

Carapace glabrous. Rostrum ( Figure 6 A) short, wide, straight, with posterior ventral curve; approximately 0.6 times pocl, failing to reach the end of scaphocerite; armed with 5–6 dorsal teeth and 2 ventral teeth; posterior-most tooth situated behind orbit, second tooth situated above of orbital margin; distal portion with simple or bifid tip; single row of setae dorsally and double row of setae ventrally. Antennal tooth marginal and branchiostegal tooth originating just before anterior margin of carapace. Branchiostegal groove originating dorsal to branchiostegal tooth, trending posteriorly and finishing just in front of half carapace length, slightly lower than at its origin. Suborbital lobe subquadrate to rounded, pterygostomial angle rounded. Béc ocellaire globular, with slightly convex anterior margin, slightly hooked median process, pointing upwards at approximately 60°, dorsal surface concave. Eye well developed, with pigmented cornea; cornea slightly wider but shorter than stalk; ocellus present dorsomesially. Antennular peduncle extending to the base of scaphocerite tooth; basal segment 2 times as long as wide, slightly convex outer margin, stylocerite acute, reaching beyond middle of the segment; antero-lateral tooth slightly exceeding laminar portion, reaching middle of penultimate segment; inner ventro-mesial tooth present; ultimate segment 1.2 times as long as penultimate, their combined length being 0.8 times that of basal segment. Dorsal flagellum of antennula fused for 0.8 times of its length (13–14 segments fused, 4–5 free); more than distal half with 6 aesthetascs on each segment arranged in 2 rows of 3. Scaphocerite slender, laminar, 3.0 times as long as broad; outer margin straight terminating in tooth, falling short of distal margin of lamina; basal segment of antenna with large mesial tooth; antenna articulated to lateral margin of this segment. Flagellum of antenna almost equal to the body length.

Abdominal pleurae, furnished with plumose setae on ventral margin; posterior end of the fifth pleuron rounded ( Figure 6 B); sixth segment approximately 2.0 times length of fifth; lateral margin ending in tooth disto-ventrally; median lobe acute, with ventral submedian process.

Fourth thoracic sternite of females ( Figure 6 D) armed with a sharp tooth pointing anteriorly and two submedian lobes on its posterior ridge, fifth sternite unarmed and with more acute submedian lobes, each of sixth and seventh sternites with a low, rounded, median boss and partial transverse ridge, eighth sternite with low, transverse ridge; in ovigerous females eighth sternite with setose transverse ridge.

First and second abdominal sternites of females ( Figure 6 E) with a median spicule decreasing in acuteness; third and fourth with a median boss; the fifth with a longitudinal ridge, bifid posteriorly. Pre-anal carina unarmed.

Mandible without palp. Incisor process of mandible with 3 teeth on right mandible, the middle of which is the smallest, and 4 teeth on left mandible, the middle 2 being smaller than the outer ones; molar process with 5–6 teeth of varying sizes. Paragnaths covering about half the mandibles; alae formed by broad, transverse slightly bilobed, distal lobes, ventromedial lobes triangular. Corpus short, narrowly separated medially; base with two carinae. Epistome triangular with rounded anterior angle and strong anteromedial carina. Labrum narrow, rectangular. Maxillula with lower lacinia near oval, smaller and narrower than upper lacinia; upper lacinia provided with several distal cuspidate and stout setae, without plumose setae on its upper margin; palp bilobed; upper lobe naked, lower lobe broad with 1–2 median setiform processes. Maxilla endopod deeply cleft, ending in a number of plumose setae, 3–4 simple setae proximally on the upper margin of the coxal endite; palp well developed, broad and naked, except for a few plumose setae proximally on its outer margin; scaphognathite large, fringed with plumose setae; the lower lobe is broader than the upper. First maxilliped endites ( Figure 6 C) separated with their inner edges lying on a straight line; margins of both endites with dense plumose setae; basal endite bears a dense row of 30–40 plumose setae before margin; coxal endite with an interrupted row of 15–20 setae before margin; palp slender and slightly twisted without distal simple setae; exopod well developed, slender and furnished with plumose setae distally; caridean lobe well developed and broad; epipod large and bilobed. Second maxilliped with a broad rectangular ultimate segment; penultimate segment broadly triangular, with convex, semicircular upper margin; exopod well developed; well developed podobranch present. Third maxilliped pediform; ultimate segment 0.8 times length of penultimate; ischiomerus with strongly curved dorsal margin; exopod equal or longer than ischiomerus; epipodal plate subtriangular; well developed arthrobranch and a second, rudimentary arthrobranch present.

Well developed pleurobranchiae present on all thoracic legs.

First pereiopod reaching beyond end of scaphocerite by length of dactylus; ischium 1.5 times length of basis; merus 2.0 times length of ischium; carpus 1.3 times longer than merus; carpus 2 times length of chela, fingers slightly longer than palm, with tufts of setae; carpal-propodal brush well developed. Second pereiopod extending beyond scaphocerite by full length of chela; ischium 4.0 times length of basis; merus equal with ischium; carpus elongate, 1.5 length of merus; carpus 1.3 times length of chela, fingers approximately 0.7 length of palm and covered in stout setae.

Ambulatory pereiopods increase in length, third pereiopod being the shortest. Third pereiopod reaching tip of distolateral tooth of scaphocerite; ischium twice length of basis; merus 2.0 times length of ischium; carpus 0.5 length of merus; propodus 1.8 times length of carpus, ventral margin armed with 4–5 pairs of cuspidate setae; dactylus simple, about 0.4 length of propodus. Fourth pereiopod overreaching scaphocerite by half of dactylus; ischium 2.5 times length of basis; merus 2.2 times length of ischium and 2.3 times length of carpus; propodus 2.0 times length of carpus and approximately equal to merus, ventral margin provided with 5–6 pairs of cuspidate setae; propodus 2.7 length of dactylus. Fifth pereiopod overreaching scaphocerite by half of dactylus; ischium 2 times length of basis; merus 2.5 times length of ischium and 1.9 times length of carpus; propodus 1.9 times length of carpus and slightly longer than merus, ventral margin armed with 5–6 pairs of cuspidate setae, grooming brush with 6 rows of serrulate setae; propodus 3.3 length of dactylus.

First pleopod of females, lacking appendix interna; exopod is 3.0 times length of endopod; endopod with concave inner margin and a rounded tip. Second to fifth pleopods similar with the endopod being slightly shorter than the exopod, bearing an appendix interna.

Telson subequal in length to sixth pleonite; length:width ratio 3.0:1 proximally narrowing to 6.0:1 distally; dorsal surface with 2 pairs of dorsal spines situated dorsomedially and 1 pair of simple setae subdistally on median process; proximal pair of spines situated at about 0.5 of telson length, distal pair at about 0.7 length; marginal lanceolate setae absent; posterior margin ( Figure 6 F) prolonged into acute process, with 4–7 plumose setae and 2 pairs spines; inner pair of spines subequal with plumose setae and 2.5 times longer than outer pair; median process exceeding outer pair of spines.

Uropods broadly ovate; endopod overreaching telson by its distal margin; exopod slightly longer than endopod; mobile lateral spine of exopod overreaching fixed tooth by length of tip.

Eggs numerous; 0.75 x 1.25 mm.

Distribution. Egypt ( Figure 1 ).

Remarks. Palaemon migratorius was reported from Egypt, Garda Lake ( Italy) and Adriatic Sea as Pelias migratorius by Heller (1862). The type material of the species that Heller (1862) examined, was deposited in NMW, part of which was collected by Kotchy. The labels of NMW vials verify that Heller was the determinator and Kotchy the collector of the Egyptian samples. In 1863, Heller transferred P. migratorius to the genus Anchistia giving an updated description. Heller’s descriptions ( Heller, 1862; 1863) match the material he examined, except from the form of the telson distal part, which in the study of 1862 bears 3 long movable spines, while in the one of 1863 bears 3 long and 3 short movable spines. Later, in 1869, the same author placed the species as synonym of Palaemonetes varians (cf. Heller, 1869) and specifically states that Kotchy collected the Egyptian sample.

Pesta (1913), in his study on P. mesopotamicus , questions the presence of P. varians in Egypt. On the other hand, the distribution of P. migratorius according to Heller (1862, 1863, 1869), obviously includes part of P. antennarius distribution. This confusion and most probably the overlapping distributions led Holthuis (1950) to place Pelias migratorius as junior synonym of P. antennarius .

In the present study the specimens examined from Egypt are those studied by Heller (1862) and Pesta (1913), collected by Kotschy. Although, neither Heller’s and Pesta’s studies nor the vial labels provide specific sampling information, the examination of Kotschy’s material revealed that P. migratorius should be considered as a valid species (see below). For this resurrected species, only Egypt should be referred as the type locality excluding Garda Lake ( Italy) and Adriatic Sea.

Palaemon migratorius can be easily separated from P. antennarius , P. colossus sp. nov., P. mesogenitor , P. turcorum , P. v ar i a ns and P. z ar i q ui ey i by the rounded end of the fifth pleuron (vs. pointed or subquadrate; Figures 6 B vs. 2E, 7B, 10A in present study; 6b in Holthuis, 1961). Furthermore, P. migratorius bears 4–7 setae on the telson distal part and thus can be separated from P. mesopotamicus and P. minos sp. nov. that have 10–12 and 2 respectively ( Figures 6 F vs. 9C, 10D).

Regarding first maxilliped endites, in P. migratorius , the two endites are arranged almost in a straight line forming just a notch between them, while in P. antennarius , P, colossus sp. nov. and P. minos sp. nov. the endites form an obtuse angle mesially ( Figures 6 C vs. 3F). In respect of third maxilliped, in P. migratorius the exopod is equal or longer than ischiomerus, while in P. mesopotamicus the exopod is clearly shorter ( Figure 10 G).

Finally, since no male specimens were available, the distinction of this species is based only on female specimens.

Palaemon colossus sp. nov. ( Figures 7 , 8 )

Palaemonetes antennarius — Holthuis, 1961: 14; Fig. 5 (Not P. antennarius H. Milne Edwards, 1837 ). Palaemonetes n. sp. 2—Tzomos et al. 2010: 39.

Material examined. Holotype: 1 ♀ (pocl 8.5 mm), OUMNH.ZC.2014–13–001, Epta piges, Rhodes Island, Greece (stn 56), 10.4.2010, coll. Anastasiadou Ch.; Paratypes: 2 ♀♀ (pocl 7.0–8.0 mm), 1 ♂ (pocl 6.5 mm), OUMNH.ZC.2014–13–002, Epta piges, Rhodes Island, Greece (stn 56), 10.4.2010, coll. Anastasiadou Ch.; 1 ♀ (pocl 6.4 mm), 1 ♂ (pocl 6.6 mm), NHM.2015.582–583, Epta piges, Rhodes Island, Greece (stn 56), 10.4.2010, coll. Anastasiadou Ch.;

Non-type material. Greece: 98 ♀♀ (8 ovig) (pocl 5.0–12.0 mm), 66 ♂♂ (pocl 4.5–8.5 mm), ZMAUTH–G3–30, Epta piges, Rhodes Island (stn 56), 2002, coll. Anastasiadou Ch.; Turkey: 2 ♀♀ (pocl 6.5–7.1 mm), 1 ♂ (pocl 5.2 mm), OUMNH.ZC. 2007–16 –002, Olympos Valley (stn 57), 27.3.2007, coll. Schubart C.D. & S. Reuschel; 15 ♀♀ (5 ovig) (pocl 7.0–10.0 mm), 5 ♂♂ (pocl 5.0– 7.2 mm), SMF, Burdur, Antalya (stn 58), 2002; 5 ♀♀ (pocl 6.0– 7.6 mm), 2 ♂♂ (pocl 5.0– 5.9 mm), OUMNH.ZC.2002–02–001, Antalya, Ihaniyie, Anatolia (stn 59), 13.5.2001, coll. Mann D.

Description. Max. pocl: ♂♂ 8.5 mm, ♀♀ 11 mm, ♀♀ ovig 12 mm.

Carapace glabrous. Rostrum ( Figure 7 A) wide, straight, with posterior ventral curve; approximately 0.8 times pocl, reaching just before or at the end of scaphocerite; armed with 4–6 dorsal teeth and 1–2 ventral teeth; posterior-most tooth situated behind or above orbit, second tooth situated in front of orbital margin; distal portion with simple (in the 70% of the examined individuals) or bifid (in the 30%) tip; single row of setae dorsally and double row of setae ventrally. Antennal tooth marginal and branchiostegal tooth originating just before anterior margin of carapace. Branchiostegal groove originating dorsal to branchiostegal tooth, trending posteriorly and finishing just in front of half carapace length, slightly lower than at its origin. Sub-orbital lobe subquadrate to rounded, pterygostomial angle rounded. Béc ocellaire globular, with convex anterior margin, slightly hooked median process, pointing upwards at approximately 60°, dorsal surface with strong concavity. Eye well developed, with pigmented cornea; cornea slightly wider but shorter than stalk; ocellus present dorsomesially. Antennular peduncle extending to the base of scaphocerite tooth in females and just before the tip of scaphocerite tooth in males; basal segment 2.0 times as long as wide, slightly convex outer margin, stylocerite acute, reaching beyond middle of the segment; antero-lateral tooth slightly exceeding laminar portion, reaching middle of penultimate segment; inner ventro-mesial tooth present; ultimate segment 1.2 times as long as penultimate, their combined length being 0.8 times that of basal segment. Dorsal flagellum of antennula fused for 0.8 times of its length (11–15 segments fused, 4–6 free); more than distal half with 6 aesthetascs on each segment arranged in 2 rows of 3. Scaphocerite slender, laminar, 2.5–3.0 times as long as broad; outer margin straight terminating in tooth, falling short of distal margin of lamina; basal segment of antenna with large mesial tooth; antenna articulated to lateral margin of this segment. Flagellum of antenna almost equal to the body length.

Abdominal pleurae, except first, furnished with plumose setae on ventral margin; posterior and ventral margins of fifth pleuron ( Figures 7 B) forming an 80° angle and a slightly pointed posterodistal end; sixth segment approximately 1.8 times length of fifth; lateral margin ending in tooth disto-ventrally; median lobe acute, with ventral submedian process.

Thoracic sternal armature sexually dimorphic ( Figure 7 D). Fourth thoracic sternite of females armed with a stout, slightly hooked, sharp tooth, pointing rather posteriorly and two low, median lobes on its posterior ridge, fifth sternite with more acute median lobes on its posterior ridge, sixth to seventh thoracic sternites with low, rounded median bosses and partial transverse ridges, eighth with well developed, transverse ridge; in ovigerous females eighth sternite with setose transverse ridge. Eighth thoracic sternite in males with a developed, transverse ridge, projected anteriorly forming the greek capital letter Lambda (Λ).

Abdominal sternal armature sexually dimorphic ( Figure 7 E). In females, first to third abdominal sternites with transverse ridges slightly lifted medially, fourth with median boss and fifth with a longitudinal ridge, bifid posteriorly. In males, first to third abdominal sternites bearing acute conical tooth; fourth to fifth abdominal sternites as in females. Pre-anal carina unarmed in both sexes.

Mandible without palp. Incisor process of mandible with 3 teeth on right mandible, the middle of which is the smallest, and 4 teeth on left mandible, the middle 2 being smaller than the outer ones; molar process with 5–6 teeth of varying sizes. Paragnaths covering about half the mandibles; alae formed by broad, transverse slightly bilobed, distal lobes, ventromedial lobes triangular. Corpus short, narrowly separated medially; base with two carinae. Epistome triangular with rounded anterior angle and strong anteromedial carina. Labrum narrow, rectangular. Maxillula ( Figure 7 C) with lower lacinia near oval, smaller and narrower than upper lacinia; upper lacinia provided with several distal cuspidate and stout setae, with 3–4 plumose setae on its upper margin; palp deeply bilobed; upper lobe narrow and naked, lower lobe broad with 1–3 median setiform processes. Maxilla endopod deeply cleft, ending in a number of plumose setae, 3–4 simple setae proximally on the upper margin of the lower endite; palp well developed, broad and naked, except for a few plumose setae proximally on its outer margin; scaphognathite large, fringed with plumose setae; the lower lobe is broader than the upper. First maxilliped endites separated with their inner edges forming an obtuse angle; margins of both endites with dense plumose setae; basal endite bears a row of 13–15 plumose setae before margin; coxal endite with 5 simple setae before margin; palp slender and slightly twisted with 1–2 distal simple setae; exopod well developed, slender and furnished with plumose setae distally; caridean lobe well developed and broad; epipod large and bilobed. Second maxilliped with a broad rectangular ultimate segment; penultimate segment broadly triangular, with convex, semicircular upper margin; exopod well developed; well developed podobranch present. Third maxilliped pediform; ultimate segment 0.9 times length of penultimate; ischiomerus with strongly curved dorsal margin; exopod equal or slightly shorter than ischiomerus; epipodal plate subtriangular; well developed arthrobranch and a second, rudimentary arthrobranch present.

Well developed pleurobranchiae present on all thoracic legs.

First pereiopod reaching before end of scaphocerite; ischium 1.4 times length of basis; merus 1.8 length of ischium; carpus 1.2 times longer than merus; carpus 2.0 times length of chela, fingers equal with palm, with tufts of setae; carpal-propodal brush well developed. Second pereiopod extending beyond scaphocerite by full length of chela; ischium 4.0 times length of basis; merus equal with ischium; carpus elongate, 1.4 length of merus; carpus 1.2 times length of chela, fingers 0.75 length of palm and covered in stout setae.

Ambulatory pereiopods increase in length, third pereiopod being shortest. Third pereiopod reaching tip of distolateral tooth of scaphocerite; ischium twice length of basis; merus 2.4 times length of ischium; carpus 0.5 length of merus; propodus 2.0 times length of carpus, ventral margin armed with 4–6 pairs of cuspidate setae; dactylus simple, about 0.4 length of propodus. Fourth pereiopod reaching end of scaphocerite; ischium 2.5 times length of basis; merus 2.5 times length of ischium and 2.3 times length of carpus; propodus 2.3 times length of carpus and approximately equal to merus, ventral margin provided with 5 pairs of cuspidate setae; propodus 3 times length of dactylus. Fifth pereiopod reaching end of scaphocerite; ischium 2 times length of basis; merus 2.5 times length of ischium and 2 times length of carpus; propodus 2.3 times length of carpus and slightly longer than merus, ventral margin armed with 5 pairs of cuspidate setae, grooming brush with 7 rows of serrulate setae at the proximal end of propodus; propodus 3.3 length of dactylus.

First pleopod sexually dimorphic in proportions, lacking appendix interna in both sexes; in males ( Figure 8 A), exopod is 1.6 times length of endopod; endopod deeply concave on the mesial portion of inner margin; both exo- and endopod fringed with plumose setae but mesial portion of the inner margin of endopod devoid of plumose setae, with 7–12 spiniform setae; in females ( Figure 8 B), exopod is 2.7 times length of endopod; endopod with concave inner margin and rounded tip. Second to fifth pleopods similar with endopod being slightly shorter than exopod, bearing an appendix interna. Second pleopod of males with appendix masculina; about 2 times length of appendix interna, furnished with 7–10 lateral and 3–4 apical setae.

Telson ( Figure 8 C) subequal in length to sixth pleonite; length:width ratio 3.3:1 proximally, narrowing to 7.5:1 distally; dorsal surface with 2 pairs of dorsal spines situated dorsomedially and 2 pairs of simple setae subdistally on median process; proximal pair of spines situated at about 0.6 of telson length, distal pair at about 0.8 length; 40–50 pairs of marginal lanceolate setae ( Figure 8 D) present throughout the length; posterior margin prolonged into acute process, with 1 pair of plumose setae and 2 pairs spines; inner pair of spines subequal with plumose setae and about 2.5–3.0 times longer than outer pair; median process exceeding outer pair of spines.

Uropods broadly ovate; endopod overreaching telson by its distal margin; exopod slightly longer than endopod; mobile lateral spine of exopod overreaching fixed tooth by length of tip.

Eggs numerous; 1.3 x 1.7 mm.

Distribution. Rhodes Island, Greece; Antalya region, Turkey ( Figure 1 ).

Etymology. The Colossus of Rhodes was a statue dedicated to the greek god Helios and was erected in Rhodes Island. The name is used as a noun in apposition.

Remarks. Palaemon colossus sp. nov. appears to be morphologically most similar to P. antennarius sharing among others, main key characters as the shape of the distal end of fifth pleuron and the form of the distal part of telson. This similarity was most probably the reason for the assignment of populations from Rhodes Island and the adjacent Turkey as P. antennarius by Holthuis (1961). However, P. colossus sp. nov. has 40–50 pairs of lanceolate setae along the ventral margins of telson while, P. antennarius has 0–6 pairs just in the proximal part ( Figures 8 C, 8D vs. 5A). Additionally, the two species differ also by the shape of the endopod of first pleopopod in males and females ( Figures 8 A, 8B vs. 4F, 4H) and by the form of the abdominal sternal armature in both sexes ( Figures 7 E vs. 3B). Finally, P. colossus sp. nov. from Rhodes can be seperated by the deeply bilobed maxillula palp and the presence of 2–3 setiform processes on its lower lobe whereas in P. antennarius the palp is more shallowly bilobed and bears just 1 process ( Figures 7 C vs. 3D). Specimens of Palaemon colossus sp. nov. from Antalya region have just 1 setiform process on maxillula palp instead of 2–3 in the specimens from Rhodes, but maintain a deeply bilobed palp. Nevertheless, the setation of the ventral margins of telson, the shape of the endopod of first pleopopod and the form of the abdominal sternal armature remain stable and can be used for the safe distinction from P. antennarius .

Among the other species from the study area, P. colossus sp. nov. could be distinguished using key characters common with P. antennarius .

Palaemon minos sp. nov. ( Figure 9 )

Palaemonetes antennarius — Holthuis, 1961: 14. Not P. antennarius H. Milne Edwards, 1837 . Palaemonetes n. sp. 1—Tzomos et al. 2010: 39.

Material examined. Holotype: 1 ♂ (pocl 4.5 mm), OUMNH.ZC.2014–13–003, Kourna Lake, Crete, Greece (stn 55), 10.8.2007, coll. Tzomos Th.; Paratypes: 2 ♀♀ (1 ovig) (pocl 7.0–8.0 mm), 1 ♂ (pocl 5.0 mm), OUMNH.ZC.2014–13–004, Kourna Lake, Crete, Greece (stn 55), 10.8.2007, coll. Tzomos Th.

Non-type material. Greece: 114 ♀♀ (pocl 4.0–8.0 mm), 142 ♂♂ (pocl 4.0–7.0 mm), ZMAUTH–G3–31, Kourna Lake, Crete, Greece (stn 55), 2001, coll. Anastasiadou Ch.

Description. Max. pocl: ♂♂ 7 mm, ♀♀ 8 mm, ♀♀ ovig 8 mm.

Carapace glabrous. Rostrum ( Figure 9 A) wide, straight or slightly pointed upwards, with posterior ventral curve; approximately 0.8 times pocl, reaching or not the end of scaphocerite; armed with 6–7 dorsal teeth and 2–4 ventral teeth; posterior-most tooth situated behind orbit, second tooth situated above of orbital margin; distal portion with simple tip; single row of setae dorsally and double row of setae ventrally. Antennal tooth marginal and branchiostegal tooth originating clearly before anterior margin of carapace. Branchiostegal groove originating dorsal to branchiostegal tooth, trending posteriorly and finishing just in front of half carapace length, slightly lower than at its origin. Sub-orbital lobe subquadrate to rounded, pterygostomial angle rounded. Béc ocellaire globular, with slightly convex anterior margin, slightly hooked median process, pointing upwards at approximately 75°, dorsal surface concave. Eye well developed, with pigmented cornea; cornea slightly wider but shorter than stalk; ocellus present dorsomesially. Antennular peduncle extending to base of scaphocerite tooth in females and just before tip of scaphocerite tooth in males; basal segment 2 times as long as wide, slightly convex outer margin, stylocerite acute, reaching beyond middle of segment; antero-lateral tooth slightly exceeding laminar portion, reaching middle of penultimate segment; inner ventro-mesial tooth present; ultimate segment 1.2 times as long as penultimate, their combined length being 0.8 times that of basal segment. Dorsal flagellum of antennula fused for 0.8 times of its length (9–13 segments fused, 3–5 free); more than distal half with 6 aesthetascs on each segment arranged in 2 rows of 3. Scaphocerite slender, laminar, 2.8–3.2 times as long as broad; outer margin straight terminating in tooth, falling short of distal margin of lamina; basal segment of antenna with large mesial tooth; antenna articulated to lateral margin of this segment. Flagellum of antenna almost equal to body length.

Abdominal pleurae, furnished with plumose setae on ventral margin; posterior end of the fifth pleuron rounded ( Figure 9 B); sixth segment approximately 2.0 times length of fifth; lateral margin ending in tooth disto-ventrally; median lobe acute, with ventral submedian process.

Thoracic sternal armature sexually dimorphic ( Figure 9 D). In females, fourth thoracic sternite armed with a sharp, slightly hooked tooth, pointing posteriorly and two submedian lobes on its posterior ridge, fifth sternite unarmed and with more acute submedian lobes, sixth sternite with a median boss and low submedian lobes, seventh sternite with low, rounded, median boss and partial transverse ridge, eighth sternite with low, transverse ridge; in ovigerous females eighth sternite with setose transverse ridge. In males fifth sternite with a spicule, sixth with a conical tooth, eighth thoracic sternite with a, low transverse ridge, projected anteriorly forming the greek capital letter Lambda (Λ).

Abdominal sternal armature sexually dimorphic ( Figure 9 E). First to fourth abdominal sternites of female with a median spicule decreasing in acuteness; the fifth with a longitudinal ridge, bifid posteriorly. In males, first to third abdominal sternites bearing acute conical tooth decreasing in height, fourth with an acute conical tooth higher than that of third, fifth abdominal sternite as in females. Pre-anal carina unarmed in both sexes.

Mandible without palp. Incisor process of mandible with 3 teeth on right mandible, the middle of which is the smallest, and 4 teeth on left mandible, the middle 2 being smaller than the outer ones; molar process with 5–6 teeth of varying sizes. Paragnaths covering about half the mandibles; alae formed by broad, transverse slightly bilobed, distal lobes, ventromedial lobes triangular. Corpus short, narrowly separated medially; base with two carinae. Epistome triangular with rounded anterior angle and strong anteromedial carina. Labrum narrow, rectangular. Maxillula with lower lacinia near oval, smaller and narrower than upper lacinia; upper lacinia provided with several distal cuspidate and stout setae, without plumose setae on its upper margin; palp bilobed; upper lobe naked, lower lobe broad with 1 median setiform process. Maxilla endopod deeply cleft, ending in a number of plumose setae, 3–4 simple setae proximally on the upper margin of the lower endite; palp well developed, broad and naked, except for a few plumose setae proximally on its outer margin; scaphognathite large, fringed with plumose setae; the lower lobe is broader than the upper. First maxilliped endites separated with their inner edges forming an obtuse angle; margins of both endites with dense plumose setae; basal endite bears a row of 12–14 plumose setae before margin; coxal endite without setae before margin; palp slender and slightly twisted with 1 distal simple seta; exopod well developed, slender and furnished with plumose setae distally; caridean lobe well developed and broad; epipod large and bilobed. Second maxilliped with a broad rectangular ultimate segment; penultimate segment broadly triangular, with convex, semicircular upper margin; exopod well developed; well developed podobranch present. Third maxilliped pediform; ultimate segment 0.9 times length of penultimate; ischiomerus with strongly curved dorsal margin; exopod equal with ischiomerus; epipodal plate subtriangular; well developed arthrobranch and a second, rudimentary arthrobranch present.

Well developed pleurobranchiae present on all thoracic legs.

First pereiopod reaching scaphocerite; ischium 1.4 times length of basis; merus 1.9 length of ischium; carpus 1.3 times longer than merus; carpus 2.0 times length of chela, fingers slightly longer than palm, with tufts of setae; carpal-propodal brush well developed. Second pereiopod extending beyond scaphocerite by full length of chela; ischium 4.0 times length of basis; merus equal with ischium; carpus elongate, 1.4 length of merus; carpus 1.3 times length of chela, fingers approximately 0.7 length of palm and covered in stout setae.

Ambulatory pereiopods increase in length, third pereiopod being the shortest. Third pereiopod reaching base of distolateral tooth of scaphocerite; ischium twice length of basis; merus 2.0 times length of ischium; carpus 0.5 length of merus; propodus 1.7 times length of carpus, ventral margin armed with 4–5 pairs of cuspidate setae; dactylus simple, about 0.4 length of propodus. Fourth pereiopod overreaching scaphocerite by full length of dactylus; ischium 2.5 times length of basis; merus 2.2 times length of ischium and 2.3 times length of carpus; propodus 2.0 times length of carpus and approximately equal to merus, ventral margin provided with 5–6 pairs of cuspidate setae; propodus 2.7 length of dactylus. Fifth pereiopod overreaching scaphocerite by full length of dactylus; ischium 2.0 times length of basis; merus 2.5 times length of ischium and 2.1 times length of carpus; propodus 2.2 times length of carpus and slightly longer than merus, ventral margin armed with 5 pairs of cuspidate setae, grooming brush with 6 rows of serrulate setae; propodus 3.3 length of dactylus.

First pleopod sexually dimorphic in proportions, lacking appendix interna in both sexes; in males exopod is 1.5–1.6 times length of endopod; endopod slightly concave on the mesial portion of inner margin; both exo- and endopods fringed with plumose setae but mesial portion of inner margin of endopod devoid of plumose setae, with 9–11 spiniform setae; in females, exopod is 3.0 times length of endopod; endopod lanceolate. Second to fifth pleopods similar with endopod being slightly shorter than exopod, bearing an appendix interna. Second pleopod of males with appendix masculina; about 1.5 times length of appendix interna, furnished with 14–17 lateral and 3–4 apical setae.

Telson subequal in length to sixth pleonite; length:width ratio 3.5:1 proximally narrowing to 7.0:1 distally; dorsal surface with 2 pairs of dorsal spines situated dorsomedially and 2 pairs of simple setae subdistally on median process; proximal pair of spines situated at about 0.5 of telson length, distal pair at about 0.7 length; marginal lanceolate setae absent; posterior margin ( Figure 9 C) prolonged into acute process, with 1 pair of plumose setae and 2 pairs spines; inner pair of spines shorter than plumose setae and 2.8–3.5 times longer than outer pair; median process exceeding outer pair of spines.

Uropods broadly ovate; endopod overreaching telson by its distal margin; exopod slightly longer than endopod; mobile lateral spine of exopod overreaching fixed tooth by length of tip.

Eggs numerous; 0.9 x 1.2 mm.

Distribution. Kourna lake, Crete Island, Greece ( Figure 1 ).

Etymology. In greek mythology, Minos was a king of Crete, son of Zeus and Europa. The name is used as a noun in apposition.

Remarks. As in the case of Palaemon colossus sp. nov., the population of P. minos sp. nov. from Crete Island was placed under P. antennarius ( Holthuis, 1961) . Nevertheless, P. minos sp. nov. presents obvious differences from P. antennarius . The fifth pleuron end of P. minos sp. nov. is rounded and not pointed as in P. antennarius ( Figures 9 B vs. 2E) and the plumose setae always overreach the inner spines of the telson distal part contrary to P.

antennarius where the setae are shorter or equal with the inner spines ( Figures 9 C vs. 5B). Aditionally, the two species differ also by the form of the thoracic and abdominal sternal armatures ( Figures 9 D, 9E vs. 3A, 3B).

The rounded end of the fifth pleuron is a key character that can be used for the separation of P. minos sp. nov. from all the other species of the study area except P. mesopotamicus and P. migratorius ( Figures 9 B vs. 7B, 10A). However, P. mesopotamicus and P. migratorius have 10–12 and 4–7 setae on the telson distal part respectively, whereas P. minos sp. nov. bears only 2 ( Figures 9 C vs. 6F, 10D).

Comparative material examined. Palaemon mesogenitor : Algeria: 4 ♀♀ (pocl 4.0– 4.2 mm), 1 ♂ (pocl 4.0 mm), NHM 1906.1.26.1–7, Oumach, South-West of Biskra (stn 16), 16– 18.1.1906; 1 ♀ (pocl 5.2 mm), 6 ♂♂ (pocl 4.2–5.1 mm), NHM 1949.10.2.1–2, NHM 1950.1.2.81, NHM 1950.1.2.82–83, Source D’ Oumach (stn 16), 23.2.1906, coll. Gurney R. Tunisia: 1 ♀ (pocl 4.3 mm), 1 ♂ (pocl 4.0 mm), SMF –12420, Djerid - Tozeur Oasis (stn 17), 27.12.1980, coll. Damian H.; 1 ♀ (pocl 5.0 mm), 1 ♂ (pocl 4.6 mm), Bou Chenini, Gabes (stn 18); 3 ♀♀ (pocl 8.5–9.1 mm), 4 ♂♂ (pocl 4.8–5.2 mm), NHM 1948.6.30.1–4, NHM 1948.6.30.5–9, Teboulbou, Southern Tunisia (stn 18), 2.4.1925, coll. Omer Cooper J.; 10 ♀♀ (pocl 4.7–9.4 mm), 6 ♂♂ (pocl 4.0– 5.5 mm), NHM 1924.2.26.1–10, Oasis of Gabes (stn 18), coll. Harkness D.A.; 30 ♀♀ (11 ovig) (pocl 6.2–9.5 mm), NHM 1925.11.6.1–15, Southern Tunisia (stn 19), 26/ 31.3.1925, coll. Omer Cooper J.

Palaemon mesopotamicus : Syria: 40 ♀♀ (pocl 4.0–7.0 mm), 40 ♂♂ (pocl 4.0– 5.2 mm), SMF –TSH 19/88, 21/88, 23/88, 26/88, 28/88, 30/88, Khabur river (stn 60), 5– 9.10.1988; 1 ♀ (pocl 6.2 mm), 1 ♂ (pocl 5.0 mm), NHM 1923.5.11.1–2, Hsitsch am Chabur (stn 60), 19.6.1910, coll. Pietschmann V.

Palaemon turcorum : Turkey: 3 ♀♀ (pocl 5.9–7.8 mm), 2 ♂♂ (pocl 4.5–5.8 mm), RMNH D 13971, Sakarya river, southwest of Ankara (stn 54), 18.6.1959, coll. Swennen C.

Palaemon varians : Germany: 32 ♀♀ (pocl 5.5–8.6 mm), 10 ♂♂ (pocl 4.9–7.9 mm), Jade river, Varel (stn 1); Belgium: 1 ♀ (pocl 9.0 mm), 1 ♂ (pocl 6.0 mm), OUMNH.ZC. 2004–07 –008, Spaarbekken, Nieuwpoort (stn 2), 6.8.2004, coll. De Grave S.; United Kingdom: 2 ♀♀ (pocl 4.6–7.0 mm), 1 ♂ (pocl 4.0 mm), OUMNH.ZC. 2004–06 –006, Camber, Sussex (stn 3), 27.8.2004, coll. De Grave S.; 2 ♀♀ (pocl 7.5–8.0 mm), 2 ♂♂ (pocl 5.9–6.8 mm), OUMNH.ZC. 2002–19 –002, Warham salt marsh, East of Wells, Horsey, Norfolk (stn 4), 6.7.2002, coll. Holland Z.; 2 ♀♀ (pocl 5.0– 7.8 mm), NHM 1949.12.12.1–2, Horshey (stn 4), 23.4.1906, coll. Gurney R.; 5 ♀♀ (2 ovig) (pocl 5.5–11.0 mm), 1 ♂ (pocl 7.1 mm), NHM 1911.11.8.2092–2096, Hartlepool (stn 5); 4 ♀♀ (3 ovig) (pocl 9.0–11.0 mm), 15 ♂♂ (pocl 6.5–8.0 mm), NHM 1958.8.1.1–5, Roose Cote, Barrow in Furness (stn 6), 24.6.1957; 112 ♀♀ (94 ovig) (pocl 7.3–11.0 mm), 2 ♂♂ (pocl 5.5–6.1 mm), NHM 1959.10.17.72–82, Roose Cote, Power Station, Morecambe Bay (stn 6), 24.6.1957; 1 ♀ (pocl 4.0 mm), NHM 1911.11.8.2111–2130, Dorset (stn 7), coll. Mc Waddington; 2 ♀♀ (pocl 6.7–8.2 mm), 1 ♂ (pocl 6.0 mm), OUMNH.ZC. 2003–21 –116, baie de Pulais, Guernsey, Channel Isles (stn 9), 19.5.2003, coll. De Grave S.; 3 ♀♀ (3 ovig) (pocl 8.0– 9.5 mm), 1 ♂ (pocl 6.1 mm), NHM 1911.11.8.2097–2102, Guernsey, Channel Isles (stn 9); Ireland: 1 ♀ (pocl 9.8 mm), 1 ♂ (pocl 5.0 mm), OUMNH.ZC. 2002–11 –001, Douglas Hall Lawn, saltmarsh, Cork harbour, Co. Cork (stn 8), 26.11.2001, coll. Whitaker A.; 1 ♀ (pocl 8.8 mm), 1 ♂ (pocl 5.8 mm), OUMNH.ZC.2004–02–001, Reenydonegan, Bantry Bay, Co. Cork (stn 8), 7.6.2002, coll. Oliver G.; 1 ♀ (pocl 7.9 mm), 1 ♂ (pocl 5.7 mm), OUMNH.ZC.2004–02–002, Rostellan, Cork Harbour, Co. Cork (stn 8), 29.7.2002, coll. Oliver G.; 1 ♀ (pocl 9.0 mm), 1 ♂ (pocl 7.2 mm), OUMNH.ZC.2004–02–003, Oysterhaven, Clashroe, Co. Cork (stn 8), 19.8.2002, coll. Oliver G.; France: 2 ♀♀ (1 ovig) (pocl 7.5–9.9 mm), 2 ♂♂ (pocl 6.5–7.1 mm), NHM 1911.11.8.2131–2134, Le Croisic (stn 10), 1906; 4 ♀♀ (2 ovig) (pocl 8.8–9.2 mm), 1 ♂ (pocl 5.5 mm), NHM 1981.262, NHM 1981.281, Noir moutier, Vendee (stn 11), 8.8.1955, coll. Bruce A.J.; Portugal: 2 ♀♀ (pocl 6.5–8.0 mm), 1 ♂ (pocl 4.2 mm), OUMNH.ZC. 2003–13 –018, Salgados lagoon (stn 12), 8.4.2003, coll. McGrath D.; Spain: 3 ♀♀ (pocl 6.1–8.0 mm) mm), 1 ♂ (pocl 5.4 mm), NHM 1954.12.30.85–89, Puerto Santa Maria, Cadiz (stn 13), 8.1950, coll. Zariquiey R.; Morocco: 1 ♂ (pocl 5.0 mm), Moulouya river (stn 14), 11.4.2011, coll. Melhaoui M.; Algeria: 18 ♀♀ (pocl 6.0– 9.8 mm), NHM 1923.1.30.1–4, NHM 1925.3.7.1–5, NHM 1928.10.15.61–63, Lake Fetzara (stn 15), 12.1922, coll. Chevreux E.

Palaemon zariquieyi : Spain: 76 ♀♀ (11 ovig) (pocl 6.0–10.0 mm), 27 ♂♂ 4.5–8.1, Albufera Lagoon, Valencia (stn 20); 1 ♀ (pocl 7.0 mm), 1 ♂ (pocl 4.5 mm), OUMNH.ZC. 2004–11 –001, Las Turberas, Prat de Cabamas, Torreblanca (stn 21), 10.2.2001, coll. Herrando-Perez S.

Figures

FIGURE 1. Map showing the sampling localities and the geographic distribution of the inland representatives of Palaemon in Europe, Middle East and North Africa. Numbers 1 – 61, indicate the different sampling stations. The symbols correspond to different Palaemon species.

FIGURE 5. Palaemon antennarius H. Milne Edwards, 1837. A. Telson. B. Telson distal part. Lectotype ♀ (pocl 7.7 mm), MNHN – IU – 2013 – 9296 (= MNHN – Na 1500), Trasimeno Lake, Italy. Scale bar indicates 3 mm (A), 1 mm (B).

FIGURE 6. Palaemon migratorius (Heller, 1862). A. Whole animal, lateral view. B. Fifth pleuron. C. First maxilliped. D. Thoracic sternal armature. E. Abdominal sternal armature. F. Telson distal part. A – B, D – F lectotype ♀ (pocl 8.9 mm), NHMW 25559, Egypt; C ♀ paralectotype (pocl 6.9 mm), NHMW 7733, Egypt. Scale bar indicates 2 mm (A), 1 mm (B, C), 1.5 mm (D, E), 0.5 mm (F).

FIGURE 7. Palaemon colossus sp. nov. A. Whole animal, lateral view. B. Fifth pleuron. C. Maxillula. D. Thoracic sternal armature. E. Abdominal sternal armature. A – B, D – E holotype ♀ (pocl 8.5 mm), OUMNH. ZC. 2014 – 13 – 001, Epta Piges, Rhodes Island, Greece; C, D – E, ♂ (pocl 6.0 mm), ZMAUTH – G 3 – 30, Epta Piges, Rhodes Island, Greece, 2002, coll. Anastasiadou Ch. Scale bar indicates 4 mm (A), 2 mm (B), 0.5 mm (C), 1.5 mm (D, E).

FIGURE 8. Palaemon colossus sp. nov. A. First pleopod male. B. First pleopod female. C. Telson. D. Marginal lanceolate setae of telson. A ♂ (pocl 6.0 mm), ZMAUTH – G 3 – 30, Epta Piges, Rhodes Island, Greece, 2002, coll. Anastasiadou Ch.; B – D holotype ♀ (pocl 8.5 mm), OUMNH. ZC. 2014 – 13 – 001, Epta Piges, Rhodes Island, Greece. Scale bar indicates 1 mm (A – C), 0.4 mm (D).

FIGURE 9. Palaemon minos sp. nov. A. Whole animal, lateral view. B. Fifth pleuron. C. Telson distal part. D. Thoracic sternal armature. E. Abdominal sternal armature. A – E holotype ♂ (pocl 4.5 mm), OUMNH. ZC. 2014 – 13 – 003, Kourna Lake, Crete, Greece; D – E ♀ (pocl 7.0 mm), ZMAUTH – G 3 – 31, Kourna Lake, Crete, Greece; Scale bar indicates 4 mm (A), 1.5 mm (B, D, E), 0.5 mm (C).

FIGURE 10. A. Fifth pleuron of P. zariquieyi. B. Maxillula of P. varians. C. Telson distal part of P. v a r i an s. D. Telson distal part of P. mesopotamicus. E. Telson distal part of P. zariquieyi. F. First maxilliped of P. varians. G. Third maxilliped of P. mesopotamicus. H. Scaphocerite of P. mesopotamicus. A, E, ♀ (pocl 7.0 mm), OUMNH. ZC. 2004 – 11 – 001, Las Turberas, Prat de Cabamas, Torreblanca, Spain; B – C, F, ♀ (pocl 7.2 mm), NHM 1959.10.17.72 – 82, Roose Cote, Power Station, Morecambe Bay, United Kingdom; D, G – H, ♀ (pocl 6.9 mm), SMF – TSH 30 / 88, Khabur river, Syria. Scale bar indicates 3 mm (A), 1 mm (B – E), 1.5 mm (F), 2 mm (G), 5 mm (H).