Ectinosomatidae. Body cylindrical, slightly compressed laterally, without definite demarcation between urosome and prosome. All somites except the penultimate somite with hyaline frills. Genital double somite without any trace of subdivision. Penultimate somite with a parabolic shaped pseudo-operculum. Anal somite ornamented with cuticular projections. Antennule 5 or 6 segmented in female, first segment with a long plumose seta; 6 or 7 segmented in male. Antenna basis distinct, with two segmented endopod and three segmented exopod, first segment of exopod naked or with a seta at inner distal corner, second segment with a seta at inner distal corner, last segment bears a short and a relatively long seta apically. Maxillae well developed, syncoxa slightly longer than wide, with three endites, basis elongated, about two times as long as syncoxa, slightly tapers to the tip, endopod uni-segmented, very short and curved on the anterior margin of the basis. Maxilliped stenopodial. P1-P4 with three segmented rami. Endopod longer than exopod. Setal formula of the swimming legs:

Holotype ♀ [BM(NH) 1999.1236]

Antenna (Fig. 3C) with a distinct basis. Exopod (Fig. 3D) three segmented; first segment slightly longer than wide, bears a short unipinnate seta at distal corner; second segment short and squarish, armed with a unipinnate seta distally; third segment longest, about four times as long as wide, armed with two unipinnate setae at tip. Endopod two-segmented, second segment slightly shorter than the first, bears two unipinnate setae on inner edge and six setae apically.

Differs from all other members of the genus by the unique shape of the anal somite dorsal ornamentation which is a strongly chitinised symmetric projection, resembling three strong spines with a common base on dorsal surface.

Kazanlı beach/Mersin (st16), 09.04.2007, 36°48.614’N - 34°45.434’E. Leg. Süphan Karaytuğ, Serdar Sak, Alp Alper, Serdar Sönmez.

Holotype ♀ (ZMADYU2015/01) and paratype ♂ (ZMADYU2015/02) dissected in 8 slides, 13 ♀♀ and 11♂♂ in ethanol (BUZM).

1. Sampling st1 (3♀♀, 1♂), st13 (2♀), st17 (9♀♀, 7♂♂), st23 (13♀♀, 4♂♂), st29 (11♀♀), st33 (11♀♀, 1♂), st34 (8♀♀, 4♂♂), st39 (3♀♀), st40 (15♀♀), st41 (3♀♀, 3♂♂), st42 (4♂♂), st44 (1♀), st45 (16♀♀, 4♂♂), st52 (4♀♀, 6♂♂), st65 (2♀♀, 3♂♂), st66 (11♀♀, 11♂♂), st68 (1♀), st74 (2♀♀, 1♂); 2. Sampling st1 (2♀♀), st2 (20♀♀, 4♂♂), st7 (2♂♂), st8 (14♀♀, 20♂♂), st11 (13♀♀, 4♂♂), st23 (12♀♀, 3♂♂), st29 (2♀♀), st31 (1♀), st32 (4♀♀), st35 (4♀♀), st40 (3♀♀), st45 (3♀♀, 1♂), st46 (5♀♀, 4♂♂), st47 (26♀♀, 2♂♂), st50 (2♀♀, 3♂♂), st57 (5♀♀), st59 (1♀), st61 (1♀), st62 (1♀), st65 (11♀♀, 3♂♂), st66 (1♀), st67 (4♀♀, 3♂♂), stY1 (14♀♀), stY12 (1♀), stY13 (8♀♀, 10♂♂); 3. Sampling st1 (5♂♂), st4 (1♀, 2♂♂), st8 (9♀♀, 3♂♂), st11 (8♀♀, 1♂), st16 (2♀♀, 1♂), st17 (11♀♀, 9 ♂♂), st23 (5♀♀, 1♂), st26 (2♀♀), st29 (15♀♀, 2♂♂), st34 (2♂♂), st35 (29♀♀, 1♂), st38 (1♀), st40 (46♀♀, 4♂♂), st42 (3♀♀), st43 (1♀), st45 (12 ♀), st47 (3♀♀, 1♂), st49 (1♀), st52 (36♀♀, 1♂), st57 (5♀♀, 3♂♂), st65 (14♀♀, 3♂♂), st66 (13♀♀, 6♂♂), stY1 (16♀♀, 10♂♂); 4. Sampling st23 (7♀♀), st26 (3♀♀) (BUZM).

Total body length from tip of rostrum to the posterior margin of the caudal rami 353 µm (267 - 412 µm, mean = 348 µm, n = 10). Body (Fig. 2A–C) cylindrical, urosome and prosome demarcation not distinct, slightly compressed laterally. All somites except the penultimate somite with hyaline frills as figured (Fig. 2A, B). Antenna, mouthparts and swimming legs partially covered with the lateral extensions of the urosomites. Penultimate somite with a parabolic shaped pseudo-operculum on posterior margin dorsally. Anal somite (Fig. 4A) armed with a strongly chitinised symmetric projection, resembling three strong spines with a common base on dorsal surface, bears a pair of pores and a pair of sensillae dorsally and a pair of tube pores on ventral surface. Surface cuticle of anal somite and caudal rami wrinkled (Figs 3B, 4A).

Caudal rami (Figs 3B, 4A, B) longer than wide, posterior margin prolonged as a hyaline membrane that covers the bases of seta IV and V, bears seven setae and a tube pore near the base of seta VII; seta I short and naked, seta II long and naked, seta III naked, longer than seta II, seta IV and V located at the terminal of the caudal rami, seta V about three times longer than seta IV, with a fracture plane basally (Fig. 2C), seta VI naked, located at the inner distal corner of the caudal rami, seta VII located at the dorsal surface, tri-articulated at base.

Rostrum (Figs 3A, 4C) distinct at base, spearhead shaped, cuticle of anterior surface wrinkled, bears two sensillae, curved to ventral at tip.

Antennule (Figs 3A, 4C) short, five segmented. First segment squarish, second segment is longer than wide, third segment slightly longer than wide, bears an aesthetasc which originates from the inner distal corner of the ventral surface, fourth segment short, slightly longer than wide, fifth segment long and narrow, about four times longer than wide, bears an apical acrothek consisting of a long aesthetasc fused basally to one very long and one short bare setae. Setal formula as follows: 1- [1 plumose], 2-[4+3 spinulose +1 plumose], 3- [3+(1+ae)], 4- [1], 5 [6+acrothek].

Antenna (Fig. 6E) with a short and naked coxa. Basis slightly longer than wide, clearly distinct from endopod. Exopod three segmented; first segment slightly longer than wide, bears a short unipinnate seta at distal corner; second segment short and squarish, armed with a unipinnate seta distally; third segment longest, about three times as long as wide, armed with a transverse row of spinules near apical margin, with two unipinnate setae at tip. Endopod two segmented, first segment about three times longer than wide, ornamented with a transverse row of spinules apically; second segment shorter than the first, about two times as long as wide ornamented with short spinules along apical margin, bears two short unipinnate setae on inner edge and six spinulose and one plumose setae apically.

Mandible (Fig. 5A, B). Gnathobase well developed, armed with 8 teeth that fused to cutting edge. Basis longer than wide, clearly narrower at base, bears one plumose and two bipinnate setae. Exopod reduced to a short and squarish segment, armed with one short bare and two relatively longer plumose setae. Endopod uni-segmented, rectangular, ornamented with fine spinules at outer margin, bears three long bare setae at inner margin, one short plumose seta at outer distal corner, one long plumose and four bare setae apically which of two fused at base (arrowed in Fig. 5B)

Maxillule (Fig. 5C, D). Pre-coxal arthrite with four setae. Coxa, basis and endopod fused, armed with five plumose setae which of two fused at base (arrowed in Fig. 5D) and eight bare setae. Exopod reduced to a very short segment, bears three minute bare setae.

Maxillae (Fig. 5E) Syncoxa slightly longer than wide, armed with two short seta near distal corner, bears a short cuticular projection near anterior margin, with three endites. First and second endite very short and narrow, located close to each other; first endite with one very short plumose and thick seta, second endite with one minute bare seta; third endite well developed, located near distal corner, bears one short and plumose seta at distal corner and two relatively long and plumose setae apically. Basis elongated, about two times as long as syncoxa, slightly tapers to the tip, armed with one plumose and two bare setae at inner margin. Endopod uni-segmented, very short, curved on the anterior margin of basis, bears seven setae which of two geniculate.

Maxilliped (Fig. 5F) stenopodial. Coxa squarish and naked. Basis elongated, about 4 times as long as basis and two times as long as endopod, bears a long plumose seta located at proximal corner, ornamented with fine spinules on both margins. Endopod long and narrow, armed with one plumose seta medially, bears one plumose and two bare setae apically.

P1-P4 (Fig. 6A–D) coxa well developed, armed with a row of tiny spinules on distal edge. Basis bears a bare seta at outer edge, with three segmented rami. Exopod shorter than endopod, first segment bears well developed spinules and a bare spiniform seta at outer edge, inner edge naked (P2-P4) or ornamented with fine spinules (P1); second segment with well-developed spinules and a bare spiniform seta at outer edge, bears a very long seta directed obliquely upwards, with a fringed tip; third segment ornamented with well-developed spinules, bears one bare and one unipinnate spiniform seta at outer edge, two setae apically, one (P1-P3) or two setae (P4, one of them directed obliquely upwards with a fringed tip) at inner margin. First endopod segment ornamented with a transverse row of spinules on anterior surface and distal margin, outer margin naked, bears a long bipinnate seta at inner margin; second segment ornamented with well-developed spinules along the outer and distal margins, bears a long plumose seta at inner margin and a hyaline seta located at the posterior surface (except P1); third segment with a short bare seta at outer distal corner, one short unipinnate and one relatively long unipinnate and plumose setae apically and a long plumose seta at inner margin. Setal formula of the swimming legs as follows:

P5 (Fig. 7A) baseo-endopod and exopod fused, baseo-endopod bears one long and plumose and one bare setae terminally. Exopod bears one relatively short and plumose and three very long and bare setae terminally and one short and bipinnate surface seta located near the proximal part of the exopodal lobe.

P6 (Fig. 7A) pairs fused and formed a short and broad plate, posterior margin of the plate ornamented with fine spinules, each side bears a very long, bare seta.

Antennule, P5 and P6 are sexually dimorphic. Total body length from tip of rostrum to the posterior margin of the caudal rami 364 µm (253-364 µm, mean = 322 µm, n = 6). Body ornamentation (Fig. 2D) generally as in female.

Antennule (Fig. 4D) seven segmented. First and second segment short and broad, third segment widest, fourth segment very short, located at the posterior of the fifth segment, bears an aesthetasc, fifth segment longest, sixth segment with a naked seta, seventh segment with an acrothek at tip, consisting of one short aesthetasc and two bare setae fused at base. Setal formula: 1-[0], 2-[1], 3-[7+1 plumose], 4-[2 + ae], 5-[7], 6-[1], 7-[6+acrothek].

P5 (Fig. 7B) baseo-endopod and exopod distinction clear. Baseo-endopod armed with two bare setae terminally. Exopod armed with one bare surface seta and three bare and one plumose terminal setae, bears two tube pores.

P6 (Fig. 7B) baseo-endopod and exopod fused forming a triangular plate, armed with two bare setae and two minute mucroniform projections. P6 bearing somite with a long bare seta at each side of the P6 originated from a button like structure.

The specific name “lanceorostrata” refers to the spearhead shaped rostrum.