Meximaera diffidentia Barnard

Krapp-Schickel, Traudl & Vader, Wim, 2009, On some Maerid genera (Crustacea, Amphipoda, Maeridae) collected by the Hourglass Cruises (Florida). Part 1: Genera Anamaera, Ceradocus, Clessidra gen. nov., Jerbarnia, Maera, Meximaera, with a key to world Ceradocus, Journal of Natural History 43 (33 - 34), pp. 2057-2086 : 2082-2085

Meximaera diffidentia Barnard

( Figure 10 )

Meximaera diffidentia Barnard, 1969: 209–211 , figs. 21, 22; Krapp-Schickel, 2008a: 1424–1427, fig. 1

Maera caroliniana Bynum and Fox, 1977: 11–14 ; LeCroy, 2000: 107, fig. 145.

Type locality

Gulf of California , Mexico .

Material examined (all collected with Shipek grab)

FSBC I 14592: HI-9; 1; 14–15 September 1971; 7.6 m; 27°37′ N, 80°13′24″ W . FSBC I 14593: HI-11; 1 male; 14–15 September 1971; 7.6 m; 27°21′42″ N, 80°13′24″ W . FSBC I 14594: HI-17; 1 adult; 15 IC 1971; 11.2 m; 27°21′13″ N, 80°13′24″ W . FSBC I 14595: HI-18; 15; slide; 15 September 1971; 11.2 m; 27°21′23″ N, 80°13′24″ W . FSBC I 14596: HI-19; 2 adults; 15 September 1971; 11.2 m; 27°21′23″ N, 80°13′24″ W . FSBC I 14597: HI-20; 3 adults; 15 September 1971; 11.2 m; 27°21′23″ N, 80°13′24″ W . FSBC I 14598: HI-21; 2 adults; 15 September 1971; 11.2 m; 27°21′23″ N, 80°13′24″ W . FSBC I 14599: HI-24; 6; 15 September 1971; 12.1 m; 27°20′24″ N, 80°13′04″ W . FSBC I 14600: HI-25; 1 adult; 15 September 1971; 12.1 m; 27°20′24″ N, 80°13′04″ W . FSBC I 14601: HI-26; 2 juveniles + 1 female ov.; 15 September 1971; 12.1 m; 27°20′24″ N, 80°13′04″ W . FSBC I 14602: HI-28; 1 adult; 15 September 1971; 12.1 m; 27°20′24″ N, 80°13′04″ W . FSBC I 14603: HI-31; 4 adults; 16 September 1971; 11.2 m; 27°22′08″ N, 80°13′46″ W . FSBC I 14604: HI-32; 15 juveniles and adults; 16 September 1971; 11.2 m; 27°22′08″ N, 80°13′46″ W . FSBC I 14606: HI-34; 6; 16 September 1971; 11.2 m; 27°22′08″ N, 80°13′46″ W . FSBC I 14607: HI-35; 7 adults; 16 September 1971; 11.2 m; 27°22′08″ N, 80°13′46″ W . FSBC I 14608: HI-61; 1 adult; 1 November 1971; 8.5 m; 27°21′06″ N, 80°13′58″ W . FSBC I 14609: HI-69; 2 adults; 3 November 1971; 11.2 m; 27°21′23″ N, 80°13′24″ W . FSBC I 14611: HI-94; 6, one ovigerous female; 14 November 1971; 10.9 m; 27°22′08″ N, 80°13′06″ W . FSBC I 14612: HI- 97; 1 juvenile; 14 November 1971; 10.3 m; 27°20′24″ N, 80°13′04″ W . FSBC I 14613: HI-231; 1 adult, 1 juvenile; 14 March 1972; 11.5 m; 27°21′23″ N, 80°13′24″ W . FSBC I 14615: HI-329; 1 adult; 5 July 1972; 11.5 m; 27°21′23″ N, 80°13′24″ W . FSBC I 14618: HI-406; 1; 7 September 1972; 27°21′23″ N, 80°13′24″ W . FSBC I 14619: HI-407; 2 adults; 7 September 1972; 11.2 m; 27°21′23″ N, 80°13′24″ W . FSBC I 14620: HI-408; 1 adult; 7 September 1972; 11.2 m; 27°21′23″ N, 80°13′24″ W . FSBC I 14621: HI-409; 3 adults; 7 September 1972; 11.2 m; 27°21′23″ N, 80°13′24″ W . FSBC I 14622: HI-424; 2 adults; 7 September 1972; 10.3 m; 27°20′24″ N, 80°13′04″ W . FSBC I 14623: HI-425; 2 adults; 7 September 1972; 10.3 m; 27°20′24″ N, 80°13′04″ W . FSBC I 14624: HI-426; 1; 7 September 1972; 10.3 m; 27°20′24″ N, 80°13′04″ W . FSBC I 14625: HI-427; 1?female, 1 adult; 7 November 1972; 10.5 m; 27°20′24″ N, 80°13′04″ W . FSBC I 14626: HI-434; 1 adult; 7 September 1972; 11.8 m; 27°22′08″ N, 80°13′46″ W . FSBC I 14628: HI-436; 1 adult; 7 September 1972; 11.8 m;. FSBC I 14629: HI-437; 3; 7 September 1972; 11.8 m; 27°22′08″ N, 80°13′46″ W . FSBC I 14631: HI-506; slide; 2 November 1972; 10.9 m; 27°21′23″ N, 80°13′24″ W . FSBC I 14632: HI-506; 2 incompl.; 3 November 1972; 10.6 m; 27°22′08″ N, 80°13′46″ W . FSBC I 14633: HI-547; 1; 4 January 1973; 10.9 m; 27°21′23″ N, 80°13′24″ W . FSBC I 14634: HI-572; 1; 5 January 1973; 10.3 m; 27°22′08″ N, 80°13′46″ W . FSBC I 14635: HI-573; 1 adult; 5 January 1973; 10.3 m; 27°22′08″ N, 80°13′46″ W . FSBC I 14636: HI-574; 3 adults; 5 January 1973; 10.3 m; 27°22′08″ N, 80°13′46″ W . FSBC I 14637: HI-633; 1 adult; 6 March 1973; 10.9 m; 27°20′24″ N, 80°13′04″ W . FSBC I 14638: HI-685; 1; 14 May 1973; 11.2 m; 27°21′23″ N, 80°13′24″ W . FSBC I 14639: HI-702; 1 adult; 15 May 1973; 10 m; 27°20′24″ N, 80°13′04″ W . FSBC I 14640: HI-703; 2; 15 May 1973; 10 m; 27°22′08″ N, 80°13′06″ W . FSBC I 14641: HI-710; 1 female with four eggs; 15 May 1973; 10.6 m; 27°22′08″ N, 80°13′46″ W . FSBC I 14642: HI-750; 1 adult; 8 July 1973; 7 m; 27°21′06″ N, 80°13′58″ W . FSBC I 14643: HI-757; 2 adults; 9 July 1973; 10 m; 27°21′23″ N, 80°13′24″ W . FSBC I 14644: HI-783; 3; 9 July 1973; 9.7 m; 27°22′08″ N, 80°13′46″ W . FSBC I 14646: HI-786; 1 adult; 9 July 1973; 9.7 m; 27°22′08″ N, 80°13′46″ W . FSBC I 14647: HI-787; 1 adult; 9 July 1973; 9.7 m; 27°22′08″ N, 80°13′46″ W .

Length

4–6 mm.

Redescription after slide FSBC I 14595 and habitus FSBC 14593.

Habitus. Body smooth. Head somewhat wider than first body segment. Lateral cephalic lobes truncate, no notch found.

Head. Eyes round. Antenna 1 longer than A2 and longer than half body length, peduncle longer than flagellum, peduncle art1 subequal or shorter than art2, but much thicker, peduncle art two to three times longer than art3; flagellum with 9–10 arts, flag. acc. with two arts. Antenna 2 gland cone not reaching end of peduncular art3; art4> art5, flagellum subequal or shorter peduncle art5, with five arts.

Mouthparts. Upper lip anteriorly thickened and lobate. Mandible palp art1 not acutely produced, but obliquely ending; art2: art3 = 14: 11, art2 marginally and art3 distally with many long setae. Maxilliped inner plate surpassing half length of outer plate, which can nearly reach end of palp art2 (carpus); art4 (dactylus) slender, with nail or claw. Maxillae: Mx1 inner plate ovoid, distally three long setae; Mx2 outer plate with somewhat triangular margin distally and both sides densely beset with long setae; inner plate with dense distal and some marginal setae, but oblique setal row lacking. Lower lip: inner lobes and processus mandibularis well developed.

Gnathopods. Coxa 1 anterodistal corner produced and regularly rounded. Gn1 not sexually dimorphic; propodus and carpus subequal in length, posteriorly regularly rounded, palmar corner scarcely visible. Gn 2 in both sexes symmetrical, propodus clearly longer than carpus, palmar margin somewhat concave, palmar corner poorly defined, propodus posterior margin irregularly beset with spine-shaped setae and groups of fine setae.

Peraeopods. P3, 4 similar in shape, P4 smaller. P5–7 bases widened, distally narrowing, distoposterior corner not widened to lobe; dactylus with nail.

Pleon. Dorsally smooth. Epimeral plates smooth, posteroventral corner with upturned tip.

Uropods. U1 inferior margin with subproximal spine-shaped seta, subequal rami <peduncle; U2 rami longer than peduncle. U3 rami three times length of peduncle, distally truncated, outer ramus with minute second article.

Telson . Somewhat longer than wide, on outer and distal margin with spine-shaped setae; lobes distally excavated, in excavation and on the outer margin with spineshaped seta. Only half cleft, about half the distance to base.

Female (sexually dimorphic characters). Gnathopods are generally somewhat wider and both Gn1 and Gn2 sometimes slightly asymmetrical with one side as in males, one wider (see Krapp-Schickel 2008a; fig. 2). Oostegites are very slender, which might indicate that the species lives in the interstitium.

Features for regional diagnosis

Cx1 with broadly rounded anteroventral angle is similar to that of C. shoemakeri , but the species treated here is totally smooth on Ep and Us.

Remarks

Despite the fact that Meximaera diffidentia Barnard is described from Bahia de Los Angeles, Gulf of California (Pacific Ocean), it shows absolutely no morphological difference to Maera caroliniana Bynum and Fox from North Carolina (Atlantic Ocean), and matches the present material from Florida perfectly.

It is interesting that Barnard (1969: 209) writes first about U3 “minutely biarticulate” in the description, but later stresses the “strongly biarticulate outer ramus of uropod 3”, which is here not the case: the second article is really very small. More noteworthy is the fact that the telson is not deeply cleft as in most Maeridae , but only halfway, a fact not mentioned at all in Barnard (1969), but illustrated and described for M. caroliniana Bynum and Fox 1977: 13 fig. 7.

Distribution

Hutchinson Island , St Lucie County, Gulf of California ( Barnard 1969) ; off east coast of Florida, North Atlantic Ocean ( Bynum and Fox 1977). Present material: W. Florida .

Ecology

Depth of 0.46–2.17 m ( Krapp-Schickel 2004), here down to 12.1 m; sand. As all specimens were collected with the Shipek grab, it could be surmised that this species lives on or even in the sand.

Figures

Figure 10. Meximaera diffidentia male 5.5 mm, FSBC I 14595. Mx1,2, maxilla 1,2; LL, lower lip; Mdp, mandible palp; Gn1,2, gnathopod 1,2; U3, uropod 3; U3′, enlarged tip of U3; T, telson.